jsroot/modules/d3.mjs

JavaScript ROOT

// 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 te