// https://d3js.org v7.9.0 Copyright 2010-2021 Mike Bostock
var version = "7.9.0";

function define(constructor, factory, prototype) {
  constructor.prototype = factory.prototype = prototype;
  prototype.constructor = constructor;
}

function extend(parent, definition) {
  var prototype = Object.create(parent.prototype);
  for (var key in definition) prototype[key] = definition[key];
  return prototype;
}

function Color() {}

var darker = 0.7;
var brighter = 1 / darker;

var reI = "\\s*([+-]?\\d+)\\s*",
    reN = "\\s*([+-]?(?:\\d*\\.)?\\d+(?:[eE][+-]?\\d+)?)\\s*",
    reP = "\\s*([+-]?(?:\\d*\\.)?\\d+(?:[eE][+-]?\\d+)?)%\\s*",
    reHex = /^#([0-9a-f]{3,8})$/,
    reRgbInteger = new RegExp(`^rgb\\(${reI},${reI},${reI}\\)$`),
    reRgbPercent = new RegExp(`^rgb\\(${reP},${reP},${reP}\\)$`),
    reRgbaInteger = new RegExp(`^rgba\\(${reI},${reI},${reI},${reN}\\)$`),
    reRgbaPercent = new RegExp(`^rgba\\(${reP},${reP},${reP},${reN}\\)$`),
    reHslPercent = new RegExp(`^hsl\\(${reN},${reP},${reP}\\)$`),
    reHslaPercent = new RegExp(`^hsla\\(${reN},${reP},${reP},${reN}\\)$`);

var named = {
  aliceblue: 0xf0f8ff,
  antiquewhite: 0xfaebd7,
  aqua: 0x00ffff,
  aquamarine: 0x7fffd4,
  azure: 0xf0ffff,
  beige: 0xf5f5dc,
  bisque: 0xffe4c4,
  black: 0x000000,
  blanchedalmond: 0xffebcd,
  blue: 0x0000ff,
  blueviolet: 0x8a2be2,
  brown: 0xa52a2a,
  burlywood: 0xdeb887,
  cadetblue: 0x5f9ea0,
  chartreuse: 0x7fff00,
  chocolate: 0xd2691e,
  coral: 0xff7f50,
  cornflowerblue: 0x6495ed,
  cornsilk: 0xfff8dc,
  crimson: 0xdc143c,
  cyan: 0x00ffff,
  darkblue: 0x00008b,
  darkcyan: 0x008b8b,
  darkgoldenrod: 0xb8860b,
  darkgray: 0xa9a9a9,
  darkgreen: 0x006400,
  darkgrey: 0xa9a9a9,
  darkkhaki: 0xbdb76b,
  darkmagenta: 0x8b008b,
  darkolivegreen: 0x556b2f,
  darkorange: 0xff8c00,
  darkorchid: 0x9932cc,
  darkred: 0x8b0000,
  darksalmon: 0xe9967a,
  darkseagreen: 0x8fbc8f,
  darkslateblue: 0x483d8b,
  darkslategray: 0x2f4f4f,
  darkslategrey: 0x2f4f4f,
  darkturquoise: 0x00ced1,
  darkviolet: 0x9400d3,
  deeppink: 0xff1493,
  deepskyblue: 0x00bfff,
  dimgray: 0x696969,
  dimgrey: 0x696969,
  dodgerblue: 0x1e90ff,
  firebrick: 0xb22222,
  floralwhite: 0xfffaf0,
  forestgreen: 0x228b22,
  fuchsia: 0xff00ff,
  gainsboro: 0xdcdcdc,
  ghostwhite: 0xf8f8ff,
  gold: 0xffd700,
  goldenrod: 0xdaa520,
  gray: 0x808080,
  green: 0x008000,
  greenyellow: 0xadff2f,
  grey: 0x808080,
  honeydew: 0xf0fff0,
  hotpink: 0xff69b4,
  indianred: 0xcd5c5c,
  indigo: 0x4b0082,
  ivory: 0xfffff0,
  khaki: 0xf0e68c,
  lavender: 0xe6e6fa,
  lavenderblush: 0xfff0f5,
  lawngreen: 0x7cfc00,
  lemonchiffon: 0xfffacd,
  lightblue: 0xadd8e6,
  lightcoral: 0xf08080,
  lightcyan: 0xe0ffff,
  lightgoldenrodyellow: 0xfafad2,
  lightgray: 0xd3d3d3,
  lightgreen: 0x90ee90,
  lightgrey: 0xd3d3d3,
  lightpink: 0xffb6c1,
  lightsalmon: 0xffa07a,
  lightseagreen: 0x20b2aa,
  lightskyblue: 0x87cefa,
  lightslategray: 0x778899,
  lightslategrey: 0x778899,
  lightsteelblue: 0xb0c4de,
  lightyellow: 0xffffe0,
  lime: 0x00ff00,
  limegreen: 0x32cd32,
  linen: 0xfaf0e6,
  magenta: 0xff00ff,
  maroon: 0x800000,
  mediumaquamarine: 0x66cdaa,
  mediumblue: 0x0000cd,
  mediumorchid: 0xba55d3,
  mediumpurple: 0x9370db,
  mediumseagreen: 0x3cb371,
  mediumslateblue: 0x7b68ee,
  mediumspringgreen: 0x00fa9a,
  mediumturquoise: 0x48d1cc,
  mediumvioletred: 0xc71585,
  midnightblue: 0x191970,
  mintcream: 0xf5fffa,
  mistyrose: 0xffe4e1,
  moccasin: 0xffe4b5,
  navajowhite: 0xffdead,
  navy: 0x000080,
  oldlace: 0xfdf5e6,
  olive: 0x808000,
  olivedrab: 0x6b8e23,
  orange: 0xffa500,
  orangered: 0xff4500,
  orchid: 0xda70d6,
  palegoldenrod: 0xeee8aa,
  palegreen: 0x98fb98,
  paleturquoise: 0xafeeee,
  palevioletred: 0xdb7093,
  papayawhip: 0xffefd5,
  peachpuff: 0xffdab9,
  peru: 0xcd853f,
  pink: 0xffc0cb,
  plum: 0xdda0dd,
  powderblue: 0xb0e0e6,
  purple: 0x800080,
  rebeccapurple: 0x663399,
  red: 0xff0000,
  rosybrown: 0xbc8f8f,
  royalblue: 0x4169e1,
  saddlebrown: 0x8b4513,
  salmon: 0xfa8072,
  sandybrown: 0xf4a460,
  seagreen: 0x2e8b57,
  seashell: 0xfff5ee,
  sienna: 0xa0522d,
  silver: 0xc0c0c0,
  skyblue: 0x87ceeb,
  slateblue: 0x6a5acd,
  slategray: 0x708090,
  slategrey: 0x708090,
  snow: 0xfffafa,
  springgreen: 0x00ff7f,
  steelblue: 0x4682b4,
  tan: 0xd2b48c,
  teal: 0x008080,
  thistle: 0xd8bfd8,
  tomato: 0xff6347,
  turquoise: 0x40e0d0,
  violet: 0xee82ee,
  wheat: 0xf5deb3,
  white: 0xffffff,
  whitesmoke: 0xf5f5f5,
  yellow: 0xffff00,
  yellowgreen: 0x9acd32
};

define(Color, color, {
  copy(channels) {
    return Object.assign(new this.constructor, this, channels);
  },
  displayable() {
    return this.rgb().displayable();
  },
  hex: color_formatHex, // Deprecated! Use color.formatHex.
  formatHex: color_formatHex,
  formatHex8: color_formatHex8,
  formatHsl: color_formatHsl,
  formatRgb: color_formatRgb,
  toString: color_formatRgb
});

function color_formatHex() {
  return this.rgb().formatHex();
}

function color_formatHex8() {
  return this.rgb().formatHex8();
}

function color_formatHsl() {
  return hslConvert(this).formatHsl();
}

function color_formatRgb() {
  return this.rgb().formatRgb();
}

function color(format) {
  var m, l;
  format = (format + "").trim().toLowerCase();
  return (m = reHex.exec(format)) ? (l = m[1].length, m = parseInt(m[1], 16), l === 6 ? rgbn(m) // #ff0000
      : l === 3 ? new Rgb((m >> 8 & 0xf) | (m >> 4 & 0xf0), (m >> 4 & 0xf) | (m & 0xf0), ((m & 0xf) << 4) | (m & 0xf), 1) // #f00
      : l === 8 ? rgba(m >> 24 & 0xff, m >> 16 & 0xff, m >> 8 & 0xff, (m & 0xff) / 0xff) // #ff000000
      : l === 4 ? rgba((m >> 12 & 0xf) | (m >> 8 & 0xf0), (m >> 8 & 0xf) | (m >> 4 & 0xf0), (m >> 4 & 0xf) | (m & 0xf0), (((m & 0xf) << 4) | (m & 0xf)) / 0xff) // #f000
      : null) // invalid hex
      : (m = reRgbInteger.exec(format)) ? new Rgb(m[1], m[2], m[3], 1) // rgb(255, 0, 0)
      : (m = reRgbPercent.exec(format)) ? new Rgb(m[1] * 255 / 100, m[2] * 255 / 100, m[3] * 255 / 100, 1) // rgb(100%, 0%, 0%)
      : (m = reRgbaInteger.exec(format)) ? rgba(m[1], m[2], m[3], m[4]) // rgba(255, 0, 0, 1)
      : (m = reRgbaPercent.exec(format)) ? rgba(m[1] * 255 / 100, m[2] * 255 / 100, m[3] * 255 / 100, m[4]) // rgb(100%, 0%, 0%, 1)
      : (m = reHslPercent.exec(format)) ? hsla(m[1], m[2] / 100, m[3] / 100, 1) // hsl(120, 50%, 50%)
      : (m = reHslaPercent.exec(format)) ? hsla(m[1], m[2] / 100, m[3] / 100, m[4]) // hsla(120, 50%, 50%, 1)
      : named.hasOwnProperty(format) ? rgbn(named[format]) // eslint-disable-line no-prototype-builtins
      : format === "transparent" ? new Rgb(NaN, NaN, NaN, 0)
      : null;
}

function rgbn(n) {
  return new Rgb(n >> 16 & 0xff, n >> 8 & 0xff, n & 0xff, 1);
}

function rgba(r, g, b, a) {
  if (a <= 0) r = g = b = NaN;
  return new Rgb(r, g, b, a);
}

function rgbConvert(o) {
  if (!(o instanceof Color)) o = color(o);
  if (!o) return new Rgb;
  o = o.rgb();
  return new Rgb(o.r, o.g, o.b, o.opacity);
}

function rgb(r, g, b, opacity) {
  return arguments.length === 1 ? rgbConvert(r) : new Rgb(r, g, b, opacity == null ? 1 : opacity);
}

function Rgb(r, g, b, opacity) {
  this.r = +r;
  this.g = +g;
  this.b = +b;
  this.opacity = +opacity;
}

define(Rgb, rgb, extend(Color, {
  brighter(k) {
    k = k == null ? brighter : Math.pow(brighter, k);
    return new Rgb(this.r * k, this.g * k, this.b * k, this.opacity);
  },
  darker(k) {
    k = k == null ? darker : Math.pow(darker, k);
    return new Rgb(this.r * k, this.g * k, this.b * k, this.opacity);
  },
  rgb() {
    return this;
  },
  clamp() {
    return new Rgb(clampi(this.r), clampi(this.g), clampi(this.b), clampa(this.opacity));
  },
  displayable() {
    return (-0.5 <= this.r && this.r < 255.5)
        && (-0.5 <= this.g && this.g < 255.5)
        && (-0.5 <= this.b && this.b < 255.5)
        && (0 <= this.opacity && this.opacity <= 1);
  },
  hex: rgb_formatHex, // Deprecated! Use color.formatHex.
  formatHex: rgb_formatHex,
  formatHex8: rgb_formatHex8,
  formatRgb: rgb_formatRgb,
  toString: rgb_formatRgb
}));

function rgb_formatHex() {
  return `#${hex(this.r)}${hex(this.g)}${hex(this.b)}`;
}

function rgb_formatHex8() {
  return `#${hex(this.r)}${hex(this.g)}${hex(this.b)}${hex((isNaN(this.opacity) ? 1 : this.opacity) * 255)}`;
}

function rgb_formatRgb() {
  const a = clampa(this.opacity);
  return `${a === 1 ? "rgb(" : "rgba("}${clampi(this.r)}, ${clampi(this.g)}, ${clampi(this.b)}${a === 1 ? ")" : `, ${a})`}`;
}

function clampa(opacity) {
  return isNaN(opacity) ? 1 : Math.max(0, Math.min(1, opacity));
}

function clampi(value) {
  return Math.max(0, Math.min(255, Math.round(value) || 0));
}

function hex(value) {
  value = clampi(value);
  return (value < 16 ? "0" : "") + value.toString(16);
}

function hsla(h, s, l, a) {
  if (a <= 0) h = s = l = NaN;
  else if (l <= 0 || l >= 1) h = s = NaN;
  else if (s <= 0) h = NaN;
  return new Hsl(h, s, l, a);
}

function hslConvert(o) {
  if (o instanceof Hsl) return new Hsl(o.h, o.s, o.l, o.opacity);
  if (!(o instanceof Color)) o = color(o);
  if (!o) return new Hsl;
  if (o instanceof Hsl) return o;
  o = o.rgb();
  var r = o.r / 255,
      g = o.g / 255,
      b = o.b / 255,
      min = Math.min(r, g, b),
      max = Math.max(r, g, b),
      h = NaN,
      s = max - min,
      l = (max + min) / 2;
  if (s) {
    if (r === max) h = (g - b) / s + (g < b) * 6;
    else if (g === max) h = (b - r) / s + 2;
    else h = (r - g) / s + 4;
    s /= l < 0.5 ? max + min : 2 - max - min;
    h *= 60;
  } else {
    s = l > 0 && l < 1 ? 0 : h;
  }
  return new Hsl(h, s, l, o.opacity);
}

function hsl(h, s, l, opacity) {
  return arguments.length === 1 ? hslConvert(h) : new Hsl(h, s, l, opacity == null ? 1 : opacity);
}

function Hsl(h, s, l, opacity) {
  this.h = +h;
  this.s = +s;
  this.l = +l;
  this.opacity = +opacity;
}

define(Hsl, hsl, extend(Color, {
  brighter(k) {
    k = k == null ? brighter : Math.pow(brighter, k);
    return new Hsl(this.h, this.s, this.l * k, this.opacity);
  },
  darker(k) {
    k = k == null ? darker : Math.pow(darker, k);
    return new Hsl(this.h, this.s, this.l * k, this.opacity);
  },
  rgb() {
    var h = this.h % 360 + (this.h < 0) * 360,
        s = isNaN(h) || isNaN(this.s) ? 0 : this.s,
        l = this.l,
        m2 = l + (l < 0.5 ? l : 1 - l) * s,
        m1 = 2 * l - m2;
    return new Rgb(
      hsl2rgb(h >= 240 ? h - 240 : h + 120, m1, m2),
      hsl2rgb(h, m1, m2),
      hsl2rgb(h < 120 ? h + 240 : h - 120, m1, m2),
      this.opacity
    );
  },
  clamp() {
    return new Hsl(clamph(this.h), clampt(this.s), clampt(this.l), clampa(this.opacity));
  },
  displayable() {
    return (0 <= this.s && this.s <= 1 || isNaN(this.s))
        && (0 <= this.l && this.l <= 1)
        && (0 <= this.opacity && this.opacity <= 1);
  },
  formatHsl() {
    const a = clampa(this.opacity);
    return `${a === 1 ? "hsl(" : "hsla("}${clamph(this.h)}, ${clampt(this.s) * 100}%, ${clampt(this.l) * 100}%${a === 1 ? ")" : `, ${a})`}`;
  }
}));

function clamph(value) {
  value = (value || 0) % 360;
  return value < 0 ? value + 360 : value;
}

function clampt(value) {
  return Math.max(0, Math.min(1, value || 0));
}

/* From FvD 13.37, CSS Color Module Level 3 */
function hsl2rgb(h, m1, m2) {
  return (h < 60 ? m1 + (m2 - m1) * h / 60
      : h < 180 ? m2
      : h < 240 ? m1 + (m2 - m1) * (240 - h) / 60
      : m1) * 255;
}

const radians = Math.PI / 180;
const degrees$1 = 180 / Math.PI;

// https://observablehq.com/@mbostock/lab-and-rgb
const K = 18,
    Xn = 0.96422,
    Yn = 1,
    Zn = 0.82521,
    t0$1 = 4 / 29,
    t1$1 = 6 / 29,
    t2 = 3 * t1$1 * t1$1,
    t3 = t1$1 * t1$1 * t1$1;

function labConvert(o) {
  if (o instanceof Lab) return new Lab(o.l, o.a, o.b, o.opacity);
  if (o instanceof Hcl) return hcl2lab(o);
  if (!(o instanceof Rgb)) o = rgbConvert(o);
  var r = rgb2lrgb(o.r),
      g = rgb2lrgb(o.g),
      b = rgb2lrgb(o.b),
      y = xyz2lab((0.2225045 * r + 0.7168786 * g + 0.0606169 * b) / Yn), x, z;
  if (r === g && g === b) x = z = y; else {
    x = xyz2lab((0.4360747 * r + 0.3850649 * g + 0.1430804 * b) / Xn);
    z = xyz2lab((0.0139322 * r + 0.0971045 * g + 0.7141733 * b) / Zn);
  }
  return new Lab(116 * y - 16, 500 * (x - y), 200 * (y - z), o.opacity);
}

function gray(l, opacity) {
  return new Lab(l, 0, 0, opacity == null ? 1 : opacity);
}

function lab(l, a, b, opacity) {
  return arguments.length === 1 ? labConvert(l) : new Lab(l, a, b, opacity == null ? 1 : opacity);
}

function Lab(l, a, b, opacity) {
  this.l = +l;
  this.a = +a;
  this.b = +b;
  this.opacity = +opacity;
}

define(Lab, lab, extend(Color, {
  brighter(k) {
    return new Lab(this.l + K * (k == null ? 1 : k), this.a, this.b, this.opacity);
  },
  darker(k) {
    return new Lab(this.l - K * (k == null ? 1 : k), this.a, this.b, this.opacity);
  },
  rgb() {
    var y = (this.l + 16) / 116,
        x = isNaN(this.a) ? y : y + this.a / 500,
        z = isNaN(this.b) ? y : y - this.b / 200;
    x = Xn * lab2xyz(x);
    y = Yn * lab2xyz(y);
    z = Zn * lab2xyz(z);
    return new Rgb(
      lrgb2rgb( 3.1338561 * x - 1.6168667 * y - 0.4906146 * z),
      lrgb2rgb(-0.9787684 * x + 1.9161415 * y + 0.0334540 * z),
      lrgb2rgb( 0.0719453 * x - 0.2289914 * y + 1.4052427 * z),
      this.opacity
    );
  }
}));

function xyz2lab(t) {
  return t > t3 ? Math.pow(t, 1 / 3) : t / t2 + t0$1;
}

function lab2xyz(t) {
  return t > t1$1 ? t * t * t : t2 * (t - t0$1);
}

function lrgb2rgb(x) {
  return 255 * (x <= 0.0031308 ? 12.92 * x : 1.055 * Math.pow(x, 1 / 2.4) - 0.055);
}

function rgb2lrgb(x) {
  return (x /= 255) <= 0.04045 ? x / 12.92 : Math.pow((x + 0.055) / 1.055, 2.4);
}

function hclConvert(o) {
  if (o instanceof Hcl) return new Hcl(o.h, o.c, o.l, o.opacity);
  if (!(o instanceof Lab)) o = labConvert(o);
  if (o.a === 0 && o.b === 0) return new Hcl(NaN, 0 < o.l && o.l < 100 ? 0 : NaN, o.l, o.opacity);
  var h = Math.atan2(o.b, o.a) * degrees$1;
  return new Hcl(h < 0 ? h + 360 : h, Math.sqrt(o.a * o.a + o.b * o.b), o.l, o.opacity);
}

function lch(l, c, h, opacity) {
  return arguments.length === 1 ? hclConvert(l) : new Hcl(h, c, l, opacity == null ? 1 : opacity);
}

function hcl(h, c, l, opacity) {
  return arguments.length === 1 ? hclConvert(h) : new Hcl(h, c, l, opacity == null ? 1 : opacity);
}

function Hcl(h, c, l, opacity) {
  this.h = +h;
  this.c = +c;
  this.l = +l;
  this.opacity = +opacity;
}

function hcl2lab(o) {
  if (isNaN(o.h)) return new Lab(o.l, 0, 0, o.opacity);
  var h = o.h * radians;
  return new Lab(o.l, Math.cos(h) * o.c, Math.sin(h) * o.c, o.opacity);
}

define(Hcl, hcl, extend(Color, {
  brighter(k) {
    return new Hcl(this.h, this.c, this.l + K * (k == null ? 1 : k), this.opacity);
  },
  darker(k) {
    return new Hcl(this.h, this.c, this.l - K * (k == null ? 1 : k), this.opacity);
  },
  rgb() {
    return hcl2lab(this).rgb();
  }
}));

var A = -0.14861,
    B = 1.78277,
    C = -0.29227,
    D = -0.90649,
    E = 1.97294,
    ED = E * D,
    EB = E * B,
    BC_DA = B * C - D * A;

function cubehelixConvert(o) {
  if (o instanceof Cubehelix) return new Cubehelix(o.h, o.s, o.l, o.opacity);
  if (!(o instanceof Rgb)) o = rgbConvert(o);
  var r = o.r / 255,
      g = o.g / 255,
      b = o.b / 255,
      l = (BC_DA * b + ED * r - EB * g) / (BC_DA + ED - EB),
      bl = b - l,
      k = (E * (g - l) - C * bl) / D,
      s = Math.sqrt(k * k + bl * bl) / (E * l * (1 - l)), // NaN if l=0 or l=1
      h = s ? Math.atan2(k, bl) * degrees$1 - 120 : NaN;
  return new Cubehelix(h < 0 ? h + 360 : h, s, l, o.opacity);
}

function cubehelix(h, s, l, opacity) {
  return arguments.length === 1 ? cubehelixConvert(h) : new Cubehelix(h, s, l, opacity == null ? 1 : opacity);
}

function Cubehelix(h, s, l, opacity) {
  this.h = +h;
  this.s = +s;
  this.l = +l;
  this.opacity = +opacity;
}

define(Cubehelix, cubehelix, extend(Color, {
  brighter(k) {
    k = k == null ? brighter : Math.pow(brighter, k);
    return new Cubehelix(this.h, this.s, this.l * k, this.opacity);
  },
  darker(k) {
    k = k == null ? darker : Math.pow(darker, k);
    return new Cubehelix(this.h, this.s, this.l * k, this.opacity);
  },
  rgb() {
    var h = isNaN(this.h) ? 0 : (this.h + 120) * radians,
        l = +this.l,
        a = isNaN(this.s) ? 0 : this.s * l * (1 - l),
        cosh = Math.cos(h),
        sinh = Math.sin(h);
    return new Rgb(
      255 * (l + a * (A * cosh + B * sinh)),
      255 * (l + a * (C * cosh + D * sinh)),
      255 * (l + a * (E * cosh)),
      this.opacity
    );
  }
}));

var abs$1 = Math.abs;
var cos$1 = Math.cos;
var sin$1 = Math.sin;
var pi$2 = Math.PI;
var halfPi$1 = pi$2 / 2;
var tau$2 = pi$2 * 2;
var max$2 = Math.max;
var epsilon$2 = 1e-12;

function range$1(i, j) {
  return Array.from({length: j - i}, (_, k) => i + k);
}

function compareValue(compare) {
  return function(a, b) {
    return compare(
      a.source.value + a.target.value,
      b.source.value + b.target.value
    );
  };
}

function chord() {
  return chord$1(false, false);
}

function chordTranspose() {
  return chord$1(false, true);
}

function chordDirected() {
  return chord$1(true, false);
}

function chord$1(directed, transpose) {
  var padAngle = 0,
      sortGroups = null,
      sortSubgroups = null,
      sortChords = null;

  function chord(matrix) {
    var n = matrix.length,
        groupSums = new Array(n),
        groupIndex = range$1(0, n),
        chords = new Array(n * n),
        groups = new Array(n),
        k = 0, dx;

    matrix = Float64Array.from({length: n * n}, transpose
        ? (_, i) => matrix[i % n][i / n | 0]
        : (_, i) => matrix[i / n | 0][i % n]);

    // Compute the scaling factor from value to angle in [0, 2pi].
    for (let i = 0; i < n; ++i) {
      let x = 0;
      for (let j = 0; j < n; ++j) x += matrix[i * n + j] + directed * matrix[j * n + i];
      k += groupSums[i] = x;
    }
    k = max$2(0, tau$2 - padAngle * n) / k;
    dx = k ? padAngle : tau$2 / n;

    // Compute the angles for each group and constituent chord.
    {
      let x = 0;
      if (sortGroups) groupIndex.sort((a, b) => sortGroups(groupSums[a], groupSums[b]));
      for (const i of groupIndex) {
        const x0 = x;
        if (directed) {
          const subgroupIndex = range$1(~n + 1, n).filter(j => j < 0 ? matrix[~j * n + i] : matrix[i * n + j]);
          if (sortSubgroups) subgroupIndex.sort((a, b) => sortSubgroups(a < 0 ? -matrix[~a * n + i] : matrix[i * n + a], b < 0 ? -matrix[~b * n + i] : matrix[i * n + b]));
          for (const j of subgroupIndex) {
            if (j < 0) {
              const chord = chords[~j * n + i] || (chords[~j * n + i] = {source: null, target: null});
              chord.target = {index: i, startAngle: x, endAngle: x += matrix[~j * n + i] * k, value: matrix[~j * n + i]};
            } else {
              const chord = chords[i * n + j] || (chords[i * n + j] = {source: null, target: null});
              chord.source = {index: i, startAngle: x, endAngle: x += matrix[i * n + j] * k, value: matrix[i * n + j]};
            }
          }
          groups[i] = {index: i, startAngle: x0, endAngle: x, value: groupSums[i]};
        } else {
          const subgroupIndex = range$1(0, n).filter(j => matrix[i * n + j] || matrix[j * n + i]);
          if (sortSubgroups) subgroupIndex.sort((a, b) => sortSubgroups(matrix[i * n + a], matrix[i * n + b]));
          for (const j of subgroupIndex) {
            let chord;
            if (i < j) {
              chord = chords[i * n + j] || (chords[i * n + j] = {source: null, target: null});
              chord.source = {index: i, startAngle: x, endAngle: x += matrix[i * n + j] * k, value: matrix[i * n + j]};
            } else {
              chord = chords[j * n + i] || (chords[j * n + i] = {source: null, target: null});
              chord.target = {index: i, startAngle: x, endAngle: x += matrix[i * n + j] * k, value: matrix[i * n + j]};
              if (i === j) chord.source = chord.target;
            }
            if (chord.source && chord.target && chord.source.value < chord.target.value) {
              const source = chord.source;
              chord.source = chord.target;
              chord.target = source;
            }
          }
          groups[i] = {index: i, startAngle: x0, endAngle: x, value: groupSums[i]};
        }
        x += dx;
      }
    }

    // Remove empty chords.
    chords = Object.values(chords);
    chords.groups = groups;
    return sortChords ? chords.sort(sortChords) : chords;
  }

  chord.padAngle = function(_) {
    return arguments.length ? (padAngle = max$2(0, _), chord) : padAngle;
  };

  chord.sortGroups = function(_) {
    return arguments.length ? (sortGroups = _, chord) : sortGroups;
  };

  chord.sortSubgroups = function(_) {
    return arguments.length ? (sortSubgroups = _, chord) : sortSubgroups;
  };

  chord.sortChords = function(_) {
    return arguments.length ? (_ == null ? sortChords = null : (sortChords = compareValue(_))._ = _, chord) : sortChords && sortChords._;
  };

  return chord;
}

const pi$1 = Math.PI,
    tau$1 = 2 * pi$1,
    epsilon$1 = 1e-6,
    tauEpsilon = tau$1 - epsilon$1;

function append(strings) {
  this._ += strings[0];
  for (let i = 1, n = strings.length; i < n; ++i) {
    this._ += arguments[i] + strings[i];
  }
}

function appendRound(digits) {
  let d = Math.floor(digits);
  if (!(d >= 0)) throw new Error(`invalid digits: ${digits}`);
  if (d > 15) return append;
  const k = 10 ** d;
  return function(strings) {
    this._ += strings[0];
    for (let i = 1, n = strings.length; i < n; ++i) {
      this._ += Math.round(arguments[i] * k) / k + strings[i];
    }
  };
}

class Path {
  constructor(digits) {
    this._x0 = this._y0 = // start of current subpath
    this._x1 = this._y1 = null; // end of current subpath
    this._ = "";
    this._append = digits == null ? append : appendRound(digits);
  }
  moveTo(x, y) {
    this._append`M${this._x0 = this._x1 = +x},${this._y0 = this._y1 = +y}`;
  }
  closePath() {
    if (this._x1 !== null) {
      this._x1 = this._x0, this._y1 = this._y0;
      this._append`Z`;
    }
  }
  lineTo(x, y) {
    this._append`L${this._x1 = +x},${this._y1 = +y}`;
  }
  quadraticCurveTo(x1, y1, x, y) {
    this._append`Q${+x1},${+y1},${this._x1 = +x},${this._y1 = +y}`;
  }
  bezierCurveTo(x1, y1, x2, y2, x, y) {
    this._append`C${+x1},${+y1},${+x2},${+y2},${this._x1 = +x},${this._y1 = +y}`;
  }
  arcTo(x1, y1, x2, y2, r) {
    x1 = +x1, y1 = +y1, x2 = +x2, y2 = +y2, r = +r;

    // Is the radius negative? Error.
    if (r < 0) throw new Error(`negative radius: ${r}`);

    let x0 = this._x1,
        y0 = this._y1,
        x21 = x2 - x1,
        y21 = y2 - y1,
        x01 = x0 - x1,
        y01 = y0 - y1,
        l01_2 = x01 * x01 + y01 * y01;

    // Is this path empty? Move to (x1,y1).
    if (this._x1 === null) {
      this._append`M${this._x1 = x1},${this._y1 = y1}`;
    }

    // Or, is (x1,y1) coincident with (x0,y0)? Do nothing.
    else if (!(l01_2 > epsilon$1));

    // Or, are (x0,y0), (x1,y1) and (x2,y2) collinear?
    // Equivalently, is (x1,y1) coincident with (x2,y2)?
    // Or, is the radius zero? Line to (x1,y1).
    else if (!(Math.abs(y01 * x21 - y21 * x01) > epsilon$1) || !r) {
      this._append`L${this._x1 = x1},${this._y1 = y1}`;
    }

    // Otherwise, draw an arc!
    else {
      let x20 = x2 - x0,
          y20 = y2 - y0,
          l21_2 = x21 * x21 + y21 * y21,
          l20_2 = x20 * x20 + y20 * y20,
          l21 = Math.sqrt(l21_2),
          l01 = Math.sqrt(l01_2),
          l = r * Math.tan((pi$1 - Math.acos((l21_2 + l01_2 - l20_2) / (2 * l21 * l01))) / 2),
          t01 = l / l01,
          t21 = l / l21;

      // If the start tangent is not coincident with (x0,y0), line to.
      if (Math.abs(t01 - 1) > epsilon$1) {
        this._append`L${x1 + t01 * x01},${y1 + t01 * y01}`;
      }

      this._append`A${r},${r},0,0,${+(y01 * x20 > x01 * y20)},${this._x1 = x1 + t21 * x21},${this._y1 = y1 + t21 * y21}`;
    }
  }
  arc(x, y, r, a0, a1, ccw) {
    x = +x, y = +y, r = +r, ccw = !!ccw;

    // Is the radius negative? Error.
    if (r < 0) throw new Error(`negative radius: ${r}`);

    let dx = r * Math.cos(a0),
        dy = r * Math.sin(a0),
        x0 = x + dx,
        y0 = y + dy,
        cw = 1 ^ ccw,
        da = ccw ? a0 - a1 : a1 - a0;

    // Is this path empty? Move to (x0,y0).
    if (this._x1 === null) {
      this._append`M${x0},${y0}`;
    }

    // Or, is (x0,y0) not coincident with the previous point? Line to (x0,y0).
    else if (Math.abs(this._x1 - x0) > epsilon$1 || Math.abs(this._y1 - y0) > epsilon$1) {
      this._append`L${x0},${y0}`;
    }

    // Is this arc empty? We’re done.
    if (!r) return;

    // Does the angle go the wrong way? Flip the direction.
    if (da < 0) da = da % tau$1 + tau$1;

    // Is this a complete circle? Draw two arcs to complete the circle.
    if (da > tauEpsilon) {
      this._append`A${r},${r},0,1,${cw},${x - dx},${y - dy}A${r},${r},0,1,${cw},${this._x1 = x0},${this._y1 = y0}`;
    }

    // Is this arc non-empty? Draw an arc!
    else if (da > epsilon$1) {
      this._append`A${r},${r},0,${+(da >= pi$1)},${cw},${this._x1 = x + r * Math.cos(a1)},${this._y1 = y + r * Math.sin(a1)}`;
    }
  }
  rect(x, y, w, h) {
    this._append`M${this._x0 = this._x1 = +x},${this._y0 = this._y1 = +y}h${w = +w}v${+h}h${-w}Z`;
  }
  toString() {
    return this._;
  }
}

function path() {
  return new Path;
}

// Allow instanceof d3.path
path.prototype = Path.prototype;

var slice = Array.prototype.slice;

function constant$4(x) {
  return function() {
    return x;
  };
}

function defaultSource(d) {
  return d.source;
}

function defaultTarget(d) {
  return d.target;
}

function defaultRadius(d) {
  return d.radius;
}

function defaultStartAngle(d) {
  return d.startAngle;
}

function defaultEndAngle(d) {
  return d.endAngle;
}

function defaultPadAngle() {
  return 0;
}

function defaultArrowheadRadius() {
  return 10;
}

function ribbon(headRadius) {
  var source = defaultSource,
      target = defaultTarget,
      sourceRadius = defaultRadius,
      targetRadius = defaultRadius,
      startAngle = defaultStartAngle,
      endAngle = defaultEndAngle,
      padAngle = defaultPadAngle,
      context = null;

  function ribbon() {
    var buffer,
        s = source.apply(this, arguments),
        t = target.apply(this, arguments),
        ap = padAngle.apply(this, arguments) / 2,
        argv = slice.call(arguments),
        sr = +sourceRadius.apply(this, (argv[0] = s, argv)),
        sa0 = startAngle.apply(this, argv) - halfPi$1,
        sa1 = endAngle.apply(this, argv) - halfPi$1,
        tr = +targetRadius.apply(this, (argv[0] = t, argv)),
        ta0 = startAngle.apply(this, argv) - halfPi$1,
        ta1 = endAngle.apply(this, argv) - halfPi$1;

    if (!context) context = buffer = path();

    if (ap > epsilon$2) {
      if (abs$1(sa1 - sa0) > ap * 2 + epsilon$2) sa1 > sa0 ? (sa0 += ap, sa1 -= ap) : (sa0 -= ap, sa1 += ap);
      else sa0 = sa1 = (sa0 + sa1) / 2;
      if (abs$1(ta1 - ta0) > ap * 2 + epsilon$2) ta1 > ta0 ? (ta0 += ap, ta1 -= ap) : (ta0 -= ap, ta1 += ap);
      else ta0 = ta1 = (ta0 + ta1) / 2;
    }

    context.moveTo(sr * cos$1(sa0), sr * sin$1(sa0));
    context.arc(0, 0, sr, sa0, sa1);
    if (sa0 !== ta0 || sa1 !== ta1) {
      if (headRadius) {
        var hr = +headRadius.apply(this, arguments), tr2 = tr - hr, ta2 = (ta0 + ta1) / 2;
        context.quadraticCurveTo(0, 0, tr2 * cos$1(ta0), tr2 * sin$1(ta0));
        context.lineTo(tr * cos$1(ta2), tr * sin$1(ta2));
        context.lineTo(tr2 * cos$1(ta1), tr2 * sin$1(ta1));
      } else {
        context.quadraticCurveTo(0, 0, tr * cos$1(ta0), tr * sin$1(ta0));
        context.arc(0, 0, tr, ta0, ta1);
      }
    }
    context.quadraticCurveTo(0, 0, sr * cos$1(sa0), sr * sin$1(sa0));
    context.closePath();

    if (buffer) return context = null, buffer + "" || null;
  }

  if (headRadius) ribbon.headRadius = function(_) {
    return arguments.length ? (headRadius = typeof _ === "function" ? _ : constant$4(+_), ribbon) : headRadius;
  };

  ribbon.radius = function(_) {
    return arguments.length ? (sourceRadius = targetRadius = typeof _ === "function" ? _ : constant$4(+_), ribbon) : sourceRadius;
  };

  ribbon.sourceRadius = function(_) {
    return arguments.length ? (sourceRadius = typeof _ === "function" ? _ : constant$4(+_), ribbon) : sourceRadius;
  };

  ribbon.targetRadius = function(_) {
    return arguments.length ? (targetRadius = typeof _ === "function" ? _ : constant$4(+_), ribbon) : targetRadius;
  };

  ribbon.startAngle = function(_) {
    return arguments.length ? (startAngle = typeof _ === "function" ? _ : constant$4(+_), ribbon) : startAngle;
  };

  ribbon.endAngle = function(_) {
    return arguments.length ? (endAngle = typeof _ === "function" ? _ : constant$4(+_), ribbon) : endAngle;
  };

  ribbon.padAngle = function(_) {
    return arguments.length ? (padAngle = typeof _ === "function" ? _ : constant$4(+_), ribbon) : padAngle;
  };

  ribbon.source = function(_) {
    return arguments.length ? (source = _, ribbon) : source;
  };

  ribbon.target = function(_) {
    return arguments.length ? (target = _, ribbon) : target;
  };

  ribbon.context = function(_) {
    return arguments.length ? ((context = _ == null ? null : _), ribbon) : context;
  };

  return ribbon;
}

function ribbon$1() {
  return ribbon();
}

function ribbonArrow() {
  return ribbon(defaultArrowheadRadius);
}

var noop = {value: () => {}};

function dispatch() {
  for (var i = 0, n = arguments.length, _ = {}, t; i < n; ++i) {
    if (!(t = arguments[i] + "") || (t in _) || /[\s.]/.test(t)) throw new Error("illegal type: " + t);
    _[t] = [];
  }
  return new Dispatch(_);
}

function Dispatch(_) {
  this._ = _;
}

function parseTypenames$1(typenames, types) {
  return typenames.trim().split(/^|\s+/).map(function(t) {
    var name = "", i = t.indexOf(".");
    if (i >= 0) name = t.slice(i + 1), t = t.slice(0, i);
    if (t && !types.hasOwnProperty(t)) throw new Error("unknown type: " + t);
    return {type: t, name: name};
  });
}

Dispatch.prototype = dispatch.prototype = {
  constructor: Dispatch,
  on: function(typename, callback) {
    var _ = this._,
        T = parseTypenames$1(typename + "", _),
        t,
        i = -1,
        n = T.length;

    // If no callback was specified, return the callback of the given type and name.
    if (arguments.length < 2) {
      while (++i < n) if ((t = (typename = T[i]).type) && (t = get$1(_[t], typename.name))) return t;
      return;
    }

    // If a type was specified, set the callback for the given type and name.
    // Otherwise, if a null callback was specified, remove callbacks of the given name.
    if (callback != null && typeof callback !== "function") throw new Error("invalid callback: " + callback);
    while (++i < n) {
      if (t = (typename = T[i]).type) _[t] = set$1(_[t], typename.name, callback);
      else if (callback == null) for (t in _) _[t] = set$1(_[t], typename.name, null);
    }

    return this;
  },
  copy: function() {
    var copy = {}, _ = this._;
    for (var t in _) copy[t] = _[t].slice();
    return new Dispatch(copy);
  },
  call: function(type, that) {
    if ((n = arguments.length - 2) > 0) for (var args = new Array(n), i = 0, n, t; i < n; ++i) args[i] = arguments[i + 2];
    if (!this._.hasOwnProperty(type)) throw new Error("unknown type: " + type);
    for (t = this._[type], i = 0, n = t.length; i < n; ++i) t[i].value.apply(that, args);
  },
  apply: function(type, that, args) {
    if (!this._.hasOwnProperty(type)) throw new Error("unknown type: " + type);
    for (var t = this._[type], i = 0, n = t.length; i < n; ++i) t[i].value.apply(that, args);
  }
};

function get$1(type, name) {
  for (var i = 0, n = type.length, c; i < n; ++i) {
    if ((c = type[i]).name === name) {
      return c.value;
    }
  }
}

function set$1(type, name, callback) {
  for (var i = 0, n = type.length; i < n; ++i) {
    if (type[i].name === name) {
      type[i] = noop, type = type.slice(0, i).concat(type.slice(i + 1));
      break;
    }
  }
  if (callback != null) type.push({name: name, value: callback});
  return type;
}

var xhtml = "http://www.w3.org/1999/xhtml";

var namespaces = {
  svg: "http://www.w3.org/2000/svg",
  xhtml: xhtml,
  xlink: "http://www.w3.org/1999/xlink",
  xml: "http://www.w3.org/XML/1998/namespace",
  xmlns: "http://www.w3.org/2000/xmlns/"
};

function namespace(name) {
  var prefix = name += "", i = prefix.indexOf(":");
  if (i >= 0 && (prefix = name.slice(0, i)) !== "xmlns") name = name.slice(i + 1);
  return namespaces.hasOwnProperty(prefix) ? {space: namespaces[prefix], local: name} : name; // eslint-disable-line no-prototype-builtins
}

function creatorInherit(name) {
  return function() {
    var document = this.ownerDocument,
        uri = this.namespaceURI;
    return uri === xhtml && document.documentElement.namespaceURI === xhtml
        ? document.createElement(name)
        : document.createElementNS(uri, name);
  };
}

function creatorFixed(fullname) {
  return function() {
    return this.ownerDocument.createElementNS(fullname.space, fullname.local);
  };
}

function creator(name) {
  var fullname = namespace(name);
  return (fullname.local
      ? creatorFixed
      : creatorInherit)(fullname);
}

function none() {}

function selector(selector) {
  return selector == null ? none : function() {
    return this.querySelector(selector);
  };
}

function selection_select(select) {
  if (typeof select !== "function") select = selector(select);

  for (var groups = this._groups, m = groups.length, subgroups = new Array(m), j = 0; j < m; ++j) {
    for (var group = groups[j], n = group.length, subgroup = subgroups[j] = new Array(n), node, subnode, i = 0; i < n; ++i) {
      if ((node = group[i]) && (subnode = select.call(node, node.__data__, i, group))) {
        if ("__data__" in node) subnode.__data__ = node.__data__;
        subgroup[i] = subnode;
      }
    }
  }

  return new Selection$1(subgroups, this._parents);
}

// Given something array like (or null), returns something that is strictly an
// array. This is used to ensure that array-like objects passed to d3.selectAll
// or selection.selectAll are converted into proper arrays when creating a
// selection; we don’t ever want to create a selection backed by a live
// HTMLCollection or NodeList. However, note that selection.selectAll will use a
// static NodeList as a group, since it safely derived from querySelectorAll.
function array(x) {
  return x == null ? [] : Array.isArray(x) ? x : Array.from(x);
}

function empty() {
  return [];
}

function selectorAll(selector) {
  return selector == null ? empty : function() {
    return this.querySelectorAll(selector);
  };
}

function arrayAll(select) {
  return function() {
    return array(select.apply(this, arguments));
  };
}

function selection_selectAll(select) {
  if (typeof select === "function") select = arrayAll(select);
  else select = selectorAll(select);

  for (var groups = this._groups, m = groups.length, subgroups = [], parents = [], j = 0; j < m; ++j) {
    for (var group = groups[j], n = group.length, node, i = 0; i < n; ++i) {
      if (node = group[i]) {
        subgroups.push(select.call(node, node.__data__, i, group));
        parents.push(node);
      }
    }
  }

  return new Selection$1(subgroups, parents);
}

function matcher(selector) {
  return function() {
    return this.matches(selector);
  };
}

function childMatcher(selector) {
  return function(node) {
    return node.matches(selector);
  };
}

var find = Array.prototype.find;

function childFind(match) {
  return function() {
    return find.call(this.children, match);
  };
}

function childFirst() {
  return this.firstElementChild;
}

function selection_selectChild(match) {
  return this.select(match == null ? childFirst
      : childFind(typeof match === "function" ? match : childMatcher(match)));
}

var filter = Array.prototype.filter;

function children() {
  return Array.from(this.children);
}

function childrenFilter(match) {
  return function() {
    return filter.call(this.children, match);
  };
}

function selection_selectChildren(match) {
  return this.selectAll(match == null ? children
      : childrenFilter(typeof match === "function" ? match : childMatcher(match)));
}

function selection_filter(match) {
  if (typeof match !== "function") match = matcher(match);

  for (var groups = this._groups, m = groups.length, subgroups = new Array(m), j = 0; j < m; ++j) {
    for (var group = groups[j], n = group.length, subgroup = subgroups[j] = [], node, i = 0; i < n; ++i) {
      if ((node = group[i]) && match.call(node, node.__data__, i, group)) {
        subgroup.push(node);
      }
    }
  }

  return new Selection$1(subgroups, this._parents);
}

function sparse(update) {
  return new Array(update.length);
}

function selection_enter() {
  return new Selection$1(this._enter || this._groups.map(sparse), this._parents);
}

function EnterNode(parent, datum) {
  this.ownerDocument = parent.ownerDocument;
  this.namespaceURI = parent.namespaceURI;
  this._next = null;
  this._parent = parent;
  this.__data__ = datum;
}

EnterNode.prototype = {
  constructor: EnterNode,
  appendChild: function(child) { return this._parent.insertBefore(child, this._next); },
  insertBefore: function(child, next) { return this._parent.insertBefore(child, next); },
  querySelector: function(selector) { return this._parent.querySelector(selector); },
  querySelectorAll: function(selector) { return this._parent.querySelectorAll(selector); }
};

function constant$3(x) {
  return function() {
    return x;
  };
}

function bindIndex(parent, group, enter, update, exit, data) {
  var i = 0,
      node,
      groupLength = group.length,
      dataLength = data.length;

  // Put any non-null nodes that fit into update.
  // Put any null nodes into enter.
  // Put any remaining data into enter.
  for (; i < dataLength; ++i) {
    if (node = group[i]) {
      node.__data__ = data[i];
      update[i] = node;
    } else {
      enter[i] = new EnterNode(parent, data[i]);
    }
  }

  // Put any non-null nodes that don’t fit into exit.
  for (; i < groupLength; ++i) {
    if (node = group[i]) {
      exit[i] = node;
    }
  }
}

function bindKey(parent, group, enter, update, exit, data, key) {
  var i,
      node,
      nodeByKeyValue = new Map,
      groupLength = group.length,
      dataLength = data.length,
      keyValues = new Array(groupLength),
      keyValue;

  // Compute the key for each node.
  // If multiple nodes have the same key, the duplicates are added to exit.
  for (i = 0; i < groupLength; ++i) {
    if (node = group[i]) {
      keyValues[i] = keyValue = key.call(node, node.__data__, i, group) + "";
      if (nodeByKeyValue.has(keyValue)) {
        exit[i] = node;
      } else {
        nodeByKeyValue.set(keyValue, node);
      }
    }
  }

  // Compute the key for each datum.
  // If there a node associated with this key, join and add it to update.
  // If there is not (or the key is a duplicate), add it to enter.
  for (i = 0; i < dataLength; ++i) {
    keyValue = key.call(parent, data[i], i, data) + "";
    if (node = nodeByKeyValue.get(keyValue)) {
      update[i] = node;
      node.__data__ = data[i];
      nodeByKeyValue.delete(keyValue);
    } else {
      enter[i] = new EnterNode(parent, data[i]);
    }
  }

  // Add any remaining nodes that were not bound to data to exit.
  for (i = 0; i < groupLength; ++i) {
    if ((node = group[i]) && (nodeByKeyValue.get(keyValues[i]) === node)) {
      exit[i] = node;
    }
  }
}

function datum(node) {
  return node.__data__;
}

function selection_data(value, key) {
  if (!arguments.length) return Array.from(this, datum);

  var bind = key ? bindKey : bindIndex,
      parents = this._parents,
      groups = this._groups;

  if (typeof value !== "function") value = constant$3(value);

  for (var m = groups.length, update = new Array(m), enter = new Array(m), exit = new Array(m), j = 0; j < m; ++j) {
    var parent = parents[j],
        group = groups[j],
        groupLength = group.length,
        data = arraylike(value.call(parent, parent && parent.__data__, j, parents)),
        dataLength = data.length,
        enterGroup = enter[j] = new Array(dataLength),
        updateGroup = update[j] = new Array(dataLength),
        exitGroup = exit[j] = new Array(groupLength);

    bind(parent, group, enterGroup, updateGroup, exitGroup, data, key);

    // Now connect the enter nodes to their following update node, such that
    // appendChild can insert the materialized enter node before this node,
    // rather than at the end of the parent node.
    for (var i0 = 0, i1 = 0, previous, next; i0 < dataLength; ++i0) {
      if (previous = enterGroup[i0]) {
        if (i0 >= i1) i1 = i0 + 1;
        while (!(next = updateGroup[i1]) && ++i1 < dataLength);
        previous._next = next || null;
      }
    }
  }

  update = new Selection$1(update, parents);
  update._enter = enter;
  update._exit = exit;
  return update;
}

// Given some data, this returns an array-like view of it: an object that
// exposes a length property and allows numeric indexing. Note that unlike
// selectAll, this isn’t worried about “live” collections because the resulting
// array will only be used briefly while data is being bound. (It is possible to
// cause the data to change while iterating by using a key function, but please
// don’t; we’d rather avoid a gratuitous copy.)
function arraylike(data) {
  return typeof data === "object" && "length" in data
    ? data // Array, TypedArray, NodeList, array-like
    : Array.from(data); // Map, Set, iterable, string, or anything else
}

function selection_exit() {
  return new Selection$1(this._exit || this._groups.map(sparse), this._parents);
}

function selection_join(onenter, onupdate, onexit) {
  var enter = this.enter(), update = this, exit = this.exit();
  if (typeof onenter === "function") {
    enter = onenter(enter);
    if (enter) enter = enter.selection();
  } else {
    enter = enter.append(onenter + "");
  }
  if (onupdate != null) {
    update = onupdate(update);
    if (update) update = update.selection();
  }
  if (onexit == null) exit.remove(); else onexit(exit);
  return enter && update ? enter.merge(update).order() : update;
}

function selection_merge(context) {
  var selection = context.selection ? context.selection() : context;

  for (var groups0 = this._groups, groups1 = selection._groups, m0 = groups0.length, m1 = groups1.length, m = Math.min(m0, m1), merges = new Array(m0), j = 0; j < m; ++j) {
    for (var group0 = groups0[j], group1 = groups1[j], n = group0.length, merge = merges[j] = new Array(n), node, i = 0; i < n; ++i) {
      if (node = group0[i] || group1[i]) {
        merge[i] = node;
      }
    }
  }

  for (; j < m0; ++j) {
    merges[j] = groups0[j];
  }

  return new Selection$1(merges, this._parents);
}

function selection_order() {

  for (var groups = this._groups, j = -1, m = groups.length; ++j < m;) {
    for (var group = groups[j], i = group.length - 1, next = group[i], node; --i >= 0;) {
      if (node = group[i]) {
        if (next && node.compareDocumentPosition(next) ^ 4) next.parentNode.insertBefore(node, next);
        next = node;
      }
    }
  }

  return this;
}

function selection_sort(compare) {
  if (!compare) compare = ascending$1;

  function compareNode(a, b) {
    return a && b ? compare(a.__data__, b.__data__) : !a - !b;
  }

  for (var groups = this._groups, m = groups.length, sortgroups = new Array(m), j = 0; j < m; ++j) {
    for (var group = groups[j], n = group.length, sortgroup = sortgroups[j] = new Array(n), node, i = 0; i < n; ++i) {
      if (node = group[i]) {
        sortgroup[i] = node;
      }
    }
    sortgroup.sort(compareNode);
  }

  return new Selection$1(sortgroups, this._parents).order();
}

function ascending$1(a, b) {
  return a < b ? -1 : a > b ? 1 : a >= b ? 0 : NaN;
}

function selection_call() {
  var callback = arguments[0];
  arguments[0] = this;
  callback.apply(null, arguments);
  return this;
}

function selection_nodes() {
  return Array.from(this);
}

function selection_node() {

  for (var groups = this._groups, j = 0, m = groups.length; j < m; ++j) {
    for (var group = groups[j], i = 0, n = group.length; i < n; ++i) {
      var node = group[i];
      if (node) return node;
    }
  }

  return null;
}

function selection_size() {
  let size = 0;
  for (const node of this) ++size; // eslint-disable-line no-unused-vars
  return size;
}

function selection_empty() {
  return !this.node();
}

function selection_each(callback) {

  for (var groups = this._groups, j = 0, m = groups.length; j < m; ++j) {
    for (var group = groups[j], i = 0, n = group.length, node; i < n; ++i) {
      if (node = group[i]) callback.call(node, node.__data__, i, group);
    }
  }

  return this;
}

function attrRemove$1(name) {
  return function() {
    this.removeAttribute(name);
  };
}

function attrRemoveNS$1(fullname) {
  return function() {
    this.removeAttributeNS(fullname.space, fullname.local);
  };
}

function attrConstant$1(name, value) {
  return function() {
    this.setAttribute(name, value);
  };
}

function attrConstantNS$1(fullname, value) {
  return function() {
    this.setAttributeNS(fullname.space, fullname.local, value);
  };
}

function attrFunction$1(name, value) {
  return function() {
    var v = value.apply(this, arguments);
    if (v == null) this.removeAttribute(name);
    else this.setAttribute(name, v);
  };
}

function attrFunctionNS$1(fullname, value) {
  return function() {
    var v = value.apply(this, arguments);
    if (v == null) this.removeAttributeNS(fullname.space, fullname.local);
    else this.setAttributeNS(fullname.space, fullname.local, v);
  };
}

function selection_attr(name, value) {
  var fullname = namespace(name);

  if (arguments.length < 2) {
    var node = this.node();
    return fullname.local
        ? node.getAttributeNS(fullname.space, fullname.local)
        : node.getAttribute(fullname);
  }

  return this.each((value == null
      ? (fullname.local ? attrRemoveNS$1 : attrRemove$1) : (typeof value === "function"
      ? (fullname.local ? attrFunctionNS$1 : attrFunction$1)
      : (fullname.local ? attrConstantNS$1 : attrConstant$1)))(fullname, value));
}

function defaultView(node) {
  return (node.ownerDocument && node.ownerDocument.defaultView) // node is a Node
      || (node.document && node) // node is a Window
      || node.defaultView; // node is a Document
}

function styleRemove$1(name) {
  return function() {
    this.style.removeProperty(name);
  };
}

function styleConstant$1(name, value, priority) {
  return function() {
    this.style.setProperty(name, value, priority);
  };
}

function styleFunction$1(name, value, priority) {
  return function() {
    var v = value.apply(this, arguments);
    if (v == null) this.style.removeProperty(name);
    else this.style.setProperty(name, v, priority);
  };
}

function selection_style(name, value, priority) {
  return arguments.length > 1
      ? this.each((value == null
            ? styleRemove$1 : typeof value === "function"
            ? styleFunction$1
            : styleConstant$1)(name, value, priority == null ? "" : priority))
      : styleValue(this.node(), name);
}

function styleValue(node, name) {
  return node.style.getPropertyValue(name)
      || defaultView(node).getComputedStyle(node, null).getPropertyValue(name);
}

function propertyRemove(name) {
  return function() {
    delete this[name];
  };
}

function propertyConstant(name, value) {
  return function() {
    this[name] = value;
  };
}

function propertyFunction(name, value) {
  return function() {
    var v = value.apply(this, arguments);
    if (v == null) delete this[name];
    else this[name] = v;
  };
}

function selection_property(name, value) {
  return arguments.length > 1
      ? this.each((value == null
          ? propertyRemove : typeof value === "function"
          ? propertyFunction
          : propertyConstant)(name, value))
      : this.node()[name];
}

function classArray(string) {
  return string.trim().split(/^|\s+/);
}

function classList(node) {
  return node.classList || new ClassList(node);
}

function ClassList(node) {
  this._node = node;
  this._names = classArray(node.getAttribute("class") || "");
}

ClassList.prototype = {
  add: function(name) {
    var i = this._names.indexOf(name);
    if (i < 0) {
      this._names.push(name);
      this._node.setAttribute("class", this._names.join(" "));
    }
  },
  remove: function(name) {
    var i = this._names.indexOf(name);
    if (i >= 0) {
      this._names.splice(i, 1);
      this._node.setAttribute("class", this._names.join(" "));
    }
  },
  contains: function(name) {
    return this._names.indexOf(name) >= 0;
  }
};

function classedAdd(node, names) {
  var list = classList(node), i = -1, n = names.length;
  while (++i < n) list.add(names[i]);
}

function classedRemove(node, names) {
  var list = classList(node), i = -1, n = names.length;
  while (++i < n) list.remove(names[i]);
}

function classedTrue(names) {
  return function() {
    classedAdd(this, names);
  };
}

function classedFalse(names) {
  return function() {
    classedRemove(this, names);
  };
}

function classedFunction(names, value) {
  return function() {
    (value.apply(this, arguments) ? classedAdd : classedRemove)(this, names);
  };
}

function selection_classed(name, value) {
  var names = classArray(name + "");

  if (arguments.length < 2) {
    var list = classList(this.node()), i = -1, n = names.length;
    while (++i < n) if (!list.contains(names[i])) return false;
    return true;
  }

  return this.each((typeof value === "function"
      ? classedFunction : value
      ? classedTrue
      : classedFalse)(names, value));
}

function textRemove() {
  this.textContent = "";
}

function textConstant$1(value) {
  return function() {
    this.textContent = value;
  };
}

function textFunction$1(value) {
  return function() {
    var v = value.apply(this, arguments);
    this.textContent = v == null ? "" : v;
  };
}

function selection_text(value) {
  return arguments.length
      ? this.each(value == null
          ? textRemove : (typeof value === "function"
          ? textFunction$1
          : textConstant$1)(value))
      : this.node().textContent;
}

function htmlRemove() {
  this.innerHTML = "";
}

function htmlConstant(value) {
  return function() {
    this.innerHTML = value;
  };
}

function htmlFunction(value) {
  return function() {
    var v = value.apply(this, arguments);
    this.innerHTML = v == null ? "" : v;
  };
}

function selection_html(value) {
  return arguments.length
      ? this.each(value == null
          ? htmlRemove : (typeof value === "function"
          ? htmlFunction
          : htmlConstant)(value))
      : this.node().innerHTML;
}

function raise() {
  if (this.nextSibling) this.parentNode.appendChild(this);
}

function selection_raise() {
  return this.each(raise);
}

function lower() {
  if (this.previousSibling) this.parentNode.insertBefore(this, this.parentNode.firstChild);
}

function selection_lower() {
  return this.each(lower);
}

function selection_append(name) {
  var create = typeof name === "function" ? name : creator(name);
  return this.select(function() {
    return this.appendChild(create.apply(this, arguments));
  });
}

function constantNull() {
  return null;
}

function selection_insert(name, before) {
  var create = typeof name === "function" ? name : creator(name),
      select = before == null ? constantNull : typeof before === "function" ? before : selector(before);
  return this.select(function() {
    return this.insertBefore(create.apply(this, arguments), select.apply(this, arguments) || null);
  });
}

function remove() {
  var parent = this.parentNode;
  if (parent) parent.removeChild(this);
}

function selection_remove() {
  return this.each(remove);
}

function selection_cloneShallow() {
  var clone = this.cloneNode(false), parent = this.parentNode;
  return parent ? parent.insertBefore(clone, this.nextSibling) : clone;
}

function selection_cloneDeep() {
  var clone = this.cloneNode(true), parent = this.parentNode;
  return parent ? parent.insertBefore(clone, this.nextSibling) : clone;
}

function selection_clone(deep) {
  return this.select(deep ? selection_cloneDeep : selection_cloneShallow);
}

function selection_datum(value) {
  return arguments.length
      ? this.property("__data__", value)
      : this.node().__data__;
}

function contextListener(listener) {
  return function(event) {
    listener.call(this, event, this.__data__);
  };
}

function parseTypenames(typenames) {
  return typenames.trim().split(/^|\s+/).map(function(t) {
    var name = "", i = t.indexOf(".");
    if (i >= 0) name = t.slice(i + 1), t = t.slice(0, i);
    return {type: t, name: name};
  });
}

function onRemove(typename) {
  return function() {
    var on = this.__on;
    if (!on) return;
    for (var j = 0, i = -1, m = on.length, o; j < m; ++j) {
      if (o = on[j], (!typename.type || o.type === typename.type) && o.name === typename.name) {
        this.removeEventListener(o.type, o.listener, o.options);
      } else {
        on[++i] = o;
      }
    }
    if (++i) on.length = i;
    else delete this.__on;
  };
}

function onAdd(typename, value, options) {
  return function() {
    var on = this.__on, o, listener = contextListener(value);
    if (on) for (var j = 0, m = on.length; j < m; ++j) {
      if ((o = on[j]).type === typename.type && o.name === typename.name) {
        this.removeEventListener(o.type, o.listener, o.options);
        this.addEventListener(o.type, o.listener = listener, o.options = options);
        o.value = value;
        return;
      }
    }
    this.addEventListener(typename.type, listener, options);
    o = {type: typename.type, name: typename.name, value: value, listener: listener, options: options};
    if (!on) this.__on = [o];
    else on.push(o);
  };
}

function selection_on(typename, value, options) {
  var typenames = parseTypenames(typename + ""), i, n = typenames.length, t;

  if (arguments.length < 2) {
    var on = this.node().__on;
    if (on) for (var j = 0, m = on.length, o; j < m; ++j) {
      for (i = 0, o = on[j]; i < n; ++i) {
        if ((t = typenames[i]).type === o.type && t.name === o.name) {
          return o.value;
        }
      }
    }
    return;
  }

  on = value ? onAdd : onRemove;
  for (i = 0; i < n; ++i) this.each(on(typenames[i], value, options));
  return this;
}

function dispatchEvent(node, type, params) {
  var window = defaultView(node),
      event = window.CustomEvent;

  if (typeof event === "function") {
    event = new event(type, params);
  } else {
    event = window.document.createEvent("Event");
    if (params) event.initEvent(type, params.bubbles, params.cancelable), event.detail = params.detail;
    else event.initEvent(type, false, false);
  }

  node.dispatchEvent(event);
}

function dispatchConstant(type, params) {
  return function() {
    return dispatchEvent(this, type, params);
  };
}

function dispatchFunction(type, params) {
  return function() {
    return dispatchEvent(this, type, params.apply(this, arguments));
  };
}

function selection_dispatch(type, params) {
  return this.each((typeof params === "function"
      ? dispatchFunction
      : dispatchConstant)(type, params));
}

function* selection_iterator() {
  for (var groups = this._groups, j = 0, m = groups.length; j < m; ++j) {
    for (var group = groups[j], i = 0, n = group.length, node; i < n; ++i) {
      if (node = group[i]) yield node;
    }
  }
}

var root$1 = [null];

function Selection$1(groups, parents) {
  this._groups = groups;
  this._parents = parents;
}

function selection() {
  return new Selection$1([[document.documentElement]], root$1);
}

function selection_selection() {
  return this;
}

Selection$1.prototype = selection.prototype = {
  constructor: Selection$1,
  select: selection_select,
  selectAll: selection_selectAll,
  selectChild: selection_selectChild,
  selectChildren: selection_selectChildren,
  filter: selection_filter,
  data: selection_data,
  enter: selection_enter,
  exit: selection_exit,
  join: selection_join,
  merge: selection_merge,
  selection: selection_selection,
  order: selection_order,
  sort: selection_sort,
  call: selection_call,
  nodes: selection_nodes,
  node: selection_node,
  size: selection_size,
  empty: selection_empty,
  each: selection_each,
  attr: selection_attr,
  style: selection_style,
  property: selection_property,
  classed: selection_classed,
  text: selection_text,
  html: selection_html,
  raise: selection_raise,
  lower: selection_lower,
  append: selection_append,
  insert: selection_insert,
  remove: selection_remove,
  clone: selection_clone,
  datum: selection_datum,
  on: selection_on,
  dispatch: selection_dispatch,
  [Symbol.iterator]: selection_iterator
};

function select(selector) {
  return typeof selector === "string"
      ? new Selection$1([[document.querySelector(selector)]], [document.documentElement])
      : new Selection$1([[selector]], root$1);
}

function create$1(name) {
  return select(creator(name).call(document.documentElement));
}

var nextId = 0;

function local() {
  return new Local;
}

function Local() {
  this._ = "@" + (++nextId).toString(36);
}

Local.prototype = local.prototype = {
  constructor: Local,
  get: function(node) {
    var id = this._;
    while (!(id in node)) if (!(node = node.parentNode)) return;
    return node[id];
  },
  set: function(node, value) {
    return node[this._] = value;
  },
  remove: function(node) {
    return this._ in node && delete node[this._];
  },
  toString: function() {
    return this._;
  }
};

function sourceEvent(event) {
  let sourceEvent;
  while (sourceEvent = event.sourceEvent) event = sourceEvent;
  return event;
}

function pointer(event, node) {
  event = sourceEvent(event);
  if (node === undefined) node = event.currentTarget;
  if (node) {
    var svg = node.ownerSVGElement || node;
    if (svg.createSVGPoint) {
      var point = svg.createSVGPoint();
      point.x = event.clientX, point.y = event.clientY;
      point = point.matrixTransform(node.getScreenCTM().inverse());
      return [point.x, point.y];
    }
    if (node.getBoundingClientRect) {
      var rect = node.getBoundingClientRect();
      return [event.clientX - rect.left - node.clientLeft, event.clientY - rect.top - node.clientTop];
    }
  }
  return [event.pageX, event.pageY];
}

function pointers(events, node) {
  if (events.target) { // i.e., instanceof Event, not TouchList or iterable
    events = sourceEvent(events);
    if (node === undefined) node = events.currentTarget;
    events = events.touches || [events];
  }
  return Array.from(events, event => pointer(event, node));
}

function selectAll(selector) {
  return typeof selector === "string"
      ? new Selection$1([document.querySelectorAll(selector)], [document.documentElement])
      : new Selection$1([array(selector)], root$1);
}

// These are typically used in conjunction with noevent to ensure that we can
// preventDefault on the event.
const nonpassive = {passive: false};
const nonpassivecapture = {capture: true, passive: false};

function nopropagation(event) {
  event.stopImmediatePropagation();
}

function noevent(event) {
  event.preventDefault();
  event.stopImmediatePropagation();
}

function nodrag(view) {
  var root = view.document.documentElement,
      selection = select(view).on("dragstart.drag", noevent, nonpassivecapture);
  if ("onselectstart" in root) {
    selection.on("selectstart.drag", noevent, nonpassivecapture);
  } else {
    root.__noselect = root.style.MozUserSelect;
    root.style.MozUserSelect = "none";
  }
}

function yesdrag(view, noclick) {
  var root = view.document.documentElement,
      selection = select(view).on("dragstart.drag", null);
  if (noclick) {
    selection.on("click.drag", noevent, nonpassivecapture);
    setTimeout(function() { selection.on("click.drag", null); }, 0);
  }
  if ("onselectstart" in root) {
    selection.on("selectstart.drag", null);
  } else {
    root.style.MozUserSelect = root.__noselect;
    delete root.__noselect;
  }
}

var constant$2 = x => () => x;

function DragEvent(type, {
  sourceEvent,
  subject,
  target,
  identifier,
  active,
  x, y, dx, dy,
  dispatch
}) {
  Object.defineProperties(this, {
    type: {value: type, enumerable: true, configurable: true},
    sourceEvent: {value: sourceEvent, enumerable: true, configurable: true},
    subject: {value: subject, enumerable: true, configurable: true},
    target: {value: target, enumerable: true, configurable: true},
    identifier: {value: identifier, enumerable: true, configurable: true},
    active: {value: active, enumerable: true, configurable: true},
    x: {value: x, enumerable: true, configurable: true},
    y: {value: y, enumerable: true, configurable: true},
    dx: {value: dx, enumerable: true, configurable: true},
    dy: {value: dy, enumerable: true, configurable: true},
    _: {value: dispatch}
  });
}

DragEvent.prototype.on = function() {
  var value = this._.on.apply(this._, arguments);
  return value === this._ ? this : value;
};

// Ignore right-click, since that should open the context menu.
function defaultFilter(event) {
  return !event.ctrlKey && !event.button;
}

function defaultContainer() {
  return this.parentNode;
}

function defaultSubject(event, d) {
  return d == null ? {x: event.x, y: event.y} : d;
}

function defaultTouchable() {
  return navigator.maxTouchPoints || ("ontouchstart" in this);
}

function drag() {
  var filter = defaultFilter,
      container = defaultContainer,
      subject = defaultSubject,
      touchable = defaultTouchable,
      gestures = {},
      listeners = dispatch("start", "drag", "end"),
      active = 0,
      mousedownx,
      mousedowny,
      mousemoving,
      touchending,
      clickDistance2 = 0;

  function drag(selection) {
    selection
        .on("mousedown.drag", mousedowned)
      .filter(touchable)
        .on("touchstart.drag", touchstarted)
        .on("touchmove.drag", touchmoved, nonpassive)
        .on("touchend.drag touchcancel.drag", touchended)
        .style("touch-action", "none")
        .style("-webkit-tap-highlight-color", "rgba(0,0,0,0)");
  }

  function mousedowned(event, d) {
    if (touchending || !filter.call(this, event, d)) return;
    var gesture = beforestart(this, container.call(this, event, d), event, d, "mouse");
    if (!gesture) return;
    select(event.view)
      .on("mousemove.drag", mousemoved, nonpassivecapture)
      .on("mouseup.drag", mouseupped, nonpassivecapture);
    nodrag(event.view);
    nopropagation(event);
    mousemoving = false;
    mousedownx = event.clientX;
    mousedowny = event.clientY;
    gesture("start", event);
  }

  function mousemoved(event) {
    noevent(event);
    if (!mousemoving) {
      var dx = event.clientX - mousedownx, dy = event.clientY - mousedowny;
      mousemoving = dx * dx + dy * dy > clickDistance2;
    }
    gestures.mouse("drag", event);
  }

  function mouseupped(event) {
    select(event.view).on("mousemove.drag mouseup.drag", null);
    yesdrag(event.view, mousemoving);
    noevent(event);
    gestures.mouse("end", event);
  }

  function touchstarted(event, d) {
    if (!filter.call(this, event, d)) return;
    var touches = event.changedTouches,
        c = container.call(this, event, d),
        n = touches.length, i, gesture;

    for (i = 0; i < n; ++i) {
      if (gesture = beforestart(this, c, event, d, touches[i].identifier, touches[i])) {
        nopropagation(event);
        gesture("start", event, touches[i]);
      }
    }
  }

  function touchmoved(event) {
    var touches = event.changedTouches,
        n = touches.length, i, gesture;

    for (i = 0; i < n; ++i) {
      if (gesture = gestures[touches[i].identifier]) {
        noevent(event);
        gesture("drag", event, touches[i]);
      }
    }
  }

  function touchended(event) {
    var touches = event.changedTouches,
        n = touches.length, i, gesture;

    if (touchending) clearTimeout(touchending);
    touchending = setTimeout(function() { touchending = null; }, 500); // Ghost clicks are delayed!
    for (i = 0; i < n; ++i) {
      if (gesture = gestures[touches[i].identifier]) {
        nopropagation(event);
        gesture("end", event, touches[i]);
      }
    }
  }

  function beforestart(that, container, event, d, identifier, touch) {
    var dispatch = listeners.copy(),
        p = pointer(touch || event, container), dx, dy,
        s;

    if ((s = subject.call(that, new DragEvent("beforestart", {
        sourceEvent: event,
        target: drag,
        identifier,
        active,
        x: p[0],
        y: p[1],
        dx: 0,
        dy: 0,
        dispatch
      }), d)) == null) return;

    dx = s.x - p[0] || 0;
    dy = s.y - p[1] || 0;

    return function gesture(type, event, touch) {
      var p0 = p, n;
      switch (type) {
        case "start": gestures[identifier] = gesture, n = active++; break;
        case "end": delete gestures[identifier], --active; // falls through
        case "drag": p = pointer(touch || event, container), n = active; break;
      }
      dispatch.call(
        type,
        that,
        new DragEvent(type, {
          sourceEvent: event,
          subject: s,
          target: drag,
          identifier,
          active: n,
          x: p[0] + dx,
          y: p[1] + dy,
          dx: p[0] - p0[0],
          dy: p[1] - p0[1],
          dispatch
        }),
        d
      );
    };
  }

  drag.filter = function(_) {
    return arguments.length ? (filter = typeof _ === "function" ? _ : constant$2(!!_), drag) : filter;
  };

  drag.container = function(_) {
    return arguments.length ? (container = typeof _ === "function" ? _ : constant$2(_), drag) : container;
  };

  drag.subject = function(_) {
    return arguments.length ? (subject = typeof _ === "function" ? _ : constant$2(_), drag) : subject;
  };

  drag.touchable = function(_) {
    return arguments.length ? (touchable = typeof _ === "function" ? _ : constant$2(!!_), drag) : touchable;
  };

  drag.on = function() {
    var value = listeners.on.apply(listeners, arguments);
    return value === listeners ? drag : value;
  };

  drag.clickDistance = function(_) {
    return arguments.length ? (clickDistance2 = (_ = +_) * _, drag) : Math.sqrt(clickDistance2);
  };

  return drag;
}

function ascending(a, b) {
  return a == null || b == null ? NaN : a < b ? -1 : a > b ? 1 : a >= b ? 0 : NaN;
}

function descending(a, b) {
  return a == null || b == null ? NaN
    : b < a ? -1
    : b > a ? 1
    : b >= a ? 0
    : NaN;
}

function bisector(f) {
  let compare1, compare2, delta;

  // If an accessor is specified, promote it to a comparator. In this case we
  // can test whether the search value is (self-) comparable. We can’t do this
  // for a comparator (except for specific, known comparators) because we can’t
  // tell if the comparator is symmetric, and an asymmetric comparator can’t be
  // used to test whether a single value is comparable.
  if (f.length !== 2) {
    compare1 = ascending;
    compare2 = (d, x) => ascending(f(d), x);
    delta = (d, x) => f(d) - x;
  } else {
    compare1 = f === ascending || f === descending ? f : zero$1;
    compare2 = f;
    delta = f;
  }

  function left(a, x, lo = 0, hi = a.length) {
    if (lo < hi) {
      if (compare1(x, x) !== 0) return hi;
      do {
        const mid = (lo + hi) >>> 1;
        if (compare2(a[mid], x) < 0) lo = mid + 1;
        else hi = mid;
      } while (lo < hi);
    }
    return lo;
  }

  function right(a, x, lo = 0, hi = a.length) {
    if (lo < hi) {
      if (compare1(x, x) !== 0) return hi;
      do {
        const mid = (lo + hi) >>> 1;
        if (compare2(a[mid], x) <= 0) lo = mid + 1;
        else hi = mid;
      } while (lo < hi);
    }
    return lo;
  }

  function center(a, x, lo = 0, hi = a.length) {
    const i = left(a, x, lo, hi - 1);
    return i > lo && delta(a[i - 1], x) > -delta(a[i], x) ? i - 1 : i;
  }

  return {left, center, right};
}

function zero$1() {
  return 0;
}

function number$2(x) {
  return x === null ? NaN : +x;
}

function* numbers(values, valueof) {
  {
    for (let value of values) {
      if (value != null && (value = +value) >= value) {
        yield value;
      }
    }
  }
}

const ascendingBisect = bisector(ascending);
const bisectRight = ascendingBisect.right;
bisector(number$2).center;

class InternMap extends Map {
  constructor(entries, key = keyof) {
    super();
    Object.defineProperties(this, {_intern: {value: new Map()}, _key: {value: key}});
    if (entries != null) for (const [key, value] of entries) this.set(key, value);
  }
  get(key) {
    return super.get(intern_get(this, key));
  }
  has(key) {
    return super.has(intern_get(this, key));
  }
  set(key, value) {
    return super.set(intern_set(this, key), value);
  }
  delete(key) {
    return super.delete(intern_delete(this, key));
  }
}

function intern_get({_intern, _key}, value) {
  const key = _key(value);
  return _intern.has(key) ? _intern.get(key) : value;
}

function intern_set({_intern, _key}, value) {
  const key = _key(value);
  if (_intern.has(key)) return _intern.get(key);
  _intern.set(key, value);
  return value;
}

function intern_delete({_intern, _key}, value) {
  const key = _key(value);
  if (_intern.has(key)) {
    value = _intern.get(key);
    _intern.delete(key);
  }
  return value;
}

function keyof(value) {
  return value !== null && typeof value === "object" ? value.valueOf() : value;
}

function compareDefined(compare = ascending) {
  if (compare === ascending) return ascendingDefined;
  if (typeof compare !== "function") throw new TypeError("compare is not a function");
  return (a, b) => {
    const x = compare(a, b);
    if (x || x === 0) return x;
    return (compare(b, b) === 0) - (compare(a, a) === 0);
  };
}

function ascendingDefined(a, b) {
  return (a == null || !(a >= a)) - (b == null || !(b >= b)) || (a < b ? -1 : a > b ? 1 : 0);
}

const e10 = Math.sqrt(50),
    e5 = Math.sqrt(10),
    e2 = Math.sqrt(2);

function tickSpec(start, stop, count) {
  const step = (stop - start) / Math.max(0, count),
      power = Math.floor(Math.log10(step)),
      error = step / Math.pow(10, power),
      factor = error >= e10 ? 10 : error >= e5 ? 5 : error >= e2 ? 2 : 1;
  let i1, i2, inc;
  if (power < 0) {
    inc = Math.pow(10, -power) / factor;
    i1 = Math.round(start * inc);
    i2 = Math.round(stop * inc);
    if (i1 / inc < start) ++i1;
    if (i2 / inc > stop) --i2;
    inc = -inc;
  } else {
    inc = Math.pow(10, power) * factor;
    i1 = Math.round(start / inc);
    i2 = Math.round(stop / inc);
    if (i1 * inc < start) ++i1;
    if (i2 * inc > stop) --i2;
  }
  if (i2 < i1 && 0.5 <= count && count < 2) return tickSpec(start, stop, count * 2);
  return [i1, i2, inc];
}

function ticks(start, stop, count) {
  stop = +stop, start = +start, count = +count;
  if (!(count > 0)) return [];
  if (start === stop) return [start];
  const reverse = stop < start, [i1, i2, inc] = reverse ? tickSpec(stop, start, count) : tickSpec(start, stop, count);
  if (!(i2 >= i1)) return [];
  const n = i2 - i1 + 1, ticks = new Array(n);
  if (reverse) {
    if (inc < 0) for (let i = 0; i < n; ++i) ticks[i] = (i2 - i) / -inc;
    else for (let i = 0; i < n; ++i) ticks[i] = (i2 - i) * inc;
  } else {
    if (inc < 0) for (let i = 0; i < n; ++i) ticks[i] = (i1 + i) / -inc;
    else for (let i = 0; i < n; ++i) ticks[i] = (i1 + i) * inc;
  }
  return ticks;
}

function tickIncrement(start, stop, count) {
  stop = +stop, start = +start, count = +count;
  return tickSpec(start, stop, count)[2];
}

function tickStep(start, stop, count) {
  stop = +stop, start = +start, count = +count;
  const reverse = stop < start, inc = reverse ? tickIncrement(stop, start, count) : tickIncrement(start, stop, count);
  return (reverse ? -1 : 1) * (inc < 0 ? 1 / -inc : inc);
}

function max$1(values, valueof) {
  let max;
  {
    for (const value of values) {
      if (value != null
          && (max < value || (max === undefined && value >= value))) {
        max = value;
      }
    }
  }
  return max;
}

function min$1(values, valueof) {
  let min;
  {
    for (const value of values) {
      if (value != null
          && (min > value || (min === undefined && value >= value))) {
        min = value;
      }
    }
  }
  return min;
}

// Based on https://github.com/mourner/quickselect
// ISC license, Copyright 2018 Vladimir Agafonkin.
function quickselect(array, k, left = 0, right = Infinity, compare) {
  k = Math.floor(k);
  left = Math.floor(Math.max(0, left));
  right = Math.floor(Math.min(array.length - 1, right));

  if (!(left <= k && k <= right)) return array;

  compare = compare === undefined ? ascendingDefined : compareDefined(compare);

  while (right > left) {
    if (right - left > 600) {
      const n = right - left + 1;
      const m = k - left + 1;
      const z = Math.log(n);
      const s = 0.5 * Math.exp(2 * z / 3);
      const sd = 0.5 * Math.sqrt(z * s * (n - s) / n) * (m - n / 2 < 0 ? -1 : 1);
      const newLeft = Math.max(left, Math.floor(k - m * s / n + sd));
      const newRight = Math.min(right, Math.floor(k + (n - m) * s / n + sd));
      quickselect(array, k, newLeft, newRight, compare);
    }

    const t = array[k];
    let i = left;
    let j = right;

    swap(array, left, k);
    if (compare(array[right], t) > 0) swap(array, left, right);

    while (i < j) {
      swap(array, i, j), ++i, --j;
      while (compare(array[i], t) < 0) ++i;
      while (compare(array[j], t) > 0) --j;
    }

    if (compare(array[left], t) === 0) swap(array, left, j);
    else ++j, swap(array, j, right);

    if (j <= k) left = j + 1;
    if (k <= j) right = j - 1;
  }

  return array;
}

function swap(array, i, j) {
  const t = array[i];
  array[i] = array[j];
  array[j] = t;
}

function quantile$1(values, p, valueof) {
  values = Float64Array.from(numbers(values));
  if (!(n = values.length) || isNaN(p = +p)) return;
  if (p <= 0 || n < 2) return min$1(values);
  if (p >= 1) return max$1(values);
  var n,
      i = (n - 1) * p,
      i0 = Math.floor(i),
      value0 = max$1(quickselect(values, i0).subarray(0, i0 + 1)),
      value1 = min$1(values.subarray(i0 + 1));
  return value0 + (value1 - value0) * (i - i0);
}

function quantileSorted(values, p, valueof = number$2) {
  if (!(n = values.length) || isNaN(p = +p)) return;
  if (p <= 0 || n < 2) return +valueof(values[0], 0, values);
  if (p >= 1) return +valueof(values[n - 1], n - 1, values);
  var n,
      i = (n - 1) * p,
      i0 = Math.floor(i),
      value0 = +valueof(values[i0], i0, values),
      value1 = +valueof(values[i0 + 1], i0 + 1, values);
  return value0 + (value1 - value0) * (i - i0);
}

function range(start, stop, step) {
  start = +start, stop = +stop, step = (n = arguments.length) < 2 ? (stop = start, start = 0, 1) : n < 3 ? 1 : +step;

  var i = -1,
      n = Math.max(0, Math.ceil((stop - start) / step)) | 0,
      range = new Array(n);

  while (++i < n) {
    range[i] = start + i * step;
  }

  return range;
}

function initRange(domain, range) {
  switch (arguments.length) {
    case 0: break;
    case 1: this.range(domain); break;
    default: this.range(range).domain(domain); break;
  }
  return this;
}

function initInterpolator(domain, interpolator) {
  switch (arguments.length) {
    case 0: break;
    case 1: {
      if (typeof domain === "function") this.interpolator(domain);
      else this.range(domain);
      break;
    }
    default: {
      this.domain(domain);
      if (typeof interpolator === "function") this.interpolator(interpolator);
      else this.range(interpolator);
      break;
    }
  }
  return this;
}

const implicit = Symbol("implicit");

function ordinal() {
  var index = new InternMap(),
      domain = [],
      range = [],
      unknown = implicit;

  function scale(d) {
    let i = index.get(d);
    if (i === undefined) {
      if (unknown !== implicit) return unknown;
      index.set(d, i = domain.push(d) - 1);
    }
    return range[i % range.length];
  }

  scale.domain = function(_) {
    if (!arguments.length) return domain.slice();
    domain = [], index = new InternMap();
    for (const value of _) {
      if (index.has(value)) continue;
      index.set(value, domain.push(value) - 1);
    }
    return scale;
  };

  scale.range = function(_) {
    return arguments.length ? (range = Array.from(_), scale) : range.slice();
  };

  scale.unknown = function(_) {
    return arguments.length ? (unknown = _, scale) : unknown;
  };

  scale.copy = function() {
    return ordinal(domain, range).unknown(unknown);
  };

  initRange.apply(scale, arguments);

  return scale;
}

function band() {
  var scale = ordinal().unknown(undefined),
      domain = scale.domain,
      ordinalRange = scale.range,
      r0 = 0,
      r1 = 1,
      step,
      bandwidth,
      round = false,
      paddingInner = 0,
      paddingOuter = 0,
      align = 0.5;

  delete scale.unknown;

  function rescale() {
    var n = domain().length,
        reverse = r1 < r0,
        start = reverse ? r1 : r0,
        stop = reverse ? r0 : r1;
    step = (stop - start) / Math.max(1, n - paddingInner + paddingOuter * 2);
    if (round) step = Math.floor(step);
    start += (stop - start - step * (n - paddingInner)) * align;
    bandwidth = step * (1 - paddingInner);
    if (round) start = Math.round(start), bandwidth = Math.round(bandwidth);
    var values = range(n).map(function(i) { return start + step * i; });
    return ordinalRange(reverse ? values.reverse() : values);
  }

  scale.domain = function(_) {
    return arguments.length ? (domain(_), rescale()) : domain();
  };

  scale.range = function(_) {
    return arguments.length ? ([r0, r1] = _, r0 = +r0, r1 = +r1, rescale()) : [r0, r1];
  };

  scale.rangeRound = function(_) {
    return [r0, r1] = _, r0 = +r0, r1 = +r1, round = true, rescale();
  };

  scale.bandwidth = function() {
    return bandwidth;
  };

  scale.step = function() {
    return step;
  };

  scale.round = function(_) {
    return arguments.length ? (round = !!_, rescale()) : round;
  };

  scale.padding = function(_) {
    return arguments.length ? (paddingInner = Math.min(1, paddingOuter = +_), rescale()) : paddingInner;
  };

  scale.paddingInner = function(_) {
    return arguments.length ? (paddingInner = Math.min(1, _), rescale()) : paddingInner;
  };

  scale.paddingOuter = function(_) {
    return arguments.length ? (paddingOuter = +_, rescale()) : paddingOuter;
  };

  scale.align = function(_) {
    return arguments.length ? (align = Math.max(0, Math.min(1, _)), rescale()) : align;
  };

  scale.copy = function() {
    return band(domain(), [r0, r1])
        .round(round)
        .paddingInner(paddingInner)
        .paddingOuter(paddingOuter)
        .align(align);
  };

  return initRange.apply(rescale(), arguments);
}

function pointish(scale) {
  var copy = scale.copy;

  scale.padding = scale.paddingOuter;
  delete scale.paddingInner;
  delete scale.paddingOuter;

  scale.copy = function() {
    return pointish(copy());
  };

  return scale;
}

function point() {
  return pointish(band.apply(null, arguments).paddingInner(1));
}

var constant$1 = x => () => x;

function linear$1(a, d) {
  return function(t) {
    return a + t * d;
  };
}

function exponential(a, b, y) {
  return a = Math.pow(a, y), b = Math.pow(b, y) - a, y = 1 / y, function(t) {
    return Math.pow(a + t * b, y);
  };
}

function gamma(y) {
  return (y = +y) === 1 ? nogamma : function(a, b) {
    return b - a ? exponential(a, b, y) : constant$1(isNaN(a) ? b : a);
  };
}

function nogamma(a, b) {
  var d = b - a;
  return d ? linear$1(a, d) : constant$1(isNaN(a) ? b : a);
}

var interpolateRgb = (function rgbGamma(y) {
  var color = gamma(y);

  function rgb$1(start, end) {
    var r = color((start = rgb(start)).r, (end = rgb(end)).r),
        g = color(start.g, end.g),
        b = color(start.b, end.b),
        opacity = nogamma(start.opacity, end.opacity);
    return function(t) {
      start.r = r(t);
      start.g = g(t);
      start.b = b(t);
      start.opacity = opacity(t);
      return start + "";
    };
  }

  rgb$1.gamma = rgbGamma;

  return rgb$1;
})(1);

function numberArray(a, b) {
  if (!b) b = [];
  var n = a ? Math.min(b.length, a.length) : 0,
      c = b.slice(),
      i;
  return function(t) {
    for (i = 0; i < n; ++i) c[i] = a[i] * (1 - t) + b[i] * t;
    return c;
  };
}

function isNumberArray(x) {
  return ArrayBuffer.isView(x) && !(x instanceof DataView);
}

function genericArray(a, b) {
  var nb = b ? b.length : 0,
      na = a ? Math.min(nb, a.length) : 0,
      x = new Array(na),
      c = new Array(nb),
      i;

  for (i = 0; i < na; ++i) x[i] = interpolate$1(a[i], b[i]);
  for (; i < nb; ++i) c[i] = b[i];

  return function(t) {
    for (i = 0; i < na; ++i) c[i] = x[i](t);
    return c;
  };
}

function date$1(a, b) {
  var d = new Date;
  return a = +a, b = +b, function(t) {
    return d.setTime(a * (1 - t) + b * t), d;
  };
}

function interpolateNumber(a, b) {
  return a = +a, b = +b, function(t) {
    return a * (1 - t) + b * t;
  };
}

function object(a, b) {
  var i = {},
      c = {},
      k;

  if (a === null || typeof a !== "object") a = {};
  if (b === null || typeof b !== "object") b = {};

  for (k in b) {
    if (k in a) {
      i[k] = interpolate$1(a[k], b[k]);
    } else {
      c[k] = b[k];
    }
  }

  return function(t) {
    for (k in i) c[k] = i[k](t);
    return c;
  };
}

var reA = /[-+]?(?:\d+\.?\d*|\.?\d+)(?:[eE][-+]?\d+)?/g,
    reB = new RegExp(reA.source, "g");

function zero(b) {
  return function() {
    return b;
  };
}

function one(b) {
  return function(t) {
    return b(t) + "";
  };
}

function interpolateString(a, b) {
  var bi = reA.lastIndex = reB.lastIndex = 0, // scan index for next number in b
      am, // current match in a
      bm, // current match in b
      bs, // string preceding current number in b, if any
      i = -1, // index in s
      s = [], // string constants and placeholders
      q = []; // number interpolators

  // Coerce inputs to strings.
  a = a + "", b = b + "";

  // Interpolate pairs of numbers in a & b.
  while ((am = reA.exec(a))
      && (bm = reB.exec(b))) {
    if ((bs = bm.index) > bi) { // a string precedes the next number in b
      bs = b.slice(bi, bs);
      if (s[i]) s[i] += bs; // coalesce with previous string
      else s[++i] = bs;
    }
    if ((am = am[0]) === (bm = bm[0])) { // numbers in a & b match
      if (s[i]) s[i] += bm; // coalesce with previous string
      else s[++i] = bm;
    } else { // interpolate non-matching numbers
      s[++i] = null;
      q.push({i: i, x: interpolateNumber(am, bm)});
    }
    bi = reB.lastIndex;
  }

  // Add remains of b.
  if (bi < b.length) {
    bs = b.slice(bi);
    if (s[i]) s[i] += bs; // coalesce with previous string
    else s[++i] = bs;
  }

  // Special optimization for only a single match.
  // Otherwise, interpolate each of the numbers and rejoin the string.
  return s.length < 2 ? (q[0]
      ? one(q[0].x)
      : zero(b))
      : (b = q.length, function(t) {
          for (var i = 0, o; i < b; ++i) s[(o = q[i]).i] = o.x(t);
          return s.join("");
        });
}

function interpolate$1(a, b) {
  var t = typeof b, c;
  return b == null || t === "boolean" ? constant$1(b)
      : (t === "number" ? interpolateNumber
      : t === "string" ? ((c = color(b)) ? (b = c, interpolateRgb) : interpolateString)
      : b instanceof color ? interpolateRgb
      : b instanceof Date ? date$1
      : isNumberArray(b) ? numberArray
      : Array.isArray(b) ? genericArray
      : typeof b.valueOf !== "function" && typeof b.toString !== "function" || isNaN(b) ? object
      : interpolateNumber)(a, b);
}

function interpolateRound(a, b) {
  return a = +a, b = +b, function(t) {
    return Math.round(a * (1 - t) + b * t);
  };
}

var degrees = 180 / Math.PI;

var identity$3 = {
  translateX: 0,
  translateY: 0,
  rotate: 0,
  skewX: 0,
  scaleX: 1,
  scaleY: 1
};

function decompose(a, b, c, d, e, f) {
  var scaleX, scaleY, skewX;
  if (scaleX = Math.sqrt(a * a + b * b)) a /= scaleX, b /= scaleX;
  if (skewX = a * c + b * d) c -= a * skewX, d -= b * skewX;
  if (scaleY = Math.sqrt(c * c + d * d)) c /= scaleY, d /= scaleY, skewX /= scaleY;
  if (a * d < b * c) a = -a, b = -b, skewX = -skewX, scaleX = -scaleX;
  return {
    translateX: e,
    translateY: f,
    rotate: Math.atan2(b, a) * degrees,
    skewX: Math.atan(skewX) * degrees,
    scaleX: scaleX,
    scaleY: scaleY
  };
}

var svgNode;

/* eslint-disable no-undef */
function parseCss(value) {
  const m = new (typeof DOMMatrix === "function" ? DOMMatrix : WebKitCSSMatrix)(value + "");
  return m.isIdentity ? identity$3 : decompose(m.a, m.b, m.c, m.d, m.e, m.f);
}

function parseSvg(value) {
  if (value == null) return identity$3;
  if (!svgNode) svgNode = document.createElementNS("http://www.w3.org/2000/svg", "g");
  svgNode.setAttribute("transform", value);
  if (!(value = svgNode.transform.baseVal.consolidate())) return identity$3;
  value = value.matrix;
  return decompose(value.a, value.b, value.c, value.d, value.e, value.f);
}

function interpolateTransform(parse, pxComma, pxParen, degParen) {

  function pop(s) {
    return s.length ? s.pop() + " " : "";
  }

  function translate(xa, ya, xb, yb, s, q) {
    if (xa !== xb || ya !== yb) {
      var i = s.push("translate(", null, pxComma, null, pxParen);
      q.push({i: i - 4, x: interpolateNumber(xa, xb)}, {i: i - 2, x: interpolateNumber(ya, yb)});
    } else if (xb || yb) {
      s.push("translate(" + xb + pxComma + yb + pxParen);
    }
  }

  function rotate(a, b, s, q) {
    if (a !== b) {
      if (a - b > 180) b += 360; else if (b - a > 180) a += 360; // shortest path
      q.push({i: s.push(pop(s) + "rotate(", null, degParen) - 2, x: interpolateNumber(a, b)});
    } else if (b) {
      s.push(pop(s) + "rotate(" + b + degParen);
    }
  }

  function skewX(a, b, s, q) {
    if (a !== b) {
      q.push({i: s.push(pop(s) + "skewX(", null, degParen) - 2, x: interpolateNumber(a, b)});
    } else if (b) {
      s.push(pop(s) + "skewX(" + b + degParen);
    }
  }

  function scale(xa, ya, xb, yb, s, q) {
    if (xa !== xb || ya !== yb) {
      var i = s.push(pop(s) + "scale(", null, ",", null, ")");
      q.push({i: i - 4, x: interpolateNumber(xa, xb)}, {i: i - 2, x: interpolateNumber(ya, yb)});
    } else if (xb !== 1 || yb !== 1) {
      s.push(pop(s) + "scale(" + xb + "," + yb + ")");
    }
  }

  return function(a, b) {
    var s = [], // string constants and placeholders
        q = []; // number interpolators
    a = parse(a), b = parse(b);
    translate(a.translateX, a.translateY, b.translateX, b.translateY, s, q);
    rotate(a.rotate, b.rotate, s, q);
    skewX(a.skewX, b.skewX, s, q);
    scale(a.scaleX, a.scaleY, b.scaleX, b.scaleY, s, q);
    a = b = null; // gc
    return function(t) {
      var i = -1, n = q.length, o;
      while (++i < n) s[(o = q[i]).i] = o.x(t);
      return s.join("");
    };
  };
}

var interpolateTransformCss = interpolateTransform(parseCss, "px, ", "px)", "deg)");
var interpolateTransformSvg = interpolateTransform(parseSvg, ", ", ")", ")");

function piecewise(interpolate, values) {
  if (values === undefined) values = interpolate, interpolate = interpolate$1;
  var i = 0, n = values.length - 1, v = values[0], I = new Array(n < 0 ? 0 : n);
  while (i < n) I[i] = interpolate(v, v = values[++i]);
  return function(t) {
    var i = Math.max(0, Math.min(n - 1, Math.floor(t *= n)));
    return I[i](t - i);
  };
}

function constants(x) {
  return function() {
    return x;
  };
}

function number$1(x) {
  return +x;
}

var unit = [0, 1];

function identity$2(x) {
  return x;
}

function normalize(a, b) {
  return (b -= (a = +a))
      ? function(x) { return (x - a) / b; }
      : constants(isNaN(b) ? NaN : 0.5);
}

function clamper(a, b) {
  var t;
  if (a > b) t = a, a = b, b = t;
  return function(x) { return Math.max(a, Math.min(b, x)); };
}

// normalize(a, b)(x) takes a domain value x in [a,b] and returns the corresponding parameter t in [0,1].
// interpolate(a, b)(t) takes a parameter t in [0,1] and returns the corresponding range value x in [a,b].
function bimap(domain, range, interpolate) {
  var d0 = domain[0], d1 = domain[1], r0 = range[0], r1 = range[1];
  if (d1 < d0) d0 = normalize(d1, d0), r0 = interpolate(r1, r0);
  else d0 = normalize(d0, d1), r0 = interpolate(r0, r1);
  return function(x) { return r0(d0(x)); };
}

function polymap(domain, range, interpolate) {
  var j = Math.min(domain.length, range.length) - 1,
      d = new Array(j),
      r = new Array(j),
      i = -1;

  // Reverse descending domains.
  if (domain[j] < domain[0]) {
    domain = domain.slice().reverse();
    range = range.slice().reverse();
  }

  while (++i < j) {
    d[i] = normalize(domain[i], domain[i + 1]);
    r[i] = interpolate(range[i], range[i + 1]);
  }

  return function(x) {
    var i = bisectRight(domain, x, 1, j) - 1;
    return r[i](d[i](x));
  };
}

function copy$1(source, target) {
  return target
      .domain(source.domain())
      .range(source.range())
      .interpolate(source.interpolate())
      .clamp(source.clamp())
      .unknown(source.unknown());
}

function transformer$2() {
  var domain = unit,
      range = unit,
      interpolate = interpolate$1,
      transform,
      untransform,
      unknown,
      clamp = identity$2,
      piecewise,
      output,
      input;

  function rescale() {
    var n = Math.min(domain.length, range.length);
    if (clamp !== identity$2) clamp = clamper(domain[0], domain[n - 1]);
    piecewise = n > 2 ? polymap : bimap;
    output = input = null;
    return scale;
  }

  function scale(x) {
    return x == null || isNaN(x = +x) ? unknown : (output || (output = piecewise(domain.map(transform), range, interpolate)))(transform(clamp(x)));
  }

  scale.invert = function(y) {
    return clamp(untransform((input || (input = piecewise(range, domain.map(transform), interpolateNumber)))(y)));
  };

  scale.domain = function(_) {
    return arguments.length ? (domain = Array.from(_, number$1), rescale()) : domain.slice();
  };

  scale.range = function(_) {
    return arguments.length ? (range = Array.from(_), rescale()) : range.slice();
  };

  scale.rangeRound = function(_) {
    return range = Array.from(_), interpolate = interpolateRound, rescale();
  };

  scale.clamp = function(_) {
    return arguments.length ? (clamp = _ ? true : identity$2, rescale()) : clamp !== identity$2;
  };

  scale.interpolate = function(_) {
    return arguments.length ? (interpolate = _, rescale()) : interpolate;
  };

  scale.unknown = function(_) {
    return arguments.length ? (unknown = _, scale) : unknown;
  };

  return function(t, u) {
    transform = t, untransform = u;
    return rescale();
  };
}

function continuous() {
  return transformer$2()(identity$2, identity$2);
}

function formatDecimal(x) {
  return Math.abs(x = Math.round(x)) >= 1e21
      ? x.toLocaleString("en").replace(/,/g, "")
      : x.toString(10);
}

// Computes the decimal coefficient and exponent of the specified number x with
// significant digits p, where x is positive and p is in [1, 21] or undefined.
// For example, formatDecimalParts(1.23) returns ["123", 0].
function formatDecimalParts(x, p) {
  if ((i = (x = p ? x.toExponential(p - 1) : x.toExponential()).indexOf("e")) < 0) return null; // NaN, ±Infinity
  var i, coefficient = x.slice(0, i);

  // The string returned by toExponential either has the form \d\.\d+e[-+]\d+
  // (e.g., 1.2e+3) or the form \de[-+]\d+ (e.g., 1e+3).
  return [
    coefficient.length > 1 ? coefficient[0] + coefficient.slice(2) : coefficient,
    +x.slice(i + 1)
  ];
}

function exponent(x) {
  return x = formatDecimalParts(Math.abs(x)), x ? x[1] : NaN;
}

function formatGroup(grouping, thousands) {
  return function(value, width) {
    var i = value.length,
        t = [],
        j = 0,
        g = grouping[0],
        length = 0;

    while (i > 0 && g > 0) {
      if (length + g + 1 > width) g = Math.max(1, width - length);
      t.push(value.substring(i -= g, i + g));
      if ((length += g + 1) > width) break;
      g = grouping[j = (j + 1) % grouping.length];
    }

    return t.reverse().join(thousands);
  };
}

function formatNumerals(numerals) {
  return function(value) {
    return value.replace(/[0-9]/g, function(i) {
      return numerals[+i];
    });
  };
}

// [[fill]align][sign][symbol][0][width][,][.precision][~][type]
var re = /^(?:(.)?([<>=^]))?([+\-( ])?([$#])?(0)?(\d+)?(,)?(\.\d+)?(~)?([a-z%])?$/i;

function formatSpecifier(specifier) {
  if (!(match = re.exec(specifier))) throw new Error("invalid format: " + specifier);
  var match;
  return new FormatSpecifier({
    fill: match[1],
    align: match[2],
    sign: match[3],
    symbol: match[4],
    zero: match[5],
    width: match[6],
    comma: match[7],
    precision: match[8] && match[8].slice(1),
    trim: match[9],
    type: match[10]
  });
}

formatSpecifier.prototype = FormatSpecifier.prototype; // instanceof

function FormatSpecifier(specifier) {
  this.fill = specifier.fill === undefined ? " " : specifier.fill + "";
  this.align = specifier.align === undefined ? ">" : specifier.align + "";
  this.sign = specifier.sign === undefined ? "-" : specifier.sign + "";
  this.symbol = specifier.symbol === undefined ? "" : specifier.symbol + "";
  this.zero = !!specifier.zero;
  this.width = specifier.width === undefined ? undefined : +specifier.width;
  this.comma = !!specifier.comma;
  this.precision = specifier.precision === undefined ? undefined : +specifier.precision;
  this.trim = !!specifier.trim;
  this.type = specifier.type === undefined ? "" : specifier.type + "";
}

FormatSpecifier.prototype.toString = function() {
  return this.fill
      + this.align
      + this.sign
      + this.symbol
      + (this.zero ? "0" : "")
      + (this.width === undefined ? "" : Math.max(1, this.width | 0))
      + (this.comma ? "," : "")
      + (this.precision === undefined ? "" : "." + Math.max(0, this.precision | 0))
      + (this.trim ? "~" : "")
      + this.type;
};

// Trims insignificant zeros, e.g., replaces 1.2000k with 1.2k.
function formatTrim(s) {
  out: for (var n = s.length, i = 1, i0 = -1, i1; i < n; ++i) {
    switch (s[i]) {
      case ".": i0 = i1 = i; break;
      case "0": if (i0 === 0) i0 = i; i1 = i; break;
      default: if (!+s[i]) break out; if (i0 > 0) i0 = 0; break;
    }
  }
  return i0 > 0 ? s.slice(0, i0) + s.slice(i1 + 1) : s;
}

var prefixExponent;

function formatPrefixAuto(x, p) {
  var d = formatDecimalParts(x, p);
  if (!d) return x + "";
  var coefficient = d[0],
      exponent = d[1],
      i = exponent - (prefixExponent = Math.max(-8, Math.min(8, Math.floor(exponent / 3))) * 3) + 1,
      n = coefficient.length;
  return i === n ? coefficient
      : i > n ? coefficient + new Array(i - n + 1).join("0")
      : i > 0 ? coefficient.slice(0, i) + "." + coefficient.slice(i)
      : "0." + new Array(1 - i).join("0") + formatDecimalParts(x, Math.max(0, p + i - 1))[0]; // less than 1y!
}

function formatRounded(x, p) {
  var d = formatDecimalParts(x, p);
  if (!d) return x + "";
  var coefficient = d[0],
      exponent = d[1];
  return exponent < 0 ? "0." + new Array(-exponent).join("0") + coefficient
      : coefficient.length > exponent + 1 ? coefficient.slice(0, exponent + 1) + "." + coefficient.slice(exponent + 1)
      : coefficient + new Array(exponent - coefficient.length + 2).join("0");
}

var formatTypes = {
  "%": (x, p) => (x * 100).toFixed(p),
  "b": (x) => Math.round(x).toString(2),
  "c": (x) => x + "",
  "d": formatDecimal,
  "e": (x, p) => x.toExponential(p),
  "f": (x, p) => x.toFixed(p),
  "g": (x, p) => x.toPrecision(p),
  "o": (x) => Math.round(x).toString(8),
  "p": (x, p) => formatRounded(x * 100, p),
  "r": formatRounded,
  "s": formatPrefixAuto,
  "X": (x) => Math.round(x).toString(16).toUpperCase(),
  "x": (x) => Math.round(x).toString(16)
};

function identity$1(x) {
  return x;
}

var map = Array.prototype.map,
    prefixes = ["y","z","a","f","p","n","µ","m","","k","M","G","T","P","E","Z","Y"];

function formatLocale$1(locale) {
  var group = locale.grouping === undefined || locale.thousands === undefined ? identity$1 : formatGroup(map.call(locale.grouping, Number), locale.thousands + ""),
      currencyPrefix = locale.currency === undefined ? "" : locale.currency[0] + "",
      currencySuffix = locale.currency === undefined ? "" : locale.currency[1] + "",
      decimal = locale.decimal === undefined ? "." : locale.decimal + "",
      numerals = locale.numerals === undefined ? identity$1 : formatNumerals(map.call(locale.numerals, String)),
      percent = locale.percent === undefined ? "%" : locale.percent + "",
      minus = locale.minus === undefined ? "−" : locale.minus + "",
      nan = locale.nan === undefined ? "NaN" : locale.nan + "";

  function newFormat(specifier) {
    specifier = formatSpecifier(specifier);

    var fill = specifier.fill,
        align = specifier.align,
        sign = specifier.sign,
        symbol = specifier.symbol,
        zero = specifier.zero,
        width = specifier.width,
        comma = specifier.comma,
        precision = specifier.precision,
        trim = specifier.trim,
        type = specifier.type;

    // The "n" type is an alias for ",g".
    if (type === "n") comma = true, type = "g";

    // The "" type, and any invalid type, is an alias for ".12~g".
    else if (!formatTypes[type]) precision === undefined && (precision = 12), trim = true, type = "g";

    // If zero fill is specified, padding goes after sign and before digits.
    if (zero || (fill === "0" && align === "=")) zero = true, fill = "0", align = "=";

    // Compute the prefix and suffix.
    // For SI-prefix, the suffix is lazily computed.
    var prefix = symbol === "$" ? currencyPrefix : symbol === "#" && /[boxX]/.test(type) ? "0" + type.toLowerCase() : "",
        suffix = symbol === "$" ? currencySuffix : /[%p]/.test(type) ? percent : "";

    // What format function should we use?
    // Is this an integer type?
    // Can this type generate exponential notation?
    var formatType = formatTypes[type],
        maybeSuffix = /[defgprs%]/.test(type);

    // Set the default precision if not specified,
    // or clamp the specified precision to the supported range.
    // For significant precision, it must be in [1, 21].
    // For fixed precision, it must be in [0, 20].
    precision = precision === undefined ? 6
        : /[gprs]/.test(type) ? Math.max(1, Math.min(21, precision))
        : Math.max(0, Math.min(20, precision));

    function format(value) {
      var valuePrefix = prefix,
          valueSuffix = suffix,
          i, n, c;

      if (type === "c") {
        valueSuffix = formatType(value) + valueSuffix;
        value = "";
      } else {
        value = +value;

        // Determine the sign. -0 is not less than 0, but 1 / -0 is!
        var valueNegative = value < 0 || 1 / value < 0;

        // Perform the initial formatting.
        value = isNaN(value) ? nan : formatType(Math.abs(value), precision);

        // Trim insignificant zeros.
        if (trim) value = formatTrim(value);

        // If a negative value rounds to zero after formatting, and no explicit positive sign is requested, hide the sign.
        if (valueNegative && +value === 0 && sign !== "+") valueNegative = false;

        // Compute the prefix and suffix.
        valuePrefix = (valueNegative ? (sign === "(" ? sign : minus) : sign === "-" || sign === "(" ? "" : sign) + valuePrefix;
        valueSuffix = (type === "s" ? prefixes[8 + prefixExponent / 3] : "") + valueSuffix + (valueNegative && sign === "(" ? ")" : "");

        // Break the formatted value into the integer “value” part that can be
        // grouped, and fractional or exponential “suffix” part that is not.
        if (maybeSuffix) {
          i = -1, n = value.length;
          while (++i < n) {
            if (c = value.charCodeAt(i), 48 > c || c > 57) {
              valueSuffix = (c === 46 ? decimal + value.slice(i + 1) : value.slice(i)) + valueSuffix;
              value = value.slice(0, i);
              break;
            }
          }
        }
      }

      // If the fill character is not "0", grouping is applied before padding.
      if (comma && !zero) value = group(value, Infinity);

      // Compute the padding.
      var length = valuePrefix.length + value.length + valueSuffix.length,
          padding = length < width ? new Array(width - length + 1).join(fill) : "";

      // If the fill character is "0", grouping is applied after padding.
      if (comma && zero) value = group(padding + value, padding.length ? width - valueSuffix.length : Infinity), padding = "";

      // Reconstruct the final output based on the desired alignment.
      switch (align) {
        case "<": value = valuePrefix + value + valueSuffix + padding; break;
        case "=": value = valuePrefix + padding + value + valueSuffix; break;
        case "^": value = padding.slice(0, length = padding.length >> 1) + valuePrefix + value + valueSuffix + padding.slice(length); break;
        default: value = padding + valuePrefix + value + valueSuffix; break;
      }

      return numerals(value);
    }

    format.toString = function() {
      return specifier + "";
    };

    return format;
  }

  function formatPrefix(specifier, value) {
    var f = newFormat((specifier = formatSpecifier(specifier), specifier.type = "f", specifier)),
        e = Math.max(-8, Math.min(8, Math.floor(exponent(value) / 3))) * 3,
        k = Math.pow(10, -e),
        prefix = prefixes[8 + e / 3];
    return function(value) {
      return f(k * value) + prefix;
    };
  }

  return {
    format: newFormat,
    formatPrefix: formatPrefix
  };
}

var locale$1;
var format;
var formatPrefix;

defaultLocale$1({
  thousands: ",",
  grouping: [3],
  currency: ["$", ""]
});

function defaultLocale$1(definition) {
  locale$1 = formatLocale$1(definition);
  format = locale$1.format;
  formatPrefix = locale$1.formatPrefix;
  return locale$1;
}

function precisionFixed(step) {
  return Math.max(0, -exponent(Math.abs(step)));
}

function precisionPrefix(step, value) {
  return Math.max(0, Math.max(-8, Math.min(8, Math.floor(exponent(value) / 3))) * 3 - exponent(Math.abs(step)));
}

function precisionRound(step, max) {
  step = Math.abs(step), max = Math.abs(max) - step;
  return Math.max(0, exponent(max) - exponent(step)) + 1;
}

function tickFormat(start, stop, count, specifier) {
  var step = tickStep(start, stop, count),
      precision;
  specifier = formatSpecifier(specifier == null ? ",f" : specifier);
  switch (specifier.type) {
    case "s": {
      var value = Math.max(Math.abs(start), Math.abs(stop));
      if (specifier.precision == null && !isNaN(precision = precisionPrefix(step, value))) specifier.precision = precision;
      return formatPrefix(specifier, value);
    }
    case "":
    case "e":
    case "g":
    case "p":
    case "r": {
      if (specifier.precision == null && !isNaN(precision = precisionRound(step, Math.max(Math.abs(start), Math.abs(stop))))) specifier.precision = precision - (specifier.type === "e");
      break;
    }
    case "f":
    case "%": {
      if (specifier.precision == null && !isNaN(precision = precisionFixed(step))) specifier.precision = precision - (specifier.type === "%") * 2;
      break;
    }
  }
  return format(specifier);
}

function linearish(scale) {
  var domain = scale.domain;

  scale.ticks = function(count) {
    var d = domain();
    return ticks(d[0], d[d.length - 1], count == null ? 10 : count);
  };

  scale.tickFormat = function(count, specifier) {
    var d = domain();
    return tickFormat(d[0], d[d.length - 1], count == null ? 10 : count, specifier);
  };

  scale.nice = function(count) {
    if (count == null) count = 10;

    var d = domain();
    var i0 = 0;
    var i1 = d.length - 1;
    var start = d[i0];
    var stop = d[i1];
    var prestep;
    var step;
    var maxIter = 10;

    if (stop < start) {
      step = start, start = stop, stop = step;
      step = i0, i0 = i1, i1 = step;
    }
    
    while (maxIter-- > 0) {
      step = tickIncrement(start, stop, count);
      if (step === prestep) {
        d[i0] = start;
        d[i1] = stop;
        return domain(d);
      } else if (step > 0) {
        start = Math.floor(start / step) * step;
        stop = Math.ceil(stop / step) * step;
      } else if (step < 0) {
        start = Math.ceil(start * step) / step;
        stop = Math.floor(stop * step) / step;
      } else {
        break;
      }
      prestep = step;
    }

    return scale;
  };

  return scale;
}

function linear() {
  var scale = continuous();

  scale.copy = function() {
    return copy$1(scale, linear());
  };

  initRange.apply(scale, arguments);

  return linearish(scale);
}

function identity(domain) {
  var unknown;

  function scale(x) {
    return x == null || isNaN(x = +x) ? unknown : x;
  }

  scale.invert = scale;

  scale.domain = scale.range = function(_) {
    return arguments.length ? (domain = Array.from(_, number$1), scale) : domain.slice();
  };

  scale.unknown = function(_) {
    return arguments.length ? (unknown = _, scale) : unknown;
  };

  scale.copy = function() {
    return identity(domain).unknown(unknown);
  };

  domain = arguments.length ? Array.from(domain, number$1) : [0, 1];

  return linearish(scale);
}

function nice(domain, interval) {
  domain = domain.slice();

  var i0 = 0,
      i1 = domain.length - 1,
      x0 = domain[i0],
      x1 = domain[i1],
      t;

  if (x1 < x0) {
    t = i0, i0 = i1, i1 = t;
    t = x0, x0 = x1, x1 = t;
  }

  domain[i0] = interval.floor(x0);
  domain[i1] = interval.ceil(x1);
  return domain;
}

function transformLog(x) {
  return Math.log(x);
}

function transformExp(x) {
  return Math.exp(x);
}

function transformLogn(x) {
  return -Math.log(-x);
}

function transformExpn(x) {
  return -Math.exp(-x);
}

function pow10(x) {
  return isFinite(x) ? +("1e" + x) : x < 0 ? 0 : x;
}

function powp(base) {
  return base === 10 ? pow10
      : base === Math.E ? Math.exp
      : x => Math.pow(base, x);
}

function logp(base) {
  return base === Math.E ? Math.log
      : base === 10 && Math.log10
      || base === 2 && Math.log2
      || (base = Math.log(base), x => Math.log(x) / base);
}

function reflect(f) {
  return (x, k) => -f(-x, k);
}

function loggish(transform) {
  const scale = transform(transformLog, transformExp);
  const domain = scale.domain;
  let base = 10;
  let logs;
  let pows;

  function rescale() {
    logs = logp(base), pows = powp(base);
    if (domain()[0] < 0) {
      logs = reflect(logs), pows = reflect(pows);
      transform(transformLogn, transformExpn);
    } else {
      transform(transformLog, transformExp);
    }
    return scale;
  }

  scale.base = function(_) {
    return arguments.length ? (base = +_, rescale()) : base;
  };

  scale.domain = function(_) {
    return arguments.length ? (domain(_), rescale()) : domain();
  };

  scale.ticks = count => {
    const d = domain();
    let u = d[0];
    let v = d[d.length - 1];
    const r = v < u;

    if (r) ([u, v] = [v, u]);

    let i = logs(u);
    let j = logs(v);
    let k;
    let t;
    const n = count == null ? 10 : +count;
    let z = [];

    if (!(base % 1) && j - i < n) {
      i = Math.floor(i), j = Math.ceil(j);
      if (u > 0) for (; i <= j; ++i) {
        for (k = 1; k < base; ++k) {
          t = i < 0 ? k / pows(-i) : k * pows(i);
          if (t < u) continue;
          if (t > v) break;
          z.push(t);
        }
      } else for (; i <= j; ++i) {
        for (k = base - 1; k >= 1; --k) {
          t = i > 0 ? k / pows(-i) : k * pows(i);
          if (t < u) continue;
          if (t > v) break;
          z.push(t);
        }
      }
      if (z.length * 2 < n) z = ticks(u, v, n);
    } else {
      z = ticks(i, j, Math.min(j - i, n)).map(pows);
    }
    return r ? z.reverse() : z;
  };

  scale.tickFormat = (count, specifier) => {
    if (count == null) count = 10;
    if (specifier == null) specifier = base === 10 ? "s" : ",";
    if (typeof specifier !== "function") {
      if (!(base % 1) && (specifier = formatSpecifier(specifier)).precision == null) specifier.trim = true;
      specifier = format(specifier);
    }
    if (count === Infinity) return specifier;
    const k = Math.max(1, base * count / scale.ticks().length); // TODO fast estimate?
    return d => {
      let i = d / pows(Math.round(logs(d)));
      if (i * base < base - 0.5) i *= base;
      return i <= k ? specifier(d) : "";
    };
  };

  scale.nice = () => {
    return domain(nice(domain(), {
      floor: x => pows(Math.floor(logs(x))),
      ceil: x => pows(Math.ceil(logs(x)))
    }));
  };

  return scale;
}

function log() {
  const scale = loggish(transformer$2()).domain([1, 10]);
  scale.copy = () => copy$1(scale, log()).base(scale.base());
  initRange.apply(scale, arguments);
  return scale;
}

function transformSymlog(c) {
  return function(x) {
    return Math.sign(x) * Math.log1p(Math.abs(x / c));
  };
}

function transformSymexp(c) {
  return function(x) {
    return Math.sign(x) * Math.expm1(Math.abs(x)) * c;
  };
}

function symlogish(transform) {
  var c = 1, scale = transform(transformSymlog(c), transformSymexp(c));

  scale.constant = function(_) {
    return arguments.length ? transform(transformSymlog(c = +_), transformSymexp(c)) : c;
  };

  return linearish(scale);
}

function symlog() {
  var scale = symlogish(transformer$2());

  scale.copy = function() {
    return copy$1(scale, symlog()).constant(scale.constant());
  };

  return initRange.apply(scale, arguments);
}

function transformPow(exponent) {
  return function(x) {
    return x < 0 ? -Math.pow(-x, exponent) : Math.pow(x, exponent);
  };
}

function transformSqrt(x) {
  return x < 0 ? -Math.sqrt(-x) : Math.sqrt(x);
}

function transformSquare(x) {
  return x < 0 ? -x * x : x * x;
}

function powish(transform) {
  var scale = transform(identity$2, identity$2),
      exponent = 1;

  function rescale() {
    return exponent === 1 ? transform(identity$2, identity$2)
        : exponent === 0.5 ? transform(transformSqrt, transformSquare)
        : transform(transformPow(exponent), transformPow(1 / exponent));
  }

  scale.exponent = function(_) {
    return arguments.length ? (exponent = +_, rescale()) : exponent;
  };

  return linearish(scale);
}

function pow() {
  var scale = powish(transformer$2());

  scale.copy = function() {
    return copy$1(scale, pow()).exponent(scale.exponent());
  };

  initRange.apply(scale, arguments);

  return scale;
}

function sqrt$1() {
  return pow.apply(null, arguments).exponent(0.5);
}

function square(x) {
  return Math.sign(x) * x * x;
}

function unsquare(x) {
  return Math.sign(x) * Math.sqrt(Math.abs(x));
}

function radial() {
  var squared = continuous(),
      range = [0, 1],
      round = false,
      unknown;

  function scale(x) {
    var y = unsquare(squared(x));
    return isNaN(y) ? unknown : round ? Math.round(y) : y;
  }

  scale.invert = function(y) {
    return squared.invert(square(y));
  };

  scale.domain = function(_) {
    return arguments.length ? (squared.domain(_), scale) : squared.domain();
  };

  scale.range = function(_) {
    return arguments.length ? (squared.range((range = Array.from(_, number$1)).map(square)), scale) : range.slice();
  };

  scale.rangeRound = function(_) {
    return scale.range(_).round(true);
  };

  scale.round = function(_) {
    return arguments.length ? (round = !!_, scale) : round;
  };

  scale.clamp = function(_) {
    return arguments.length ? (squared.clamp(_), scale) : squared.clamp();
  };

  scale.unknown = function(_) {
    return arguments.length ? (unknown = _, scale) : unknown;
  };

  scale.copy = function() {
    return radial(squared.domain(), range)
        .round(round)
        .clamp(squared.clamp())
        .unknown(unknown);
  };

  initRange.apply(scale, arguments);

  return linearish(scale);
}

function quantile() {
  var domain = [],
      range = [],
      thresholds = [],
      unknown;

  function rescale() {
    var i = 0, n = Math.max(1, range.length);
    thresholds = new Array(n - 1);
    while (++i < n) thresholds[i - 1] = quantileSorted(domain, i / n);
    return scale;
  }

  function scale(x) {
    return x == null || isNaN(x = +x) ? unknown : range[bisectRight(thresholds, x)];
  }

  scale.invertExtent = function(y) {
    var i = range.indexOf(y);
    return i < 0 ? [NaN, NaN] : [
      i > 0 ? thresholds[i - 1] : domain[0],
      i < thresholds.length ? thresholds[i] : domain[domain.length - 1]
    ];
  };

  scale.domain = function(_) {
    if (!arguments.length) return domain.slice();
    domain = [];
    for (let d of _) if (d != null && !isNaN(d = +d)) domain.push(d);
    domain.sort(ascending);
    return rescale();
  };

  scale.range = function(_) {
    return arguments.length ? (range = Array.from(_), rescale()) : range.slice();
  };

  scale.unknown = function(_) {
    return arguments.length ? (unknown = _, scale) : unknown;
  };

  scale.quantiles = function() {
    return thresholds.slice();
  };

  scale.copy = function() {
    return quantile()
        .domain(domain)
        .range(range)
        .unknown(unknown);
  };

  return initRange.apply(scale, arguments);
}

function quantize() {
  var x0 = 0,
      x1 = 1,
      n = 1,
      domain = [0.5],
      range = [0, 1],
      unknown;

  function scale(x) {
    return x != null && x <= x ? range[bisectRight(domain, x, 0, n)] : unknown;
  }

  function rescale() {
    var i = -1;
    domain = new Array(n);
    while (++i < n) domain[i] = ((i + 1) * x1 - (i - n) * x0) / (n + 1);
    return scale;
  }

  scale.domain = function(_) {
    return arguments.length ? ([x0, x1] = _, x0 = +x0, x1 = +x1, rescale()) : [x0, x1];
  };

  scale.range = function(_) {
    return arguments.length ? (n = (range = Array.from(_)).length - 1, rescale()) : range.slice();
  };

  scale.invertExtent = function(y) {
    var i = range.indexOf(y);
    return i < 0 ? [NaN, NaN]
        : i < 1 ? [x0, domain[0]]
        : i >= n ? [domain[n - 1], x1]
        : [domain[i - 1], domain[i]];
  };

  scale.unknown = function(_) {
    return arguments.length ? (unknown = _, scale) : scale;
  };

  scale.thresholds = function() {
    return domain.slice();
  };

  scale.copy = function() {
    return quantize()
        .domain([x0, x1])
        .range(range)
        .unknown(unknown);
  };

  return initRange.apply(linearish(scale), arguments);
}

function threshold() {
  var domain = [0.5],
      range = [0, 1],
      unknown,
      n = 1;

  function scale(x) {
    return x != null && x <= x ? range[bisectRight(domain, x, 0, n)] : unknown;
  }

  scale.domain = function(_) {
    return arguments.length ? (domain = Array.from(_), n = Math.min(domain.length, range.length - 1), scale) : domain.slice();
  };

  scale.range = function(_) {
    return arguments.length ? (range = Array.from(_), n = Math.min(domain.length, range.length - 1), scale) : range.slice();
  };

  scale.invertExtent = function(y) {
    var i = range.indexOf(y);
    return [domain[i - 1], domain[i]];
  };

  scale.unknown = function(_) {
    return arguments.length ? (unknown = _, scale) : unknown;
  };

  scale.copy = function() {
    return threshold()
        .domain(domain)
        .range(range)
        .unknown(unknown);
  };

  return initRange.apply(scale, arguments);
}

const t0 = new Date, t1 = new Date;

function timeInterval(floori, offseti, count, field) {

  function interval(date) {
    return floori(date = arguments.length === 0 ? new Date : new Date(+date)), date;
  }

  interval.floor = (date) => {
    return floori(date = new Date(+date)), date;
  };

  interval.ceil = (date) => {
    return floori(date = new Date(date - 1)), offseti(date, 1), floori(date), date;
  };

  interval.round = (date) => {
    const d0 = interval(date), d1 = interval.ceil(date);
    return date - d0 < d1 - date ? d0 : d1;
  };

  interval.offset = (date, step) => {
    return offseti(date = new Date(+date), step == null ? 1 : Math.floor(step)), date;
  };

  interval.range = (start, stop, step) => {
    const range = [];
    start = interval.ceil(start);
    step = step == null ? 1 : Math.floor(step);
    if (!(start < stop) || !(step > 0)) return range; // also handles Invalid Date
    let previous;
    do range.push(previous = new Date(+start)), offseti(start, step), floori(start);
    while (previous < start && start < stop);
    return range;
  };

  interval.filter = (test) => {
    return timeInterval((date) => {
      if (date >= date) while (floori(date), !test(date)) date.setTime(date - 1);
    }, (date, step) => {
      if (date >= date) {
        if (step < 0) while (++step <= 0) {
          while (offseti(date, -1), !test(date)) {} // eslint-disable-line no-empty
        } else while (--step >= 0) {
          while (offseti(date, 1), !test(date)) {} // eslint-disable-line no-empty
        }
      }
    });
  };

  if (count) {
    interval.count = (start, end) => {
      t0.setTime(+start), t1.setTime(+end);
      floori(t0), floori(t1);
      return Math.floor(count(t0, t1));
    };

    interval.every = (step) => {
      step = Math.floor(step);
      return !isFinite(step) || !(step > 0) ? null
          : !(step > 1) ? interval
          : interval.filter(field
              ? (d) => field(d) % step === 0
              : (d) => interval.count(0, d) % step === 0);
    };
  }

  return interval;
}

const millisecond = timeInterval(() => {
  // noop
}, (date, step) => {
  date.setTime(+date + step);
}, (start, end) => {
  return end - start;
});

// An optimized implementation for this simple case.
millisecond.every = (k) => {
  k = Math.floor(k);
  if (!isFinite(k) || !(k > 0)) return null;
  if (!(k > 1)) return millisecond;
  return timeInterval((date) => {
    date.setTime(Math.floor(date / k) * k);
  }, (date, step) => {
    date.setTime(+date + step * k);
  }, (start, end) => {
    return (end - start) / k;
  });
};

millisecond.range;

const durationSecond = 1000;
const durationMinute = durationSecond * 60;
const durationHour = durationMinute * 60;
const durationDay = durationHour * 24;
const durationWeek = durationDay * 7;
const durationMonth = durationDay * 30;
const durationYear = durationDay * 365;

const second = timeInterval((date) => {
  date.setTime(date - date.getMilliseconds());
}, (date, step) => {
  date.setTime(+date + step * durationSecond);
}, (start, end) => {
  return (end - start) / durationSecond;
}, (date) => {
  return date.getUTCSeconds();
});

second.range;

const timeMinute = timeInterval((date) => {
  date.setTime(date - date.getMilliseconds() - date.getSeconds() * durationSecond);
}, (date, step) => {
  date.setTime(+date + step * durationMinute);
}, (start, end) => {
  return (end - start) / durationMinute;
}, (date) => {
  return date.getMinutes();
});

timeMinute.range;

const utcMinute = timeInterval((date) => {
  date.setUTCSeconds(0, 0);
}, (date, step) => {
  date.setTime(+date + step * durationMinute);
}, (start, end) => {
  return (end - start) / durationMinute;
}, (date) => {
  return date.getUTCMinutes();
});

utcMinute.range;

const timeHour = timeInterval((date) => {
  date.setTime(date - date.getMilliseconds() - date.getSeconds() * durationSecond - date.getMinutes() * durationMinute);
}, (date, step) => {
  date.setTime(+date + step * durationHour);
}, (start, end) => {
  return (end - start) / durationHour;
}, (date) => {
  return date.getHours();
});

timeHour.range;

const utcHour = timeInterval((date) => {
  date.setUTCMinutes(0, 0, 0);
}, (date, step) => {
  date.setTime(+date + step * durationHour);
}, (start, end) => {
  return (end - start) / durationHour;
}, (date) => {
  return date.getUTCHours();
});

utcHour.range;

const timeDay = timeInterval(
  date => date.setHours(0, 0, 0, 0),
  (date, step) => date.setDate(date.getDate() + step),
  (start, end) => (end - start - (end.getTimezoneOffset() - start.getTimezoneOffset()) * durationMinute) / durationDay,
  date => date.getDate() - 1
);

timeDay.range;

const utcDay = timeInterval((date) => {
  date.setUTCHours(0, 0, 0, 0);
}, (date, step) => {
  date.setUTCDate(date.getUTCDate() + step);
}, (start, end) => {
  return (end - start) / durationDay;
}, (date) => {
  return date.getUTCDate() - 1;
});

utcDay.range;

const unixDay = timeInterval((date) => {
  date.setUTCHours(0, 0, 0, 0);
}, (date, step) => {
  date.setUTCDate(date.getUTCDate() + step);
}, (start, end) => {
  return (end - start) / durationDay;
}, (date) => {
  return Math.floor(date / durationDay);
});

unixDay.range;

function timeWeekday(i) {
  return timeInterval((date) => {
    date.setDate(date.getDate() - (date.getDay() + 7 - i) % 7);
    date.setHours(0, 0, 0, 0);
  }, (date, step) => {
    date.setDate(date.getDate() + step * 7);
  }, (start, end) => {
    return (end - start - (end.getTimezoneOffset() - start.getTimezoneOffset()) * durationMinute) / durationWeek;
  });
}

const timeSunday = timeWeekday(0);
const timeMonday = timeWeekday(1);
const timeTuesday = timeWeekday(2);
const timeWednesday = timeWeekday(3);
const timeThursday = timeWeekday(4);
const timeFriday = timeWeekday(5);
const timeSaturday = timeWeekday(6);

timeSunday.range;
timeMonday.range;
timeTuesday.range;
timeWednesday.range;
timeThursday.range;
timeFriday.range;
timeSaturday.range;

function utcWeekday(i) {
  return timeInterval((date) => {
    date.setUTCDate(date.getUTCDate() - (date.getUTCDay() + 7 - i) % 7);
    date.setUTCHours(0, 0, 0, 0);
  }, (date, step) => {
    date.setUTCDate(date.getUTCDate() + step * 7);
  }, (start, end) => {
    return (end - start) / durationWeek;
  });
}

const utcSunday = utcWeekday(0);
const utcMonday = utcWeekday(1);
const utcTuesday = utcWeekday(2);
const utcWednesday = utcWeekday(3);
const utcThursday = utcWeekday(4);
const utcFriday = utcWeekday(5);
const utcSaturday = utcWeekday(6);

utcSunday.range;
utcMonday.range;
utcTuesday.range;
utcWednesday.range;
utcThursday.range;
utcFriday.range;
utcSaturday.range;

const timeMonth = timeInterval((date) => {
  date.setDate(1);
  date.setHours(0, 0, 0, 0);
}, (date, step) => {
  date.setMonth(date.getMonth() + step);
}, (start, end) => {
  return end.getMonth() - start.getMonth() + (end.getFullYear() - start.getFullYear()) * 12;
}, (date) => {
  return date.getMonth();
});

timeMonth.range;

const utcMonth = timeInterval((date) => {
  date.setUTCDate(1);
  date.setUTCHours(0, 0, 0, 0);
}, (date, step) => {
  date.setUTCMonth(date.getUTCMonth() + step);
}, (start, end) => {
  return end.getUTCMonth() - start.getUTCMonth() + (end.getUTCFullYear() - start.getUTCFullYear()) * 12;
}, (date) => {
  return date.getUTCMonth();
});

utcMonth.range;

const timeYear = timeInterval((date) => {
  date.setMonth(0, 1);
  date.setHours(0, 0, 0, 0);
}, (date, step) => {
  date.setFullYear(date.getFullYear() + step);
}, (start, end) => {
  return end.getFullYear() - start.getFullYear();
}, (date) => {
  return date.getFullYear();
});

// An optimized implementation for this simple case.
timeYear.every = (k) => {
  return !isFinite(k = Math.floor(k)) || !(k > 0) ? null : timeInterval((date) => {
    date.setFullYear(Math.floor(date.getFullYear() / k) * k);
    date.setMonth(0, 1);
    date.setHours(0, 0, 0, 0);
  }, (date, step) => {
    date.setFullYear(date.getFullYear() + step * k);
  });
};

timeYear.range;

const utcYear = timeInterval((date) => {
  date.setUTCMonth(0, 1);
  date.setUTCHours(0, 0, 0, 0);
}, (date, step) => {
  date.setUTCFullYear(date.getUTCFullYear() + step);
}, (start, end) => {
  return end.getUTCFullYear() - start.getUTCFullYear();
}, (date) => {
  return date.getUTCFullYear();
});

// An optimized implementation for this simple case.
utcYear.every = (k) => {
  return !isFinite(k = Math.floor(k)) || !(k > 0) ? null : timeInterval((date) => {
    date.setUTCFullYear(Math.floor(date.getUTCFullYear() / k) * k);
    date.setUTCMonth(0, 1);
    date.setUTCHours(0, 0, 0, 0);
  }, (date, step) => {
    date.setUTCFullYear(date.getUTCFullYear() + step * k);
  });
};

utcYear.range;

function ticker(year, month, week, day, hour, minute) {

  const tickIntervals = [
    [second,  1,      durationSecond],
    [second,  5,  5 * durationSecond],
    [second, 15, 15 * durationSecond],
    [second, 30, 30 * durationSecond],
    [minute,  1,      durationMinute],
    [minute,  5,  5 * durationMinute],
    [minute, 15, 15 * durationMinute],
    [minute, 30, 30 * durationMinute],
    [  hour,  1,      durationHour  ],
    [  hour,  3,  3 * durationHour  ],
    [  hour,  6,  6 * durationHour  ],
    [  hour, 12, 12 * durationHour  ],
    [   day,  1,      durationDay   ],
    [   day,  2,  2 * durationDay   ],
    [  week,  1,      durationWeek  ],
    [ month,  1,      durationMonth ],
    [ month,  3,  3 * durationMonth ],
    [  year,  1,      durationYear  ]
  ];

  function ticks(start, stop, count) {
    const reverse = stop < start;
    if (reverse) [start, stop] = [stop, start];
    const interval = count && typeof count.range === "function" ? count : tickInterval(start, stop, count);
    const ticks = interval ? interval.range(start, +stop + 1) : []; // inclusive stop
    return reverse ? ticks.reverse() : ticks;
  }

  function tickInterval(start, stop, count) {
    const target = Math.abs(stop - start) / count;
    const i = bisector(([,, step]) => step).right(tickIntervals, target);
    if (i === tickIntervals.length) return year.every(tickStep(start / durationYear, stop / durationYear, count));
    if (i === 0) return millisecond.every(Math.max(tickStep(start, stop, count), 1));
    const [t, step] = tickIntervals[target / tickIntervals[i - 1][2] < tickIntervals[i][2] / target ? i - 1 : i];
    return t.every(step);
  }

  return [ticks, tickInterval];
}

const [utcTicks, utcTickInterval] = ticker(utcYear, utcMonth, utcSunday, unixDay, utcHour, utcMinute);
const [timeTicks, timeTickInterval] = ticker(timeYear, timeMonth, timeSunday, timeDay, timeHour, timeMinute);

function localDate(d) {
  if (0 <= d.y && d.y < 100) {
    var date = new Date(-1, d.m, d.d, d.H, d.M, d.S, d.L);
    date.setFullYear(d.y);
    return date;
  }
  return new Date(d.y, d.m, d.d, d.H, d.M, d.S, d.L);
}

function utcDate(d) {
  if (0 <= d.y && d.y < 100) {
    var date = new Date(Date.UTC(-1, d.m, d.d, d.H, d.M, d.S, d.L));
    date.setUTCFullYear(d.y);
    return date;
  }
  return new Date(Date.UTC(d.y, d.m, d.d, d.H, d.M, d.S, d.L));
}

function newDate(y, m, d) {
  return {y: y, m: m, d: d, H: 0, M: 0, S: 0, L: 0};
}

function formatLocale(locale) {
  var locale_dateTime = locale.dateTime,
      locale_date = locale.date,
      locale_time = locale.time,
      locale_periods = locale.periods,
      locale_weekdays = locale.days,
      locale_shortWeekdays = locale.shortDays,
      locale_months = locale.months,
      locale_shortMonths = locale.shortMonths;

  var periodRe = formatRe(locale_periods),
      periodLookup = formatLookup(locale_periods),
      weekdayRe = formatRe(locale_weekdays),
      weekdayLookup = formatLookup(locale_weekdays),
      shortWeekdayRe = formatRe(locale_shortWeekdays),
      shortWeekdayLookup = formatLookup(locale_shortWeekdays),
      monthRe = formatRe(locale_months),
      monthLookup = formatLookup(locale_months),
      shortMonthRe = formatRe(locale_shortMonths),
      shortMonthLookup = formatLookup(locale_shortMonths);

  var formats = {
    "a": formatShortWeekday,
    "A": formatWeekday,
    "b": formatShortMonth,
    "B": formatMonth,
    "c": null,
    "d": formatDayOfMonth,
    "e": formatDayOfMonth,
    "f": formatMicroseconds,
    "g": formatYearISO,
    "G": formatFullYearISO,
    "H": formatHour24,
    "I": formatHour12,
    "j": formatDayOfYear,
    "L": formatMilliseconds,
    "m": formatMonthNumber,
    "M": formatMinutes,
    "p": formatPeriod,
    "q": formatQuarter,
    "Q": formatUnixTimestamp,
    "s": formatUnixTimestampSeconds,
    "S": formatSeconds,
    "u": formatWeekdayNumberMonday,
    "U": formatWeekNumberSunday,
    "V": formatWeekNumberISO,
    "w": formatWeekdayNumberSunday,
    "W": formatWeekNumberMonday,
    "x": null,
    "X": null,
    "y": formatYear,
    "Y": formatFullYear,
    "Z": formatZone,
    "%": formatLiteralPercent
  };

  var utcFormats = {
    "a": formatUTCShortWeekday,
    "A": formatUTCWeekday,
    "b": formatUTCShortMonth,
    "B": formatUTCMonth,
    "c": null,
    "d": formatUTCDayOfMonth,
    "e": formatUTCDayOfMonth,
    "f": formatUTCMicroseconds,
    "g": formatUTCYearISO,
    "G": formatUTCFullYearISO,
    "H": formatUTCHour24,
    "I": formatUTCHour12,
    "j": formatUTCDayOfYear,
    "L": formatUTCMilliseconds,
    "m": formatUTCMonthNumber,
    "M": formatUTCMinutes,
    "p": formatUTCPeriod,
    "q": formatUTCQuarter,
    "Q": formatUnixTimestamp,
    "s": formatUnixTimestampSeconds,
    "S": formatUTCSeconds,
    "u": formatUTCWeekdayNumberMonday,
    "U": formatUTCWeekNumberSunday,
    "V": formatUTCWeekNumberISO,
    "w": formatUTCWeekdayNumberSunday,
    "W": formatUTCWeekNumberMonday,
    "x": null,
    "X": null,
    "y": formatUTCYear,
    "Y": formatUTCFullYear,
    "Z": formatUTCZone,
    "%": formatLiteralPercent
  };

  var parses = {
    "a": parseShortWeekday,
    "A": parseWeekday,
    "b": parseShortMonth,
    "B": parseMonth,
    "c": parseLocaleDateTime,
    "d": parseDayOfMonth,
    "e": parseDayOfMonth,
    "f": parseMicroseconds,
    "g": parseYear,
    "G": parseFullYear,
    "H": parseHour24,
    "I": parseHour24,
    "j": parseDayOfYear,
    "L": parseMilliseconds,
    "m": parseMonthNumber,
    "M": parseMinutes,
    "p": parsePeriod,
    "q": parseQuarter,
    "Q": parseUnixTimestamp,
    "s": parseUnixTimestampSeconds,
    "S": parseSeconds,
    "u": parseWeekdayNumberMonday,
    "U": parseWeekNumberSunday,
    "V": parseWeekNumberISO,
    "w": parseWeekdayNumberSunday,
    "W": parseWeekNumberMonday,
    "x": parseLocaleDate,
    "X": parseLocaleTime,
    "y": parseYear,
    "Y": parseFullYear,
    "Z": parseZone,
    "%": parseLiteralPercent
  };

  // These recursive directive definitions must be deferred.
  formats.x = newFormat(locale_date, formats);
  formats.X = newFormat(locale_time, formats);
  formats.c = newFormat(locale_dateTime, formats);
  utcFormats.x = newFormat(locale_date, utcFormats);
  utcFormats.X = newFormat(locale_time, utcFormats);
  utcFormats.c = newFormat(locale_dateTime, utcFormats);

  function newFormat(specifier, formats) {
    return function(date) {
      var string = [],
          i = -1,
          j = 0,
          n = specifier.length,
          c,
          pad,
          format;

      if (!(date instanceof Date)) date = new Date(+date);

      while (++i < n) {
        if (specifier.charCodeAt(i) === 37) {
          string.push(specifier.slice(j, i));
          if ((pad = pads[c = specifier.charAt(++i)]) != null) c = specifier.charAt(++i);
          else pad = c === "e" ? " " : "0";
          if (format = formats[c]) c = format(date, pad);
          string.push(c);
          j = i + 1;
        }
      }

      string.push(specifier.slice(j, i));
      return string.join("");
    };
  }

  function newParse(specifier, Z) {
    return function(string) {
      var d = newDate(1900, undefined, 1),
          i = parseSpecifier(d, specifier, string += "", 0),
          week, day;
      if (i != string.length) return null;

      // If a UNIX timestamp is specified, return it.
      if ("Q" in d) return new Date(d.Q);
      if ("s" in d) return new Date(d.s * 1000 + ("L" in d ? d.L : 0));

      // If this is utcParse, never use the local timezone.
      if (Z && !("Z" in d)) d.Z = 0;

      // The am-pm flag is 0 for AM, and 1 for PM.
      if ("p" in d) d.H = d.H % 12 + d.p * 12;

      // If the month was not specified, inherit from the quarter.
      if (d.m === undefined) d.m = "q" in d ? d.q : 0;

      // Convert day-of-week and week-of-year to day-of-year.
      if ("V" in d) {
        if (d.V < 1 || d.V > 53) return null;
        if (!("w" in d)) d.w = 1;
        if ("Z" in d) {
          week = utcDate(newDate(d.y, 0, 1)), day = week.getUTCDay();
          week = day > 4 || day === 0 ? utcMonday.ceil(week) : utcMonday(week);
          week = utcDay.offset(week, (d.V - 1) * 7);
          d.y = week.getUTCFullYear();
          d.m = week.getUTCMonth();
          d.d = week.getUTCDate() + (d.w + 6) % 7;
        } else {
          week = localDate(newDate(d.y, 0, 1)), day = week.getDay();
          week = day > 4 || day === 0 ? timeMonday.ceil(week) : timeMonday(week);
          week = timeDay.offset(week, (d.V - 1) * 7);
          d.y = week.getFullYear();
          d.m = week.getMonth();
          d.d = week.getDate() + (d.w + 6) % 7;
        }
      } else if ("W" in d || "U" in d) {
        if (!("w" in d)) d.w = "u" in d ? d.u % 7 : "W" in d ? 1 : 0;
        day = "Z" in d ? utcDate(newDate(d.y, 0, 1)).getUTCDay() : localDate(newDate(d.y, 0, 1)).getDay();
        d.m = 0;
        d.d = "W" in d ? (d.w + 6) % 7 + d.W * 7 - (day + 5) % 7 : d.w + d.U * 7 - (day + 6) % 7;
      }

      // If a time zone is specified, all fields are interpreted as UTC and then
      // offset according to the specified time zone.
      if ("Z" in d) {
        d.H += d.Z / 100 | 0;
        d.M += d.Z % 100;
        return utcDate(d);
      }

      // Otherwise, all fields are in local time.
      return localDate(d);
    };
  }

  function parseSpecifier(d, specifier, string, j) {
    var i = 0,
        n = specifier.length,
        m = string.length,
        c,
        parse;

    while (i < n) {
      if (j >= m) return -1;
      c = specifier.charCodeAt(i++);
      if (c === 37) {
        c = specifier.charAt(i++);
        parse = parses[c in pads ? specifier.charAt(i++) : c];
        if (!parse || ((j = parse(d, string, j)) < 0)) return -1;
      } else if (c != string.charCodeAt(j++)) {
        return -1;
      }
    }

    return j;
  }

  function parsePeriod(d, string, i) {
    var n = periodRe.exec(string.slice(i));
    return n ? (d.p = periodLookup.get(n[0].toLowerCase()), i + n[0].length) : -1;
  }

  function parseShortWeekday(d, string, i) {
    var n = shortWeekdayRe.exec(string.slice(i));
    return n ? (d.w = shortWeekdayLookup.get(n[0].toLowerCase()), i + n[0].length) : -1;
  }

  function parseWeekday(d, string, i) {
    var n = weekdayRe.exec(string.slice(i));
    return n ? (d.w = weekdayLookup.get(n[0].toLowerCase()), i + n[0].length) : -1;
  }

  function parseShortMonth(d, string, i) {
    var n = shortMonthRe.exec(string.slice(i));
    return n ? (d.m = shortMonthLookup.get(n[0].toLowerCase()), i + n[0].length) : -1;
  }

  function parseMonth(d, string, i) {
    var n = monthRe.exec(string.slice(i));
    return n ? (d.m = monthLookup.get(n[0].toLowerCase()), i + n[0].length) : -1;
  }

  function parseLocaleDateTime(d, string, i) {
    return parseSpecifier(d, locale_dateTime, string, i);
  }

  function parseLocaleDate(d, string, i) {
    return parseSpecifier(d, locale_date, string, i);
  }

  function parseLocaleTime(d, string, i) {
    return parseSpecifier(d, locale_time, string, i);
  }

  function formatShortWeekday(d) {
    return locale_shortWeekdays[d.getDay()];
  }

  function formatWeekday(d) {
    return locale_weekdays[d.getDay()];
  }

  function formatShortMonth(d) {
    return locale_shortMonths[d.getMonth()];
  }

  function formatMonth(d) {
    return locale_months[d.getMonth()];
  }

  function formatPeriod(d) {
    return locale_periods[+(d.getHours() >= 12)];
  }

  function formatQuarter(d) {
    return 1 + ~~(d.getMonth() / 3);
  }

  function formatUTCShortWeekday(d) {
    return locale_shortWeekdays[d.getUTCDay()];
  }

  function formatUTCWeekday(d) {
    return locale_weekdays[d.getUTCDay()];
  }

  function formatUTCShortMonth(d) {
    return locale_shortMonths[d.getUTCMonth()];
  }

  function formatUTCMonth(d) {
    return locale_months[d.getUTCMonth()];
  }

  function formatUTCPeriod(d) {
    return locale_periods[+(d.getUTCHours() >= 12)];
  }

  function formatUTCQuarter(d) {
    return 1 + ~~(d.getUTCMonth() / 3);
  }

  return {
    format: function(specifier) {
      var f = newFormat(specifier += "", formats);
      f.toString = function() { return specifier; };
      return f;
    },
    parse: function(specifier) {
      var p = newParse(specifier += "", false);
      p.toString = function() { return specifier; };
      return p;
    },
    utcFormat: function(specifier) {
      var f = newFormat(specifier += "", utcFormats);
      f.toString = function() { return specifier; };
      return f;
    },
    utcParse: function(specifier) {
      var p = newParse(specifier += "", true);
      p.toString = function() { return specifier; };
      return p;
    }
  };
}

var pads = {"-": "", "_": " ", "0": "0"},
    numberRe = /^\s*\d+/, // note: ignores next directive
    percentRe = /^%/,
    requoteRe = /[\\^$*+?|[\]().{}]/g;

function pad(value, fill, width) {
  var sign = value < 0 ? "-" : "",
      string = (sign ? -value : value) + "",
      length = string.length;
  return sign + (length < width ? new Array(width - length + 1).join(fill) + string : string);
}

function requote(s) {
  return s.replace(requoteRe, "\\$&");
}

function formatRe(names) {
  return new RegExp("^(?:" + names.map(requote).join("|") + ")", "i");
}

function formatLookup(names) {
  return new Map(names.map((name, i) => [name.toLowerCase(), i]));
}

function parseWeekdayNumberSunday(d, string, i) {
  var n = numberRe.exec(string.slice(i, i + 1));
  return n ? (d.w = +n[0], i + n[0].length) : -1;
}

function parseWeekdayNumberMonday(d, string, i) {
  var n = numberRe.exec(string.slice(i, i + 1));
  return n ? (d.u = +n[0], i + n[0].length) : -1;
}

function parseWeekNumberSunday(d, string, i) {
  var n = numberRe.exec(string.slice(i, i + 2));
  return n ? (d.U = +n[0], i + n[0].length) : -1;
}

function parseWeekNumberISO(d, string, i) {
  var n = numberRe.exec(string.slice(i, i + 2));
  return n ? (d.V = +n[0], i + n[0].length) : -1;
}

function parseWeekNumberMonday(d, string, i) {
  var n = numberRe.exec(string.slice(i, i + 2));
  return n ? (d.W = +n[0], i + n[0].length) : -1;
}

function parseFullYear(d, string, i) {
  var n = numberRe.exec(string.slice(i, i + 4));
  return n ? (d.y = +n[0], i + n[0].length) : -1;
}

function parseYear(d, string, i) {
  var n = numberRe.exec(string.slice(i, i + 2));
  return n ? (d.y = +n[0] + (+n[0] > 68 ? 1900 : 2000), i + n[0].length) : -1;
}

function parseZone(d, string, i) {
  var n = /^(Z)|([+-]\d\d)(?::?(\d\d))?/.exec(string.slice(i, i + 6));
  return n ? (d.Z = n[1] ? 0 : -(n[2] + (n[3] || "00")), i + n[0].length) : -1;
}

function parseQuarter(d, string, i) {
  var n = numberRe.exec(string.slice(i, i + 1));
  return n ? (d.q = n[0] * 3 - 3, i + n[0].length) : -1;
}

function parseMonthNumber(d, string, i) {
  var n = numberRe.exec(string.slice(i, i + 2));
  return n ? (d.m = n[0] - 1, i + n[0].length) : -1;
}

function parseDayOfMonth(d, string, i) {
  var n = numberRe.exec(string.slice(i, i + 2));
  return n ? (d.d = +n[0], i + n[0].length) : -1;
}

function parseDayOfYear(d, string, i) {
  var n = numberRe.exec(string.slice(i, i + 3));
  return n ? (d.m = 0, d.d = +n[0], i + n[0].length) : -1;
}

function parseHour24(d, string, i) {
  var n = numberRe.exec(string.slice(i, i + 2));
  return n ? (d.H = +n[0], i + n[0].length) : -1;
}

function parseMinutes(d, string, i) {
  var n = numberRe.exec(string.slice(i, i + 2));
  return n ? (d.M = +n[0], i + n[0].length) : -1;
}

function parseSeconds(d, string, i) {
  var n = numberRe.exec(string.slice(i, i + 2));
  return n ? (d.S = +n[0], i + n[0].length) : -1;
}

function parseMilliseconds(d, string, i) {
  var n = numberRe.exec(string.slice(i, i + 3));
  return n ? (d.L = +n[0], i + n[0].length) : -1;
}

function parseMicroseconds(d, string, i) {
  var n = numberRe.exec(string.slice(i, i + 6));
  return n ? (d.L = Math.floor(n[0] / 1000), i + n[0].length) : -1;
}

function parseLiteralPercent(d, string, i) {
  var n = percentRe.exec(string.slice(i, i + 1));
  return n ? i + n[0].length : -1;
}

function parseUnixTimestamp(d, string, i) {
  var n = numberRe.exec(string.slice(i));
  return n ? (d.Q = +n[0], i + n[0].length) : -1;
}

function parseUnixTimestampSeconds(d, string, i) {
  var n = numberRe.exec(string.slice(i));
  return n ? (d.s = +n[0], i + n[0].length) : -1;
}

function formatDayOfMonth(d, p) {
  return pad(d.getDate(), p, 2);
}

function formatHour24(d, p) {
  return pad(d.getHours(), p, 2);
}

function formatHour12(d, p) {
  return pad(d.getHours() % 12 || 12, p, 2);
}

function formatDayOfYear(d, p) {
  return pad(1 + timeDay.count(timeYear(d), d), p, 3);
}

function formatMilliseconds(d, p) {
  return pad(d.getMilliseconds(), p, 3);
}

function formatMicroseconds(d, p) {
  return formatMilliseconds(d, p) + "000";
}

function formatMonthNumber(d, p) {
  return pad(d.getMonth() + 1, p, 2);
}

function formatMinutes(d, p) {
  return pad(d.getMinutes(), p, 2);
}

function formatSeconds(d, p) {
  return pad(d.getSeconds(), p, 2);
}

function formatWeekdayNumberMonday(d) {
  var day = d.getDay();
  return day === 0 ? 7 : day;
}

function formatWeekNumberSunday(d, p) {
  return pad(timeSunday.count(timeYear(d) - 1, d), p, 2);
}

function dISO(d) {
  var day = d.getDay();
  return (day >= 4 || day === 0) ? timeThursday(d) : timeThursday.ceil(d);
}

function formatWeekNumberISO(d, p) {
  d = dISO(d);
  return pad(timeThursday.count(timeYear(d), d) + (timeYear(d).getDay() === 4), p, 2);
}

function formatWeekdayNumberSunday(d) {
  return d.getDay();
}

function formatWeekNumberMonday(d, p) {
  return pad(timeMonday.count(timeYear(d) - 1, d), p, 2);
}

function formatYear(d, p) {
  return pad(d.getFullYear() % 100, p, 2);
}

function formatYearISO(d, p) {
  d = dISO(d);
  return pad(d.getFullYear() % 100, p, 2);
}

function formatFullYear(d, p) {
  return pad(d.getFullYear() % 10000, p, 4);
}

function formatFullYearISO(d, p) {
  var day = d.getDay();
  d = (day >= 4 || day === 0) ? timeThursday(d) : timeThursday.ceil(d);
  return pad(d.getFullYear() % 10000, p, 4);
}

function formatZone(d) {
  var z = d.getTimezoneOffset();
  return (z > 0 ? "-" : (z *= -1, "+"))
      + pad(z / 60 | 0, "0", 2)
      + pad(z % 60, "0", 2);
}

function formatUTCDayOfMonth(d, p) {
  return pad(d.getUTCDate(), p, 2);
}

function formatUTCHour24(d, p) {
  return pad(d.getUTCHours(), p, 2);
}

function formatUTCHour12(d, p) {
  return pad(d.getUTCHours() % 12 || 12, p, 2);
}

function formatUTCDayOfYear(d, p) {
  return pad(1 + utcDay.count(utcYear(d), d), p, 3);
}

function formatUTCMilliseconds(d, p) {
  return pad(d.getUTCMilliseconds(), p, 3);
}

function formatUTCMicroseconds(d, p) {
  return formatUTCMilliseconds(d, p) + "000";
}

function formatUTCMonthNumber(d, p) {
  return pad(d.getUTCMonth() + 1, p, 2);
}

function formatUTCMinutes(d, p) {
  return pad(d.getUTCMinutes(), p, 2);
}

function formatUTCSeconds(d, p) {
  return pad(d.getUTCSeconds(), p, 2);
}

function formatUTCWeekdayNumberMonday(d) {
  var dow = d.getUTCDay();
  return dow === 0 ? 7 : dow;
}

function formatUTCWeekNumberSunday(d, p) {
  return pad(utcSunday.count(utcYear(d) - 1, d), p, 2);
}

function UTCdISO(d) {
  var day = d.getUTCDay();
  return (day >= 4 || day === 0) ? utcThursday(d) : utcThursday.ceil(d);
}

function formatUTCWeekNumberISO(d, p) {
  d = UTCdISO(d);
  return pad(utcThursday.count(utcYear(d), d) + (utcYear(d).getUTCDay() === 4), p, 2);
}

function formatUTCWeekdayNumberSunday(d) {
  return d.getUTCDay();
}

function formatUTCWeekNumberMonday(d, p) {
  return pad(utcMonday.count(utcYear(d) - 1, d), p, 2);
}

function formatUTCYear(d, p) {
  return pad(d.getUTCFullYear() % 100, p, 2);
}

function formatUTCYearISO(d, p) {
  d = UTCdISO(d);
  return pad(d.getUTCFullYear() % 100, p, 2);
}

function formatUTCFullYear(d, p) {
  return pad(d.getUTCFullYear() % 10000, p, 4);
}

function formatUTCFullYearISO(d, p) {
  var day = d.getUTCDay();
  d = (day >= 4 || day === 0) ? utcThursday(d) : utcThursday.ceil(d);
  return pad(d.getUTCFullYear() % 10000, p, 4);
}

function formatUTCZone() {
  return "+0000";
}

function formatLiteralPercent() {
  return "%";
}

function formatUnixTimestamp(d) {
  return +d;
}

function formatUnixTimestampSeconds(d) {
  return Math.floor(+d / 1000);
}

var locale;
var timeFormat;
var timeParse;
var utcFormat;
var utcParse;

defaultLocale({
  dateTime: "%x, %X",
  date: "%-m/%-d/%Y",
  time: "%-I:%M:%S %p",
  periods: ["AM", "PM"],
  days: ["Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"],
  shortDays: ["Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"],
  months: ["January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"],
  shortMonths: ["Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"]
});

function defaultLocale(definition) {
  locale = formatLocale(definition);
  timeFormat = locale.format;
  timeParse = locale.parse;
  utcFormat = locale.utcFormat;
  utcParse = locale.utcParse;
  return locale;
}

var isoSpecifier = "%Y-%m-%dT%H:%M:%S.%LZ";

function formatIsoNative(date) {
  return date.toISOString();
}

var formatIso = Date.prototype.toISOString
    ? formatIsoNative
    : utcFormat(isoSpecifier);

function parseIsoNative(string) {
  var date = new Date(string);
  return isNaN(date) ? null : date;
}

var parseIso = +new Date("2000-01-01T00:00:00.000Z")
    ? parseIsoNative
    : utcParse(isoSpecifier);

function date(t) {
  return new Date(t);
}

function number(t) {
  return t instanceof Date ? +t : +new Date(+t);
}

function calendar(ticks, tickInterval, year, month, week, day, hour, minute, second, format) {
  var scale = continuous(),
      invert = scale.invert,
      domain = scale.domain;

  var formatMillisecond = format(".%L"),
      formatSecond = format(":%S"),
      formatMinute = format("%I:%M"),
      formatHour = format("%I %p"),
      formatDay = format("%a %d"),
      formatWeek = format("%b %d"),
      formatMonth = format("%B"),
      formatYear = format("%Y");

  function tickFormat(date) {
    return (second(date) < date ? formatMillisecond
        : minute(date) < date ? formatSecond
        : hour(date) < date ? formatMinute
        : day(date) < date ? formatHour
        : month(date) < date ? (week(date) < date ? formatDay : formatWeek)
        : year(date) < date ? formatMonth
        : formatYear)(date);
  }

  scale.invert = function(y) {
    return new Date(invert(y));
  };

  scale.domain = function(_) {
    return arguments.length ? domain(Array.from(_, number)) : domain().map(date);
  };

  scale.ticks = function(interval) {
    var d = domain();
    return ticks(d[0], d[d.length - 1], interval == null ? 10 : interval);
  };

  scale.tickFormat = function(count, specifier) {
    return specifier == null ? tickFormat : format(specifier);
  };

  scale.nice = function(interval) {
    var d = domain();
    if (!interval || typeof interval.range !== "function") interval = tickInterval(d[0], d[d.length - 1], interval == null ? 10 : interval);
    return interval ? domain(nice(d, interval)) : scale;
  };

  scale.copy = function() {
    return copy$1(scale, calendar(ticks, tickInterval, year, month, week, day, hour, minute, second, format));
  };

  return scale;
}

function time() {
  return initRange.apply(calendar(timeTicks, timeTickInterval, timeYear, timeMonth, timeSunday, timeDay, timeHour, timeMinute, second, timeFormat).domain([new Date(2000, 0, 1), new Date(2000, 0, 2)]), arguments);
}

function utcTime() {
  return initRange.apply(calendar(utcTicks, utcTickInterval, utcYear, utcMonth, utcSunday, utcDay, utcHour, utcMinute, second, utcFormat).domain([Date.UTC(2000, 0, 1), Date.UTC(2000, 0, 2)]), arguments);
}

function transformer$1() {
  var x0 = 0,
      x1 = 1,
      t0,
      t1,
      k10,
      transform,
      interpolator = identity$2,
      clamp = false,
      unknown;

  function scale(x) {
    return x == null || isNaN(x = +x) ? unknown : interpolator(k10 === 0 ? 0.5 : (x = (transform(x) - t0) * k10, clamp ? Math.max(0, Math.min(1, x)) : x));
  }

  scale.domain = function(_) {
    return arguments.length ? ([x0, x1] = _, t0 = transform(x0 = +x0), t1 = transform(x1 = +x1), k10 = t0 === t1 ? 0 : 1 / (t1 - t0), scale) : [x0, x1];
  };

  scale.clamp = function(_) {
    return arguments.length ? (clamp = !!_, scale) : clamp;
  };

  scale.interpolator = function(_) {
    return arguments.length ? (interpolator = _, scale) : interpolator;
  };

  function range(interpolate) {
    return function(_) {
      var r0, r1;
      return arguments.length ? ([r0, r1] = _, interpolator = interpolate(r0, r1), scale) : [interpolator(0), interpolator(1)];
    };
  }

  scale.range = range(interpolate$1);

  scale.rangeRound = range(interpolateRound);

  scale.unknown = function(_) {
    return arguments.length ? (unknown = _, scale) : unknown;
  };

  return function(t) {
    transform = t, t0 = t(x0), t1 = t(x1), k10 = t0 === t1 ? 0 : 1 / (t1 - t0);
    return scale;
  };
}

function copy(source, target) {
  return target
      .domain(source.domain())
      .interpolator(source.interpolator())
      .clamp(source.clamp())
      .unknown(source.unknown());
}

function sequential() {
  var scale = linearish(transformer$1()(identity$2));

  scale.copy = function() {
    return copy(scale, sequential());
  };

  return initInterpolator.apply(scale, arguments);
}

function sequentialLog() {
  var scale = loggish(transformer$1()).domain([1, 10]);

  scale.copy = function() {
    return copy(scale, sequentialLog()).base(scale.base());
  };

  return initInterpolator.apply(scale, arguments);
}

function sequentialSymlog() {
  var scale = symlogish(transformer$1());

  scale.copy = function() {
    return copy(scale, sequentialSymlog()).constant(scale.constant());
  };

  return initInterpolator.apply(scale, arguments);
}

function sequentialPow() {
  var scale = powish(transformer$1());

  scale.copy = function() {
    return copy(scale, sequentialPow()).exponent(scale.exponent());
  };

  return initInterpolator.apply(scale, arguments);
}

function sequentialSqrt() {
  return sequentialPow.apply(null, arguments).exponent(0.5);
}

function sequentialQuantile() {
  var domain = [],
      interpolator = identity$2;

  function scale(x) {
    if (x != null && !isNaN(x = +x)) return interpolator((bisectRight(domain, x, 1) - 1) / (domain.length - 1));
  }

  scale.domain = function(_) {
    if (!arguments.length) return domain.slice();
    domain = [];
    for (let d of _) if (d != null && !isNaN(d = +d)) domain.push(d);
    domain.sort(ascending);
    return scale;
  };

  scale.interpolator = function(_) {
    return arguments.length ? (interpolator = _, scale) : interpolator;
  };

  scale.range = function() {
    return domain.map((d, i) => interpolator(i / (domain.length - 1)));
  };

  scale.quantiles = function(n) {
    return Array.from({length: n + 1}, (_, i) => quantile$1(domain, i / n));
  };

  scale.copy = function() {
    return sequentialQuantile(interpolator).domain(domain);
  };

  return initInterpolator.apply(scale, arguments);
}

function transformer() {
  var x0 = 0,
      x1 = 0.5,
      x2 = 1,
      s = 1,
      t0,
      t1,
      t2,
      k10,
      k21,
      interpolator = identity$2,
      transform,
      clamp = false,
      unknown;

  function scale(x) {
    return isNaN(x = +x) ? unknown : (x = 0.5 + ((x = +transform(x)) - t1) * (s * x < s * t1 ? k10 : k21), interpolator(clamp ? Math.max(0, Math.min(1, x)) : x));
  }

  scale.domain = function(_) {
    return arguments.length ? ([x0, x1, x2] = _, t0 = transform(x0 = +x0), t1 = transform(x1 = +x1), t2 = transform(x2 = +x2), k10 = t0 === t1 ? 0 : 0.5 / (t1 - t0), k21 = t1 === t2 ? 0 : 0.5 / (t2 - t1), s = t1 < t0 ? -1 : 1, scale) : [x0, x1, x2];
  };

  scale.clamp = function(_) {
    return arguments.length ? (clamp = !!_, scale) : clamp;
  };

  scale.interpolator = function(_) {
    return arguments.length ? (interpolator = _, scale) : interpolator;
  };

  function range(interpolate) {
    return function(_) {
      var r0, r1, r2;
      return arguments.length ? ([r0, r1, r2] = _, interpolator = piecewise(interpolate, [r0, r1, r2]), scale) : [interpolator(0), interpolator(0.5), interpolator(1)];
    };
  }

  scale.range = range(interpolate$1);

  scale.rangeRound = range(interpolateRound);

  scale.unknown = function(_) {
    return arguments.length ? (unknown = _, scale) : unknown;
  };

  return function(t) {
    transform = t, t0 = t(x0), t1 = t(x1), t2 = t(x2), k10 = t0 === t1 ? 0 : 0.5 / (t1 - t0), k21 = t1 === t2 ? 0 : 0.5 / (t2 - t1), s = t1 < t0 ? -1 : 1;
    return scale;
  };
}

function diverging() {
  var scale = linearish(transformer()(identity$2));

  scale.copy = function() {
    return copy(scale, diverging());
  };

  return initInterpolator.apply(scale, arguments);
}

function divergingLog() {
  var scale = loggish(transformer()).domain([0.1, 1, 10]);

  scale.copy = function() {
    return copy(scale, divergingLog()).base(scale.base());
  };

  return initInterpolator.apply(scale, arguments);
}

function divergingSymlog() {
  var scale = symlogish(transformer());

  scale.copy = function() {
    return copy(scale, divergingSymlog()).constant(scale.constant());
  };

  return initInterpolator.apply(scale, arguments);
}

function divergingPow() {
  var scale = powish(transformer());

  scale.copy = function() {
    return copy(scale, divergingPow()).exponent(scale.exponent());
  };

  return initInterpolator.apply(scale, arguments);
}

function divergingSqrt() {
  return divergingPow.apply(null, arguments).exponent(0.5);
}

function constant(x) {
  return function constant() {
    return x;
  };
}

const abs = Math.abs;
const atan2 = Math.atan2;
const cos = Math.cos;
const max = Math.max;
const min = Math.min;
const sin = Math.sin;
const sqrt = Math.sqrt;

const epsilon = 1e-12;
const pi = Math.PI;
const halfPi = pi / 2;
const tau = 2 * pi;

function acos(x) {
  return x > 1 ? 0 : x < -1 ? pi : Math.acos(x);
}

function asin(x) {
  return x >= 1 ? halfPi : x <= -1 ? -halfPi : Math.asin(x);
}

function withPath(shape) {
  let digits = 3;

  shape.digits = function(_) {
    if (!arguments.length) return digits;
    if (_ == null) {
      digits = null;
    } else {
      const d = Math.floor(_);
      if (!(d >= 0)) throw new RangeError(`invalid digits: ${_}`);
      digits = d;
    }
    return shape;
  };

  return () => new Path(digits);
}

function arcInnerRadius(d) {
  return d.innerRadius;
}

function arcOuterRadius(d) {
  return d.outerRadius;
}

function arcStartAngle(d) {
  return d.startAngle;
}

function arcEndAngle(d) {
  return d.endAngle;
}

function arcPadAngle(d) {
  return d && d.padAngle; // Note: optional!
}

function intersect(x0, y0, x1, y1, x2, y2, x3, y3) {
  var x10 = x1 - x0, y10 = y1 - y0,
      x32 = x3 - x2, y32 = y3 - y2,
      t = y32 * x10 - x32 * y10;
  if (t * t < epsilon) return;
  t = (x32 * (y0 - y2) - y32 * (x0 - x2)) / t;
  return [x0 + t * x10, y0 + t * y10];
}

// Compute perpendicular offset line of length rc.
// http://mathworld.wolfram.com/Circle-LineIntersection.html
function cornerTangents(x0, y0, x1, y1, r1, rc, cw) {
  var x01 = x0 - x1,
      y01 = y0 - y1,
      lo = (cw ? rc : -rc) / sqrt(x01 * x01 + y01 * y01),
      ox = lo * y01,
      oy = -lo * x01,
      x11 = x0 + ox,
      y11 = y0 + oy,
      x10 = x1 + ox,
      y10 = y1 + oy,
      x00 = (x11 + x10) / 2,
      y00 = (y11 + y10) / 2,
      dx = x10 - x11,
      dy = y10 - y11,
      d2 = dx * dx + dy * dy,
      r = r1 - rc,
      D = x11 * y10 - x10 * y11,
      d = (dy < 0 ? -1 : 1) * sqrt(max(0, r * r * d2 - D * D)),
      cx0 = (D * dy - dx * d) / d2,
      cy0 = (-D * dx - dy * d) / d2,
      cx1 = (D * dy + dx * d) / d2,
      cy1 = (-D * dx + dy * d) / d2,
      dx0 = cx0 - x00,
      dy0 = cy0 - y00,
      dx1 = cx1 - x00,
      dy1 = cy1 - y00;

  // Pick the closer of the two intersection points.
  // TODO Is there a faster way to determine which intersection to use?
  if (dx0 * dx0 + dy0 * dy0 > dx1 * dx1 + dy1 * dy1) cx0 = cx1, cy0 = cy1;

  return {
    cx: cx0,
    cy: cy0,
    x01: -ox,
    y01: -oy,
    x11: cx0 * (r1 / r - 1),
    y11: cy0 * (r1 / r - 1)
  };
}

function arc() {
  var innerRadius = arcInnerRadius,
      outerRadius = arcOuterRadius,
      cornerRadius = constant(0),
      padRadius = null,
      startAngle = arcStartAngle,
      endAngle = arcEndAngle,
      padAngle = arcPadAngle,
      context = null,
      path = withPath(arc);

  function arc() {
    var buffer,
        r,
        r0 = +innerRadius.apply(this, arguments),
        r1 = +outerRadius.apply(this, arguments),
        a0 = startAngle.apply(this, arguments) - halfPi,
        a1 = endAngle.apply(this, arguments) - halfPi,
        da = abs(a1 - a0),
        cw = a1 > a0;

    if (!context) context = buffer = path();

    // Ensure that the outer radius is always larger than the inner radius.
    if (r1 < r0) r = r1, r1 = r0, r0 = r;

    // Is it a point?
    if (!(r1 > epsilon)) context.moveTo(0, 0);

    // Or is it a circle or annulus?
    else if (da > tau - epsilon) {
      context.moveTo(r1 * cos(a0), r1 * sin(a0));
      context.arc(0, 0, r1, a0, a1, !cw);
      if (r0 > epsilon) {
        context.moveTo(r0 * cos(a1), r0 * sin(a1));
        context.arc(0, 0, r0, a1, a0, cw);
      }
    }

    // Or is it a circular or annular sector?
    else {
      var a01 = a0,
          a11 = a1,
          a00 = a0,
          a10 = a1,
          da0 = da,
          da1 = da,
          ap = padAngle.apply(this, arguments) / 2,
          rp = (ap > epsilon) && (padRadius ? +padRadius.apply(this, arguments) : sqrt(r0 * r0 + r1 * r1)),
          rc = min(abs(r1 - r0) / 2, +cornerRadius.apply(this, arguments)),
          rc0 = rc,
          rc1 = rc,
          t0,
          t1;

      // Apply padding? Note that since r1 ≥ r0, da1 ≥ da0.
      if (rp > epsilon) {
        var p0 = asin(rp / r0 * sin(ap)),
            p1 = asin(rp / r1 * sin(ap));
        if ((da0 -= p0 * 2) > epsilon) p0 *= (cw ? 1 : -1), a00 += p0, a10 -= p0;
        else da0 = 0, a00 = a10 = (a0 + a1) / 2;
        if ((da1 -= p1 * 2) > epsilon) p1 *= (cw ? 1 : -1), a01 += p1, a11 -= p1;
        else da1 = 0, a01 = a11 = (a0 + a1) / 2;
      }

      var x01 = r1 * cos(a01),
          y01 = r1 * sin(a01),
          x10 = r0 * cos(a10),
          y10 = r0 * sin(a10);

      // Apply rounded corners?
      if (rc > epsilon) {
        var x11 = r1 * cos(a11),
            y11 = r1 * sin(a11),
            x00 = r0 * cos(a00),
            y00 = r0 * sin(a00),
            oc;

        // Restrict the corner radius according to the sector angle. If this
        // intersection fails, it’s probably because the arc is too small, so
        // disable the corner radius entirely.
        if (da < pi) {
          if (oc = intersect(x01, y01, x00, y00, x11, y11, x10, y10)) {
            var ax = x01 - oc[0],
                ay = y01 - oc[1],
                bx = x11 - oc[0],
                by = y11 - oc[1],
                kc = 1 / sin(acos((ax * bx + ay * by) / (sqrt(ax * ax + ay * ay) * sqrt(bx * bx + by * by))) / 2),
                lc = sqrt(oc[0] * oc[0] + oc[1] * oc[1]);
            rc0 = min(rc, (r0 - lc) / (kc - 1));
            rc1 = min(rc, (r1 - lc) / (kc + 1));
          } else {
            rc0 = rc1 = 0;
          }
        }
      }

      // Is the sector collapsed to a line?
      if (!(da1 > epsilon)) context.moveTo(x01, y01);

      // Does the sector’s outer ring have rounded corners?
      else if (rc1 > epsilon) {
        t0 = cornerTangents(x00, y00, x01, y01, r1, rc1, cw);
        t1 = cornerTangents(x11, y11, x10, y10, r1, rc1, cw);

        context.moveTo(t0.cx + t0.x01, t0.cy + t0.y01);

        // Have the corners merged?
        if (rc1 < rc) context.arc(t0.cx, t0.cy, rc1, atan2(t0.y01, t0.x01), atan2(t1.y01, t1.x01), !cw);

        // Otherwise, draw the two corners and the ring.
        else {
          context.arc(t0.cx, t0.cy, rc1, atan2(t0.y01, t0.x01), atan2(t0.y11, t0.x11), !cw);
          context.arc(0, 0, r1, atan2(t0.cy + t0.y11, t0.cx + t0.x11), atan2(t1.cy + t1.y11, t1.cx + t1.x11), !cw);
          context.arc(t1.cx, t1.cy, rc1, atan2(t1.y11, t1.x11), atan2(t1.y01, t1.x01), !cw);
        }
      }

      // Or is the outer ring just a circular arc?
      else context.moveTo(x01, y01), context.arc(0, 0, r1, a01, a11, !cw);

      // Is there no inner ring, and it’s a circular sector?
      // Or perhaps it’s an annular sector collapsed due to padding?
      if (!(r0 > epsilon) || !(da0 > epsilon)) context.lineTo(x10, y10);

      // Does the sector’s inner ring (or point) have rounded corners?
      else if (rc0 > epsilon) {
        t0 = cornerTangents(x10, y10, x11, y11, r0, -rc0, cw);
        t1 = cornerTangents(x01, y01, x00, y00, r0, -rc0, cw);

        context.lineTo(t0.cx + t0.x01, t0.cy + t0.y01);

        // Have the corners merged?
        if (rc0 < rc) context.arc(t0.cx, t0.cy, rc0, atan2(t0.y01, t0.x01), atan2(t1.y01, t1.x01), !cw);

        // Otherwise, draw the two corners and the ring.
        else {
          context.arc(t0.cx, t0.cy, rc0, atan2(t0.y01, t0.x01), atan2(t0.y11, t0.x11), !cw);
          context.arc(0, 0, r0, atan2(t0.cy + t0.y11, t0.cx + t0.x11), atan2(t1.cy + t1.y11, t1.cx + t1.x11), cw);
          context.arc(t1.cx, t1.cy, rc0, atan2(t1.y11, t1.x11), atan2(t1.y01, t1.x01), !cw);
        }
      }

      // Or is the inner ring just a circular arc?
      else context.arc(0, 0, r0, a10, a00, cw);
    }

    context.closePath();

    if (buffer) return context = null, buffer + "" || null;
  }

  arc.centroid = function() {
    var r = (+innerRadius.apply(this, arguments) + +outerRadius.apply(this, arguments)) / 2,
        a = (+startAngle.apply(this, arguments) + +endAngle.apply(this, arguments)) / 2 - pi / 2;
    return [cos(a) * r, sin(a) * r];
  };

  arc.innerRadius = function(_) {
    return arguments.length ? (innerRadius = typeof _ === "function" ? _ : constant(+_), arc) : innerRadius;
  };

  arc.outerRadius = function(_) {
    return arguments.length ? (outerRadius = typeof _ === "function" ? _ : constant(+_), arc) : outerRadius;
  };

  arc.cornerRadius = function(_) {
    return arguments.length ? (cornerRadius = typeof _ === "function" ? _ : constant(+_), arc) : cornerRadius;
  };

  arc.padRadius = function(_) {
    return arguments.length ? (padRadius = _ == null ? null : typeof _ === "function" ? _ : constant(+_), arc) : padRadius;
  };

  arc.startAngle = function(_) {
    return arguments.length ? (startAngle = typeof _ === "function" ? _ : constant(+_), arc) : startAngle;
  };

  arc.endAngle = function(_) {
    return arguments.length ? (endAngle = typeof _ === "function" ? _ : constant(+_), arc) : endAngle;
  };

  arc.padAngle = function(_) {
    return arguments.length ? (padAngle = typeof _ === "function" ? _ : constant(+_), arc) : padAngle;
  };

  arc.context = function(_) {
    return arguments.length ? ((context = _ == null ? null : _), arc) : context;
  };

  return arc;
}

var frame = 0, // is an animation frame pending?
    timeout$1 = 0, // is a timeout pending?
    interval = 0, // are any timers active?
    pokeDelay = 1000, // how frequently we check for clock skew
    taskHead,
    taskTail,
    clockLast = 0,
    clockNow = 0,
    clockSkew = 0,
    clock = typeof performance === "object" && performance.now ? performance : Date,
    setFrame = typeof window === "object" && window.requestAnimationFrame ? window.requestAnimationFrame.bind(window) : function(f) { setTimeout(f, 17); };

function now() {
  return clockNow || (setFrame(clearNow), clockNow = clock.now() + clockSkew);
}

function clearNow() {
  clockNow = 0;
}

function Timer() {
  this._call =
  this._time =
  this._next = null;
}

Timer.prototype = timer.prototype = {
  constructor: Timer,
  restart: function(callback, delay, time) {
    if (typeof callback !== "function") throw new TypeError("callback is not a function");
    time = (time == null ? now() : +time) + (delay == null ? 0 : +delay);
    if (!this._next && taskTail !== this) {
      if (taskTail) taskTail._next = this;
      else taskHead = this;
      taskTail = this;
    }
    this._call = callback;
    this._time = time;
    sleep();
  },
  stop: function() {
    if (this._call) {
      this._call = null;
      this._time = Infinity;
      sleep();
    }
  }
};

function timer(callback, delay, time) {
  var t = new Timer;
  t.restart(callback, delay, time);
  return t;
}

function timerFlush() {
  now(); // Get the current time, if not already set.
  ++frame; // Pretend we’ve set an alarm, if we haven’t already.
  var t = taskHead, e;
  while (t) {
    if ((e = clockNow - t._time) >= 0) t._call.call(undefined, e);
    t = t._next;
  }
  --frame;
}

function wake() {
  clockNow = (clockLast = clock.now()) + clockSkew;
  frame = timeout$1 = 0;
  try {
    timerFlush();
  } finally {
    frame = 0;
    nap();
    clockNow = 0;
  }
}

function poke() {
  var now = clock.now(), delay = now - clockLast;
  if (delay > pokeDelay) clockSkew -= delay, clockLast = now;
}

function nap() {
  var t0, t1 = taskHead, t2, time = Infinity;
  while (t1) {
    if (t1._call) {
      if (time > t1._time) time = t1._time;
      t0 = t1, t1 = t1._next;
    } else {
      t2 = t1._next, t1._next = null;
      t1 = t0 ? t0._next = t2 : taskHead = t2;
    }
  }
  taskTail = t0;
  sleep(time);
}

function sleep(time) {
  if (frame) return; // Soonest alarm already set, or will be.
  if (timeout$1) timeout$1 = clearTimeout(timeout$1);
  var delay = time - clockNow; // Strictly less than if we recomputed clockNow.
  if (delay > 24) {
    if (time < Infinity) timeout$1 = setTimeout(wake, time - clock.now() - clockSkew);
    if (interval) interval = clearInterval(interval);
  } else {
    if (!interval) clockLast = clock.now(), interval = setInterval(poke, pokeDelay);
    frame = 1, setFrame(wake);
  }
}

function timeout(callback, delay, time) {
  var t = new Timer;
  delay = delay == null ? 0 : +delay;
  t.restart(elapsed => {
    t.stop();
    callback(elapsed + delay);
  }, delay, time);
  return t;
}

var emptyOn = dispatch("start", "end", "cancel", "interrupt");
var emptyTween = [];

var CREATED = 0;
var SCHEDULED = 1;
var STARTING = 2;
var STARTED = 3;
var RUNNING = 4;
var ENDING = 5;
var ENDED = 6;

function schedule(node, name, id, index, group, timing) {
  var schedules = node.__transition;
  if (!schedules) node.__transition = {};
  else if (id in schedules) return;
  create(node, id, {
    name: name,
    index: index, // For context during callback.
    group: group, // For context during callback.
    on: emptyOn,
    tween: emptyTween,
    time: timing.time,
    delay: timing.delay,
    duration: timing.duration,
    ease: timing.ease,
    timer: null,
    state: CREATED
  });
}

function init(node, id) {
  var schedule = get(node, id);
  if (schedule.state > CREATED) throw new Error("too late; already scheduled");
  return schedule;
}

function set(node, id) {
  var schedule = get(node, id);
  if (schedule.state > STARTED) throw new Error("too late; already running");
  return schedule;
}

function get(node, id) {
  var schedule = node.__transition;
  if (!schedule || !(schedule = schedule[id])) throw new Error("transition not found");
  return schedule;
}

function create(node, id, self) {
  var schedules = node.__transition,
      tween;

  // Initialize the self timer when the transition is created.
  // Note the actual delay is not known until the first callback!
  schedules[id] = self;
  self.timer = timer(schedule, 0, self.time);

  function schedule(elapsed) {
    self.state = SCHEDULED;
    self.timer.restart(start, self.delay, self.time);

    // If the elapsed delay is less than our first sleep, start immediately.
    if (self.delay <= elapsed) start(elapsed - self.delay);
  }

  function start(elapsed) {
    var i, j, n, o;

    // If the state is not SCHEDULED, then we previously errored on start.
    if (self.state !== SCHEDULED) return stop();

    for (i in schedules) {
      o = schedules[i];
      if (o.name !== self.name) continue;

      // While this element already has a starting transition during this frame,
      // defer starting an interrupting transition until that transition has a
      // chance to tick (and possibly end); see d3/d3-transition#54!
      if (o.state === STARTED) return timeout(start);

      // Interrupt the active transition, if any.
      if (o.state === RUNNING) {
        o.state = ENDED;
        o.timer.stop();
        o.on.call("interrupt", node, node.__data__, o.index, o.group);
        delete schedules[i];
      }

      // Cancel any pre-empted transitions.
      else if (+i < id) {
        o.state = ENDED;
        o.timer.stop();
        o.on.call("cancel", node, node.__data__, o.index, o.group);
        delete schedules[i];
      }
    }

    // Defer the first tick to end of the current frame; see d3/d3#1576.
    // Note the transition may be canceled after start and before the first tick!
    // Note this must be scheduled before the start event; see d3/d3-transition#16!
    // Assuming this is successful, subsequent callbacks go straight to tick.
    timeout(function() {
      if (self.state === STARTED) {
        self.state = RUNNING;
        self.timer.restart(tick, self.delay, self.time);
        tick(elapsed);
      }
    });

    // Dispatch the start event.
    // Note this must be done before the tween are initialized.
    self.state = STARTING;
    self.on.call("start", node, node.__data__, self.index, self.group);
    if (self.state !== STARTING) return; // interrupted
    self.state = STARTED;

    // Initialize the tween, deleting null tween.
    tween = new Array(n = self.tween.length);
    for (i = 0, j = -1; i < n; ++i) {
      if (o = self.tween[i].value.call(node, node.__data__, self.index, self.group)) {
        tween[++j] = o;
      }
    }
    tween.length = j + 1;
  }

  function tick(elapsed) {
    var t = elapsed < self.duration ? self.ease.call(null, elapsed / self.duration) : (self.timer.restart(stop), self.state = ENDING, 1),
        i = -1,
        n = tween.length;

    while (++i < n) {
      tween[i].call(node, t);
    }

    // Dispatch the end event.
    if (self.state === ENDING) {
      self.on.call("end", node, node.__data__, self.index, self.group);
      stop();
    }
  }

  function stop() {
    self.state = ENDED;
    self.timer.stop();
    delete schedules[id];
    for (var i in schedules) return; // eslint-disable-line no-unused-vars
    delete node.__transition;
  }
}

function interrupt(node, name) {
  var schedules = node.__transition,
      schedule,
      active,
      empty = true,
      i;

  if (!schedules) return;

  name = name == null ? null : name + "";

  for (i in schedules) {
    if ((schedule = schedules[i]).name !== name) { empty = false; continue; }
    active = schedule.state > STARTING && schedule.state < ENDING;
    schedule.state = ENDED;
    schedule.timer.stop();
    schedule.on.call(active ? "interrupt" : "cancel", node, node.__data__, schedule.index, schedule.group);
    delete schedules[i];
  }

  if (empty) delete node.__transition;
}

function selection_interrupt(name) {
  return this.each(function() {
    interrupt(this, name);
  });
}

function tweenRemove(id, name) {
  var tween0, tween1;
  return function() {
    var schedule = set(this, id),
        tween = schedule.tween;

    // If this node shared tween with the previous node,
    // just assign the updated shared tween and we’re done!
    // Otherwise, copy-on-write.
    if (tween !== tween0) {
      tween1 = tween0 = tween;
      for (var i = 0, n = tween1.length; i < n; ++i) {
        if (tween1[i].name === name) {
          tween1 = tween1.slice();
          tween1.splice(i, 1);
          break;
        }
      }
    }

    schedule.tween = tween1;
  };
}

function tweenFunction(id, name, value) {
  var tween0, tween1;
  if (typeof value !== "function") throw new Error;
  return function() {
    var schedule = set(this, id),
        tween = schedule.tween;

    // If this node shared tween with the previous node,
    // just assign the updated shared tween and we’re done!
    // Otherwise, copy-on-write.
    if (tween !== tween0) {
      tween1 = (tween0 = tween).slice();
      for (var t = {name: name, value: value}, i = 0, n = tween1.length; i < n; ++i) {
        if (tween1[i].name === name) {
          tween1[i] = t;
          break;
        }
      }
      if (i === n) tween1.push(t);
    }

    schedule.tween = tween1;
  };
}

function transition_tween(name, value) {
  var id = this._id;

  name += "";

  if (arguments.length < 2) {
    var tween = get(this.node(), id).tween;
    for (var i = 0, n = tween.length, t; i < n; ++i) {
      if ((t = tween[i]).name === name) {
        return t.value;
      }
    }
    return null;
  }

  return this.each((value == null ? tweenRemove : tweenFunction)(id, name, value));
}

function tweenValue(transition, name, value) {
  var id = transition._id;

  transition.each(function() {
    var schedule = set(this, id);
    (schedule.value || (schedule.value = {}))[name] = value.apply(this, arguments);
  });

  return function(node) {
    return get(node, id).value[name];
  };
}

function interpolate(a, b) {
  var c;
  return (typeof b === "number" ? interpolateNumber
      : b instanceof color ? interpolateRgb
      : (c = color(b)) ? (b = c, interpolateRgb)
      : interpolateString)(a, b);
}

function attrRemove(name) {
  return function() {
    this.removeAttribute(name);
  };
}

function attrRemoveNS(fullname) {
  return function() {
    this.removeAttributeNS(fullname.space, fullname.local);
  };
}

function attrConstant(name, interpolate, value1) {
  var string00,
      string1 = value1 + "",
      interpolate0;
  return function() {
    var string0 = this.getAttribute(name);
    return string0 === string1 ? null
        : string0 === string00 ? interpolate0
        : interpolate0 = interpolate(string00 = string0, value1);
  };
}

function attrConstantNS(fullname, interpolate, value1) {
  var string00,
      string1 = value1 + "",
      interpolate0;
  return function() {
    var string0 = this.getAttributeNS(fullname.space, fullname.local);
    return string0 === string1 ? null
        : string0 === string00 ? interpolate0
        : interpolate0 = interpolate(string00 = string0, value1);
  };
}

function attrFunction(name, interpolate, value) {
  var string00,
      string10,
      interpolate0;
  return function() {
    var string0, value1 = value(this), string1;
    if (value1 == null) return void this.removeAttribute(name);
    string0 = this.getAttribute(name);
    string1 = value1 + "";
    return string0 === string1 ? null
        : string0 === string00 && string1 === string10 ? interpolate0
        : (string10 = string1, interpolate0 = interpolate(string00 = string0, value1));
  };
}

function attrFunctionNS(fullname, interpolate, value) {
  var string00,
      string10,
      interpolate0;
  return function() {
    var string0, value1 = value(this), string1;
    if (value1 == null) return void this.removeAttributeNS(fullname.space, fullname.local);
    string0 = this.getAttributeNS(fullname.space, fullname.local);
    string1 = value1 + "";
    return string0 === string1 ? null
        : string0 === string00 && string1 === string10 ? interpolate0
        : (string10 = string1, interpolate0 = interpolate(string00 = string0, value1));
  };
}

function transition_attr(name, value) {
  var fullname = namespace(name), i = fullname === "transform" ? interpolateTransformSvg : interpolate;
  return this.attrTween(name, typeof value === "function"
      ? (fullname.local ? attrFunctionNS : attrFunction)(fullname, i, tweenValue(this, "attr." + name, value))
      : value == null ? (fullname.local ? attrRemoveNS : attrRemove)(fullname)
      : (fullname.local ? attrConstantNS : attrConstant)(fullname, i, value));
}

function attrInterpolate(name, i) {
  return function(t) {
    this.setAttribute(name, i.call(this, t));
  };
}

function attrInterpolateNS(fullname, i) {
  return function(t) {
    this.setAttributeNS(fullname.space, fullname.local, i.call(this, t));
  };
}

function attrTweenNS(fullname, value) {
  var t0, i0;
  function tween() {
    var i = value.apply(this, arguments);
    if (i !== i0) t0 = (i0 = i) && attrInterpolateNS(fullname, i);
    return t0;
  }
  tween._value = value;
  return tween;
}

function attrTween(name, value) {
  var t0, i0;
  function tween() {
    var i = value.apply(this, arguments);
    if (i !== i0) t0 = (i0 = i) && attrInterpolate(name, i);
    return t0;
  }
  tween._value = value;
  return tween;
}

function transition_attrTween(name, value) {
  var key = "attr." + name;
  if (arguments.length < 2) return (key = this.tween(key)) && key._value;
  if (value == null) return this.tween(key, null);
  if (typeof value !== "function") throw new Error;
  var fullname = namespace(name);
  return this.tween(key, (fullname.local ? attrTweenNS : attrTween)(fullname, value));
}

function delayFunction(id, value) {
  return function() {
    init(this, id).delay = +value.apply(this, arguments);
  };
}

function delayConstant(id, value) {
  return value = +value, function() {
    init(this, id).delay = value;
  };
}

function transition_delay(value) {
  var id = this._id;

  return arguments.length
      ? this.each((typeof value === "function"
          ? delayFunction
          : delayConstant)(id, value))
      : get(this.node(), id).delay;
}

function durationFunction(id, value) {
  return function() {
    set(this, id).duration = +value.apply(this, arguments);
  };
}

function durationConstant(id, value) {
  return value = +value, function() {
    set(this, id).duration = value;
  };
}

function transition_duration(value) {
  var id = this._id;

  return arguments.length
      ? this.each((typeof value === "function"
          ? durationFunction
          : durationConstant)(id, value))
      : get(this.node(), id).duration;
}

function easeConstant(id, value) {
  if (typeof value !== "function") throw new Error;
  return function() {
    set(this, id).ease = value;
  };
}

function transition_ease(value) {
  var id = this._id;

  return arguments.length
      ? this.each(easeConstant(id, value))
      : get(this.node(), id).ease;
}

function easeVarying(id, value) {
  return function() {
    var v = value.apply(this, arguments);
    if (typeof v !== "function") throw new Error;
    set(this, id).ease = v;
  };
}

function transition_easeVarying(value) {
  if (typeof value !== "function") throw new Error;
  return this.each(easeVarying(this._id, value));
}

function transition_filter(match) {
  if (typeof match !== "function") match = matcher(match);

  for (var groups = this._groups, m = groups.length, subgroups = new Array(m), j = 0; j < m; ++j) {
    for (var group = groups[j], n = group.length, subgroup = subgroups[j] = [], node, i = 0; i < n; ++i) {
      if ((node = group[i]) && match.call(node, node.__data__, i, group)) {
        subgroup.push(node);
      }
    }
  }

  return new Transition(subgroups, this._parents, this._name, this._id);
}

function transition_merge(transition) {
  if (transition._id !== this._id) throw new Error;

  for (var groups0 = this._groups, groups1 = transition._groups, m0 = groups0.length, m1 = groups1.length, m = Math.min(m0, m1), merges = new Array(m0), j = 0; j < m; ++j) {
    for (var group0 = groups0[j], group1 = groups1[j], n = group0.length, merge = merges[j] = new Array(n), node, i = 0; i < n; ++i) {
      if (node = group0[i] || group1[i]) {
        merge[i] = node;
      }
    }
  }

  for (; j < m0; ++j) {
    merges[j] = groups0[j];
  }

  return new Transition(merges, this._parents, this._name, this._id);
}

function start(name) {
  return (name + "").trim().split(/^|\s+/).every(function(t) {
    var i = t.indexOf(".");
    if (i >= 0) t = t.slice(0, i);
    return !t || t === "start";
  });
}

function onFunction(id, name, listener) {
  var on0, on1, sit = start(name) ? init : set;
  return function() {
    var schedule = sit(this, id),
        on = schedule.on;

    // If this node shared a dispatch with the previous node,
    // just assign the updated shared dispatch and we’re done!
    // Otherwise, copy-on-write.
    if (on !== on0) (on1 = (on0 = on).copy()).on(name, listener);

    schedule.on = on1;
  };
}

function transition_on(name, listener) {
  var id = this._id;

  return arguments.length < 2
      ? get(this.node(), id).on.on(name)
      : this.each(onFunction(id, name, listener));
}

function removeFunction(id) {
  return function() {
    var parent = this.parentNode;
    for (var i in this.__transition) if (+i !== id) return;
    if (parent) parent.removeChild(this);
  };
}

function transition_remove() {
  return this.on("end.remove", removeFunction(this._id));
}

function transition_select(select) {
  var name = this._name,
      id = this._id;

  if (typeof select !== "function") select = selector(select);

  for (var groups = this._groups, m = groups.length, subgroups = new Array(m), j = 0; j < m; ++j) {
    for (var group = groups[j], n = group.length, subgroup = subgroups[j] = new Array(n), node, subnode, i = 0; i < n; ++i) {
      if ((node = group[i]) && (subnode = select.call(node, node.__data__, i, group))) {
        if ("__data__" in node) subnode.__data__ = node.__data__;
        subgroup[i] = subnode;
        schedule(subgroup[i], name, id, i, subgroup, get(node, id));
      }
    }
  }

  return new Transition(subgroups, this._parents, name, id);
}

function transition_selectAll(select) {
  var name = this._name,
      id = this._id;

  if (typeof select !== "function") select = selectorAll(select);

  for (var groups = this._groups, m = groups.length, subgroups = [], parents = [], j = 0; j < m; ++j) {
    for (var group = groups[j], n = group.length, node, i = 0; i < n; ++i) {
      if (node = group[i]) {
        for (var children = select.call(node, node.__data__, i, group), child, inherit = get(node, id), k = 0, l = children.length; k < l; ++k) {
          if (child = children[k]) {
            schedule(child, name, id, k, children, inherit);
          }
        }
        subgroups.push(children);
        parents.push(node);
      }
    }
  }

  return new Transition(subgroups, parents, name, id);
}

var Selection = selection.prototype.constructor;

function transition_selection() {
  return new Selection(this._groups, this._parents);
}

function styleNull(name, interpolate) {
  var string00,
      string10,
      interpolate0;
  return function() {
    var string0 = styleValue(this, name),
        string1 = (this.style.removeProperty(name), styleValue(this, name));
    return string0 === string1 ? null
        : string0 === string00 && string1 === string10 ? interpolate0
        : interpolate0 = interpolate(string00 = string0, string10 = string1);
  };
}

function styleRemove(name) {
  return function() {
    this.style.removeProperty(name);
  };
}

function styleConstant(name, interpolate, value1) {
  var string00,
      string1 = value1 + "",
      interpolate0;
  return function() {
    var string0 = styleValue(this, name);
    return string0 === string1 ? null
        : string0 === string00 ? interpolate0
        : interpolate0 = interpolate(string00 = string0, value1);
  };
}

function styleFunction(name, interpolate, value) {
  var string00,
      string10,
      interpolate0;
  return function() {
    var string0 = styleValue(this, name),
        value1 = value(this),
        string1 = value1 + "";
    if (value1 == null) string1 = value1 = (this.style.removeProperty(name), styleValue(this, name));
    return string0 === string1 ? null
        : string0 === string00 && string1 === string10 ? interpolate0
        : (string10 = string1, interpolate0 = interpolate(string00 = string0, value1));
  };
}

function styleMaybeRemove(id, name) {
  var on0, on1, listener0, key = "style." + name, event = "end." + key, remove;
  return function() {
    var schedule = set(this, id),
        on = schedule.on,
        listener = schedule.value[key] == null ? remove || (remove = styleRemove(name)) : undefined;

    // If this node shared a dispatch with the previous node,
    // just assign the updated shared dispatch and we’re done!
    // Otherwise, copy-on-write.
    if (on !== on0 || listener0 !== listener) (on1 = (on0 = on).copy()).on(event, listener0 = listener);

    schedule.on = on1;
  };
}

function transition_style(name, value, priority) {
  var i = (name += "") === "transform" ? interpolateTransformCss : interpolate;
  return value == null ? this
      .styleTween(name, styleNull(name, i))
      .on("end.style." + name, styleRemove(name))
    : typeof value === "function" ? this
      .styleTween(name, styleFunction(name, i, tweenValue(this, "style." + name, value)))
      .each(styleMaybeRemove(this._id, name))
    : this
      .styleTween(name, styleConstant(name, i, value), priority)
      .on("end.style." + name, null);
}

function styleInterpolate(name, i, priority) {
  return function(t) {
    this.style.setProperty(name, i.call(this, t), priority);
  };
}

function styleTween(name, value, priority) {
  var t, i0;
  function tween() {
    var i = value.apply(this, arguments);
    if (i !== i0) t = (i0 = i) && styleInterpolate(name, i, priority);
    return t;
  }
  tween._value = value;
  return tween;
}

function transition_styleTween(name, value, priority) {
  var key = "style." + (name += "");
  if (arguments.length < 2) return (key = this.tween(key)) && key._value;
  if (value == null) return this.tween(key, null);
  if (typeof value !== "function") throw new Error;
  return this.tween(key, styleTween(name, value, priority == null ? "" : priority));
}

function textConstant(value) {
  return function() {
    this.textContent = value;
  };
}

function textFunction(value) {
  return function() {
    var value1 = value(this);
    this.textContent = value1 == null ? "" : value1;
  };
}

function transition_text(value) {
  return this.tween("text", typeof value === "function"
      ? textFunction(tweenValue(this, "text", value))
      : textConstant(value == null ? "" : value + ""));
}

function textInterpolate(i) {
  return function(t) {
    this.textContent = i.call(this, t);
  };
}

function textTween(value) {
  var t0, i0;
  function tween() {
    var i = value.apply(this, arguments);
    if (i !== i0) t0 = (i0 = i) && textInterpolate(i);
    return t0;
  }
  tween._value = value;
  return tween;
}

function transition_textTween(value) {
  var key = "text";
  if (arguments.length < 1) return (key = this.tween(key)) && key._value;
  if (value == null) return this.tween(key, null);
  if (typeof value !== "function") throw new Error;
  return this.tween(key, textTween(value));
}

function transition_transition() {
  var name = this._name,
      id0 = this._id,
      id1 = newId();

  for (var groups = this._groups, m = groups.length, j = 0; j < m; ++j) {
    for (var group = groups[j], n = group.length, node, i = 0; i < n; ++i) {
      if (node = group[i]) {
        var inherit = get(node, id0);
        schedule(node, name, id1, i, group, {
          time: inherit.time + inherit.delay + inherit.duration,
          delay: 0,
          duration: inherit.duration,
          ease: inherit.ease
        });
      }
    }
  }

  return new Transition(groups, this._parents, name, id1);
}

function transition_end() {
  var on0, on1, that = this, id = that._id, size = that.size();
  return new Promise(function(resolve, reject) {
    var cancel = {value: reject},
        end = {value: function() { if (--size === 0) resolve(); }};

    that.each(function() {
      var schedule = set(this, id),
          on = schedule.on;

      // If this node shared a dispatch with the previous node,
      // just assign the updated shared dispatch and we’re done!
      // Otherwise, copy-on-write.
      if (on !== on0) {
        on1 = (on0 = on).copy();
        on1._.cancel.push(cancel);
        on1._.interrupt.push(cancel);
        on1._.end.push(end);
      }

      schedule.on = on1;
    });

    // The selection was empty, resolve end immediately
    if (size === 0) resolve();
  });
}

var id = 0;

function Transition(groups, parents, name, id) {
  this._groups = groups;
  this._parents = parents;
  this._name = name;
  this._id = id;
}

function transition(name) {
  return selection().transition(name);
}

function newId() {
  return ++id;
}

var selection_prototype = selection.prototype;

Transition.prototype = transition.prototype = {
  constructor: Transition,
  select: transition_select,
  selectAll: transition_selectAll,
  selectChild: selection_prototype.selectChild,
  selectChildren: selection_prototype.selectChildren,
  filter: transition_filter,
  merge: transition_merge,
  selection: transition_selection,
  transition: transition_transition,
  call: selection_prototype.call,
  nodes: selection_prototype.nodes,
  node: selection_prototype.node,
  size: selection_prototype.size,
  empty: selection_prototype.empty,
  each: selection_prototype.each,
  on: transition_on,
  attr: transition_attr,
  attrTween: transition_attrTween,
  style: transition_style,
  styleTween: transition_styleTween,
  text: transition_text,
  textTween: transition_textTween,
  remove: transition_remove,
  tween: transition_tween,
  delay: transition_delay,
  duration: transition_duration,
  ease: transition_ease,
  easeVarying: transition_easeVarying,
  end: transition_end,
  [Symbol.iterator]: selection_prototype[Symbol.iterator]
};

function cubicInOut(t) {
  return ((t *= 2) <= 1 ? t * t * t : (t -= 2) * t * t + 2) / 2;
}

var defaultTiming = {
  time: null, // Set on use.
  delay: 0,
  duration: 250,
  ease: cubicInOut
};

function inherit(node, id) {
  var timing;
  while (!(timing = node.__transition) || !(timing = timing[id])) {
    if (!(node = node.parentNode)) {
      throw new Error(`transition ${id} not found`);
    }
  }
  return timing;
}

function selection_transition(name) {
  var id,
      timing;

  if (name instanceof Transition) {
    id = name._id, name = name._name;
  } else {
    id = newId(), (timing = defaultTiming).time = now(), name = name == null ? null : name + "";
  }

  for (var groups = this._groups, m = groups.length, j = 0; j < m; ++j) {
    for (var group = groups[j], n = group.length, node, i = 0; i < n; ++i) {
      if (node = group[i]) {
        schedule(node, name, id, i, group, timing || inherit(node, id));
      }
    }
  }

  return new Transition(groups, this._parents, name, id);
}

selection.prototype.interrupt = selection_interrupt;
selection.prototype.transition = selection_transition;

var root = [null];

function active(node, name) {
  var schedules = node.__transition,
      schedule,
      i;

  if (schedules) {
    name = name == null ? null : name + "";
    for (i in schedules) {
      if ((schedule = schedules[i]).state > SCHEDULED && schedule.name === name) {
        return new Transition([[node]], root, name, +i);
      }
    }
  }

  return null;
}

export { active, arc, chord, chordDirected, chordTranspose, color, create$1 as create, creator, cubehelix, drag, nodrag as dragDisable, yesdrag as dragEnable, gray, hcl, hsl, interrupt, formatIso as isoFormat, parseIso as isoParse, lab, lch, local, matcher, namespace, namespaces, pointer, pointers, rgb, ribbon$1 as ribbon, ribbonArrow, band as scaleBand, diverging as scaleDiverging, divergingLog as scaleDivergingLog, divergingPow as scaleDivergingPow, divergingSqrt as scaleDivergingSqrt, divergingSymlog as scaleDivergingSymlog, identity as scaleIdentity, implicit as scaleImplicit, linear as scaleLinear, log as scaleLog, ordinal as scaleOrdinal, point as scalePoint, pow as scalePow, quantile as scaleQuantile, quantize as scaleQuantize, radial as scaleRadial, sequential as scaleSequential, sequentialLog as scaleSequentialLog, sequentialPow as scaleSequentialPow, sequentialQuantile as scaleSequentialQuantile, sequentialSqrt as scaleSequentialSqrt, sequentialSymlog as scaleSequentialSymlog, sqrt$1 as scaleSqrt, symlog as scaleSymlog, threshold as scaleThreshold, time as scaleTime, utcTime as scaleUtc, select, selectAll, selection, selector, selectorAll, styleValue as style, tickFormat, timeFormat, defaultLocale as timeFormatDefaultLocale, formatLocale as timeFormatLocale, timeParse, transition, utcFormat, utcParse, version, defaultView as window };
