d3/dist/d3.js

Data-Driven Documents

// https://d3js.org v7.0.0 Copyright 2010-2021 Mike Bostock
(function (global, factory) {
typeof exports === 'object' && typeof module !== 'undefined' ? factory(exports) :
typeof define === 'function' && define.amd ? define(['exports'], factory) :
(global = typeof globalThis !== 'undefined' ? globalThis : global || self, factory(global.d3 = global.d3 || {}));
}(this, (function (exports) { 'use strict';

var version = "7.0.0";

function ascending$3(a, b) {
  return a == null || b == null ? NaN
    : a < b ? -1
    : a > b ? 1
    : a >= b ? 0
    : NaN;
}

function bisector(f) {
  let delta = f;
  let compare = f;

  if (f.length === 1) {
    delta = (d, x) => f(d) - x;
    compare = ascendingComparator(f);
  }

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

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

  function center(a, x, lo, hi) {
    if (lo == null) lo = 0;
    if (hi == null) 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 ascendingComparator(f) {
  return (d, x) => ascending$3(f(d), x);
}

function number$3(x) {
  return x === null ? NaN : +x;
}

function* numbers(values, valueof) {
  if (valueof === undefined) {
    for (let value of values) {
      if (value != null && (value = +value) >= value) {
        yield value;
      }
    }
  } else {
    let index = -1;
    for (let value of values) {
      if ((value = valueof(value, ++index, values)) != null && (value = +value) >= value) {
        yield value;
      }
    }
  }
}

const ascendingBisect = bisector(ascending$3);
const bisectRight = ascendingBisect.right;
const bisectLeft = ascendingBisect.left;
const bisectCenter = bisector(number$3).center;

function count$1(values, valueof) {
  let count = 0;
  if (valueof === undefined) {
    for (let value of values) {
      if (value != null && (value = +value) >= value) {
        ++count;
      }
    }
  } else {
    let index = -1;
    for (let value of values) {
      if ((value = valueof(value, ++index, values)) != null && (value = +value) >= value) {
        ++count;
      }
    }
  }
  return count;
}

function length$3(array) {
  return array.length | 0;
}

function empty$2(length) {
  return !(length > 0);
}

function arrayify(values) {
  return typeof values !== "object" || "length" in values ? values : Array.from(values);
}

function reducer(reduce) {
  return values => reduce(...values);
}

function cross$2(...values) {
  const reduce = typeof values[values.length - 1] === "function" && reducer(values.pop());
  values = values.map(arrayify);
  const lengths = values.map(length$3);
  const j = values.length - 1;
  const index = new Array(j + 1).fill(0);
  const product = [];
  if (j < 0 || lengths.some(empty$2)) return product;
  while (true) {
    product.push(index.map((j, i) => values[i][j]));
    let i = j;
    while (++index[i] === lengths[i]) {
      if (i === 0) return reduce ? product.map(reduce) : product;
      index[i--] = 0;
    }
  }
}

function cumsum(values, valueof) {
  var sum = 0, index = 0;
  return Float64Array.from(values, valueof === undefined
    ? v => (sum += +v || 0)
    : v => (sum += +valueof(v, index++, values) || 0));
}

function descending$2(a, b) {
  return a == null || b == null ? NaN
    : b < a ? -1
    : b > a ? 1
    : b >= a ? 0
    : NaN;
}

function variance(values, valueof) {
  let count = 0;
  let delta;
  let mean = 0;
  let sum = 0;
  if (valueof === undefined) {
    for (let value of values) {
      if (value != null && (value = +value) >= value) {
        delta = value - mean;
        mean += delta / ++count;
        sum += delta * (value - mean);
      }
    }
  } else {
    let index = -1;
    for (let value of values) {
      if ((value = valueof(value, ++index, values)) != null && (value = +value) >= value) {
        delta = value - mean;
        mean += delta / ++count;
        sum += delta * (value - mean);
      }
    }
  }
  if (count > 1) return sum / (count - 1);
}

function deviation(values, valueof) {
  const v = variance(values, valueof);
  return v ? Math.sqrt(v) : v;
}

function extent$1(values, valueof) {
  let min;
  let max;
  if (valueof === undefined) {
    for (const value of values) {
      if (value != null) {
        if (min === undefined) {
          if (value >= value) min = max = value;
        } else {
          if (min > value) min = value;
          if (max < value) max = value;
        }
      }
    }
  } else {
    let index = -1;
    for (let value of values) {
      if ((value = valueof(value, ++index, values)) != null) {
        if (min === undefined) {
          if (value >= value) min = max = value;
        } else {
          if (min > value) min = value;
          if (max < value) max = value;
        }
      }
    }
  }
  return [min, max];
}

// https://github.com/python/cpython/blob/a74eea238f5baba15797e2e8b570d153bc8690a7/Modules/mathmodule.c#L1423
class Adder {
  constructor() {
    this._partials = new Float64Array(32);
    this._n = 0;
  }
  add(x) {
    const p = this._partials;
    let i = 0;
    for (let j = 0; j < this._n && j < 32; j++) {
      const y = p[j],
        hi = x + y,
        lo = Math.abs(x) < Math.abs(y) ? x - (hi - y) : y - (hi - x);
      if (lo) p[i++] = lo;
      x = hi;
    }
    p[i] = x;
    this._n = i + 1;
    return this;
  }
  valueOf() {
    const p = this._partials;
    let n = this._n, x, y, lo, hi = 0;
    if (n > 0) {
      hi = p[--n];
      while (n > 0) {
        x = hi;
        y = p[--n];
        hi = x + y;
        lo = y - (hi - x);
        if (lo) break;
      }
      if (n > 0 && ((lo < 0 && p[n - 1] < 0) || (lo > 0 && p[n - 1] > 0))) {
        y = lo * 2;
        x = hi + y;
        if (y == x - hi) hi = x;
      }
    }
    return hi;
  }
}

function fsum(values, valueof) {
  const adder = new Adder();
  if (valueof === undefined) {
    for (let value of values) {
      if (value = +value) {
        adder.add(value);
      }
    }
  } else {
    let index = -1;
    for (let value of values) {
      if (value = +valueof(value, ++index, values)) {
        adder.add(value);
      }
    }
  }
  return +adder;
}

function fcumsum(values, valueof) {
  const adder = new Adder();
  let index = -1;
  return Float64Array.from(values, valueof === undefined
      ? v => adder.add(+v || 0)
      : v => adder.add(+valueof(v, ++index, values) || 0)
  );
}

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));
  }
}

class InternSet extends Set {
  constructor(values, key = keyof) {
    super();
    Object.defineProperties(this, {_intern: {value: new Map()}, _key: {value: key}});
    if (values != null) for (const value of values) this.add(value);
  }
  has(value) {
    return super.has(intern_get(this, value));
  }
  add(value) {
    return super.add(intern_set(this, value));
  }
  delete(value) {
    return super.delete(intern_delete(this, value));
  }
}

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(value);
    _intern.delete(key);
  }
  return value;
}

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

function identity$9(x) {
  return x;
}

function group(values, ...keys) {
  return nest(values, identity$9, identity$9, keys);
}

function groups(values, ...keys) {
  return nest(values, Array.from, identity$9, keys);
}

function flatten$1(groups, keys) {
  for (let i = 1, n = keys.length; i < n; ++i) {
    groups = groups.flatMap(g => g.pop().map(([key, value]) => [...g, key, value]));
  }
  return groups;
}

function flatGroup(values, ...keys) {
  return flatten$1(groups(values, ...keys), keys);
}

function flatRollup(values, reduce, ...keys) {
  return flatten$1(rollups(values, reduce, ...keys), keys);
}

function rollup(values, reduce, ...keys) {
  return nest(values, identity$9, reduce, keys);
}

function rollups(values, reduce, ...keys) {
  return nest(values, Array.from, reduce, keys);
}

function index$4(values, ...keys) {
  return nest(values, identity$9, unique, keys);
}

function indexes(values, ...keys) {
  return nest(values, Array.from, unique, keys);
}

function unique(values) {
  if (values.length !== 1) throw new Error("duplicate key");
  return values[0];
}

function nest(values, map, reduce, keys) {
  return (function regroup(values, i) {
    if (i >= keys.length) return reduce(values);
    const groups = new InternMap();
    const keyof = keys[i++];
    let index = -1;
    for (const value of values) {
      const key = keyof(value, ++index, values);
      const group = groups.get(key);
      if (group) group.push(value);
      else groups.set(key, [value]);
    }
    for (const [key, values] of groups) {
      groups.set(key, regroup(values, i));
    }
    return map(groups);
  })(values, 0);
}

function permute(source, keys) {
  return Array.from(keys, key => source[key]);
}

function sort(values, ...F) {
  if (typeof values[Symbol.iterator] !== "function") throw new TypeError("values is not iterable");
  values = Array.from(values);
  let [f = ascending$3] = F;
  if (f.length === 1 || F.length > 1) {
    const index = Uint32Array.from(values, (d, i) => i);
    if (F.length > 1) {
      F = F.map(f => values.map(f));
      index.sort((i, j) => {
        for (const f of F) {
          const c = ascending$3(f[i], f[j]);
          if (c) return c;
        }
      });
    } else {
      f = values.map(f);
      index.sort((i, j) => ascending$3(f[i], f[j]));
    }
    return permute(values, index);
  }
  return values.sort(f);
}

function groupSort(values, reduce, key) {
  return (reduce.length === 1
    ? sort(rollup(values, reduce, key), (([ak, av], [bk, bv]) => ascending$3(av, bv) || ascending$3(ak, bk)))
    : sort(group(values, key), (([ak, av], [bk, bv]) => reduce(av, bv) || ascending$3(ak, bk))))
    .map(([key]) => key);
}

var array$5 = Array.prototype;

var slice$3 = array$5.slice;

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

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

function ticks(start, stop, count) {
  var reverse,
      i = -1,
      n,
      ticks,
      step;

  stop = +stop, start = +start, count = +count;
  if (start === stop && count > 0) return [start];
  if (reverse = stop < start) n = start, start = stop, stop = n;
  if ((step = tickIncrement(start, stop, count)) === 0 || !isFinite(step)) return [];

  if (step > 0) {
    let r0 = Math.round(start / step), r1 = Math.round(stop / step);
    if (r0 * step < start) ++r0;
    if (r1 * step > stop) --r1;
    ticks = new Array(n = r1 - r0 + 1);
    while (++i < n) ticks[i] = (r0 + i) * step;
  } else {
    step = -step;
    let r0 = Math.round(start * step), r1 = Math.round(stop * step);
    if (r0 / step < start) ++r0;
    if (r1 / step > stop) --r1;
    ticks = new Array(n = r1 - r0 + 1);
    while (++i < n) ticks[i] = (r0 + i) / step;
  }

  if (reverse) ticks.reverse();

  return ticks;
}

function tickIncrement(start, stop, count) {
  var step = (stop - start) / Math.max(0, count),
      power = Math.floor(Math.log(step) / Math.LN10),
      error = step / Math.pow(10, power);
  return power >= 0
      ? (error >= e10 ? 10 : error >= e5 ? 5 : error >= e2 ? 2 : 1) * Math.pow(10, power)
      : -Math.pow(10, -power) / (error >= e10 ? 10 : error >= e5 ? 5 : error >= e2 ? 2 : 1);
}

function tickStep(start, stop, count) {
  var step0 = Math.abs(stop - start) / Math.max(0, count),
      step1 = Math.pow(10, Math.floor(Math.log(step0) / Math.LN10)),
      error = step0 / step1;
  if (error >= e10) step1 *= 10;
  else if (error >= e5) step1 *= 5;
  else if (error >= e2) step1 *= 2;
  return stop < start ? -step1 : step1;
}

function nice$1(start, stop, count) {
  let prestep;
  while (true) {
    const step = tickIncrement(start, stop, count);
    if (step === prestep || step === 0 || !isFinite(step)) {
      return [start, stop];
    } 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;
    }
    prestep = step;
  }
}

function thresholdSturges(values) {
  return Math.ceil(Math.log(count$1(values)) / Math.LN2) + 1;
}

function bin() {
  var value = identity$9,
      domain = extent$1,
      threshold = thresholdSturges;

  function histogram(data) {
    if (!Array.isArray(data)) data = Array.from(data);

    var i,
        n = data.length,
        x,
        values = new Array(n);

    for (i = 0; i < n; ++i) {
      values[i] = value(data[i], i, data);
    }

    var xz = domain(values),
        x0 = xz[0],
        x1 = xz[1],
        tz = threshold(values, x0, x1);

    // Convert number of thresholds into uniform thresholds, and nice the
    // default domain accordingly.
    if (!Array.isArray(tz)) {
      const max = x1, tn = +tz;
      if (domain === extent$1) [x0, x1] = nice$1(x0, x1, tn);
      tz = ticks(x0, x1, tn);

      // If the last threshold is coincident with the domain’s upper bound, the
      // last bin will be zero-width. If the default domain is used, and this
      // last threshold is coincident with the maximum input value, we can
      // extend the niced upper bound by one tick to ensure uniform bin widths;
      // otherwise, we simply remove the last threshold. Note that we don’t
      // coerce values or the domain to numbers, and thus must be careful to
      // compare order (>=) rather than strict equality (===)!
      if (tz[tz.length - 1] >= x1) {
        if (max >= x1 && domain === extent$1) {
          const step = tickIncrement(x0, x1, tn);
          if (isFinite(step)) {
            if (step > 0) {
              x1 = (Math.floor(x1 / step) + 1) * step;
            } else if (step < 0) {
              x1 = (Math.ceil(x1 * -step) + 1) / -step;
            }
          }
        } else {
          tz.pop();
        }
      }
    }

    // Remove any thresholds outside the domain.
    var m = tz.length;
    while (tz[0] <= x0) tz.shift(), --m;
    while (tz[m - 1] > x1) tz.pop(), --m;

    var bins = new Array(m + 1),
        bin;

    // Initialize bins.
    for (i = 0; i <= m; ++i) {
      bin = bins[i] = [];
      bin.x0 = i > 0 ? tz[i - 1] : x0;
      bin.x1 = i < m ? tz[i] : x1;
    }

    // Assign data to bins by value, ignoring any outside the domain.
    for (i = 0; i < n; ++i) {
      x = values[i];
      if (x != null && x0 <= x && x <= x1) {
        bins[bisectRight(tz, x, 0, m)].push(data[i]);
      }
    }

    return bins;
  }

  histogram.value = function(_) {
    return arguments.length ? (value = typeof _ === "function" ? _ : constant$b(_), histogram) : value;
  };

  histogram.domain = function(_) {
    return arguments.length ? (domain = typeof _ === "function" ? _ : constant$b([_[0], _[1]]), histogram) : domain;
  };

  histogram.thresholds = function(_) {
    return arguments.length ? (threshold = typeof _ === "function" ? _ : Array.isArray(_) ? constant$b(slice$3.call(_)) : constant$b(_), histogram) : threshold;
  };

  return histogram;
}

function max$3(values, valueof) {
  let max;
  if (valueof === undefined) {
    for (const value of values) {
      if (value != null
          && (max < value || (max === undefined && value >= value))) {
        max = value;
      }
    }
  } else {
    let index = -1;
    for (let value of values) {
      if ((value = valueof(value, ++index, values)) != null
          && (max < value || (max === undefined && value >= value))) {
        max = value;
      }
    }
  }
  return max;
}

function min$2(values, valueof) {
  let min;
  if (valueof === undefined) {
    for (const value of values) {
      if (value != null
          && (min > value || (min === undefined && value >= value))) {
        min = value;
      }
    }
  } else {
    let index = -1;
    for (let value of values) {
      if ((value = valueof(value, ++index, values)) != 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 = array.length - 1, compare = ascending$3) {
  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$1(array, left, k);
    if (compare(array[right], t) > 0) swap$1(array, left, right);

    while (i < j) {
      swap$1(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$1(array, left, j);
    else ++j, swap$1(array, j, right);

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

function swap$1(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, valueof));
  if (!(n = values.length)) return;
  if ((p = +p) <= 0 || n < 2) return min$2(values);
  if (p >= 1) return max$3(values);
  var n,
      i = (n - 1) * p,
      i0 = Math.floor(i),
      value0 = max$3(quickselect(values, i0).subarray(0, i0 + 1)),
      value1 = min$2(values.subarray(i0 + 1));
  return value0 + (value1 - value0) * (i - i0);
}

function quantileSorted(values, p, valueof = number$3) {
  if (!(n = values.length)) return;
  if ((p = +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 freedmanDiaconis(values, min, max) {
  return Math.ceil((max - min) / (2 * (quantile$1(values, 0.75) - quantile$1(values, 0.25)) * Math.pow(count$1(values), -1 / 3)));
}

function scott(values, min, max) {
  return Math.ceil((max - min) / (3.5 * deviation(values) * Math.pow(count$1(values), -1 / 3)));
}

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

function mean(values, valueof) {
  let count = 0;
  let sum = 0;
  if (valueof === undefined) {
    for (let value of values) {
      if (value != null && (value = +value) >= value) {
        ++count, sum += value;
      }
    }
  } else {
    let index = -1;
    for (let value of values) {
      if ((value = valueof(value, ++index, values)) != null && (value = +value) >= value) {
        ++count, sum += value;
      }
    }
  }
  if (count) return sum / count;
}

function median(values, valueof) {
  return quantile$1(values, 0.5, valueof);
}

function* flatten(arrays) {
  for (const array of arrays) {
    yield* array;
  }
}

function merge(arrays) {
  return Array.from(flatten(arrays));
}

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

function mode(values, valueof) {
  const counts = new InternMap();
  if (valueof === undefined) {
    for (let value of values) {
      if (value != null && value >= value) {
        counts.set(value, (counts.get(value) || 0) + 1);
      }
    }
  } else {
    let index = -1;
    for (let value of values) {
      if ((value = valueof(value, ++index, values)) != null && value >= value) {
        counts.set(value, (counts.get(value) || 0) + 1);
      }
    }
  }
  let modeValue;
  let modeCount = 0;
  for (const [value, count] of counts) {
    if (count > modeCount) {
      modeCount = count;
      modeValue = value;
    }
  }
  return modeValue;
}

function pairs(values, pairof = pair) {
  const pairs = [];
  let previous;
  let first = false;
  for (const value of values) {
    if (first) pairs.push(pairof(previous, value));
    previous = value;
    first = true;
  }
  return pairs;
}

function pair(a, b) {
  return [a, b];
}

function sequence(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 least(values, compare = ascending$3) {
  let min;
  let defined = false;
  if (compare.length === 1) {
    let minValue;
    for (const element of values) {
      const value = compare(element);
      if (defined
          ? ascending$3(value, minValue) < 0
          : ascending$3(value, value) === 0) {
        min = element;
        minValue = value;
        defined = true;
      }
    }
  } else {
    for (const value of values) {
      if (defined
          ? compare(value, min) < 0
          : compare(value, value) === 0) {
        min = value;
        defined = true;
      }
    }
  }
  return min;
}

function leastIndex(values, compare = ascending$3) {
  if (compare.length === 1) return minIndex(values, compare);
  let minValue;
  let min = -1;
  let index = -1;
  for (const value of values) {
    ++index;
    if (min < 0
        ? compare(value, value) === 0
        : compare(value, minValue) < 0) {
      minValue = value;
      min = index;
    }
  }
  return min;
}

function greatest(values, compare = ascending$3) {
  let max;
  let defined = false;
  if (compare.length === 1) {
    let maxValue;
    for (const element of values) {
      const value = compare(element);
      if (defined
          ? ascending$3(value, maxValue) > 0
          : ascending$3(value, value) === 0) {
        max = element;
        maxValue = value;
        defined = true;
      }
    }
  } else {
    for (const value of values) {
      if (defined
          ? compare(value, max) > 0
          : compare(value, value) === 0) {
        max = value;
        defined = true;
      }
    }
  }
  return max;
}

function greatestIndex(values, compare = ascending$3) {
  if (compare.length === 1) return maxIndex(values, compare);
  let maxValue;
  let max = -1;
  let index = -1;
  for (const value of values) {
    ++index;
    if (max < 0
        ? compare(value, value) === 0
        : compare(value, maxValue) > 0) {
      maxValue = value;
      max = index;
    }
  }
  return max;
}

function scan(values, compare) {
  const index = leastIndex(values, compare);
  return index < 0 ? undefined : index;
}

var shuffle$1 = shuffler(Math.random);

function shuffler(random) {
  return function shuffle(array, i0 = 0, i1 = array.length) {
    let m = i1 - (i0 = +i0);
    while (m) {
      const i = random() * m-- | 0, t = array[m + i0];
      array[m + i0] = array[i + i0];
      array[i + i0] = t;
    }
    return array;
  };
}

function sum$2(values, valueof) {
  let sum = 0;
  if (valueof === undefined) {
    for (let value of values) {
      if (value = +value) {
        sum += value;
      }
    }
  } else {
    let index = -1;
    for (let value of values) {
      if (value = +valueof(value, ++index, values)) {
        sum += value;
      }
    }
  }
  return sum;
}

function transpose(matrix) {
  if (!(n = matrix.length)) return [];
  for (var i = -1, m = min$2(matrix, length$2), transpose = new Array(m); ++i < m;) {
    for (var j = -1, n, row = transpose[i] = new Array(n); ++j < n;) {
      row[j] = matrix[j][i];
    }
  }
  return transpose;
}

function length$2(d) {
  return d.length;
}

function zip() {
  return transpose(arguments);
}

function every(values, test) {
  if (typeof test !== "function") throw new TypeError("test is not a function");
  let index = -1;
  for (const value of values) {
    if (!test(value, ++index, values)) {
      return false;
    }
  }
  return true;
}

function some(values, test) {
  if (typeof test !== "function") throw new TypeError("test is not a function");
  let index = -1;
  for (const value of values) {
    if (test(value, ++index, values)) {
      return true;
    }
  }
  return false;
}

function filter$1(values, test) {
  if (typeof test !== "function") throw new TypeError("test is not a function");
  const array = [];
  let index = -1;
  for (const value of values) {
    if (test(value, ++index, values)) {
      array.push(value);
    }
  }
  return array;
}

function map$1(values, mapper) {
  if (typeof values[Symbol.iterator] !== "function") throw new TypeError("values is not iterable");
  if (typeof mapper !== "function") throw new TypeError("mapper is not a function");
  return Array.from(values, (value, index) => mapper(value, index, values));
}

function reduce(values, reducer, value) {
  if (typeof reducer !== "function") throw new TypeError("reducer is not a function");
  const iterator = values[Symbol.iterator]();
  let done, next, index = -1;
  if (arguments.length < 3) {
    ({done, value} = iterator.next());
    if (done) return;
    ++index;
  }
  while (({done, value: next} = iterator.next()), !done) {
    value = reducer(value, next, ++index, values);
  }
  return value;
}

function reverse$1(values) {
  if (typeof values[Symbol.iterator] !== "function") throw new TypeError("values is not iterable");
  return Array.from(values).reverse();
}

function difference(values, ...others) {
  values = new Set(values);
  for (const other of others) {
    for (const value of other) {
      values.delete(value);
    }
  }
  return values;
}

function disjoint(values, other) {
  const iterator = other[Symbol.iterator](), set = new Set();
  for (const v of values) {
    if (set.has(v)) return false;
    let value, done;
    while (({value, done} = iterator.next())) {
      if (done) break;
      if (Object.is(v, value)) return false;
      set.add(value);
    }
  }
  return true;
}

function set$2(values) {
  return values instanceof Set ? values : new Set(values);
}

function intersection(values, ...others) {
  values = new Set(values);
  others = others.map(set$2);
  out: for (const value of values) {
    for (const other of others) {
      if (!other.has(value)) {
        values.delete(value);
        continue out;
      }
    }
  }
  return values;
}

function superset(values, other) {
  const iterator = values[Symbol.iterator](), set = new Set();
  for (const o of other) {
    if (set.has(o)) continue;
    let value, done;
    while (({value, done} = iterator.next())) {
      if (done) return false;
      set.add(value);
      if (Object.is(o, value)) break;
    }
  }
  return true;
}

function subset(values, other) {
  return superset(other, values);
}

function union(...others) {
  const set = new Set();
  for (const other of others) {
    for (const o of other) {
      set.add(o);
    }
  }
  return set;
}

function identity$8(x) {
  return x;
}

var top = 1,
    right = 2,
    bottom = 3,
    left = 4,
    epsilon$6 = 1e-6;

function translateX(x) {
  return "translate(" + x + ",0)";
}

function translateY(y) {
  return "translate(0," + y + ")";
}

function number$2(scale) {
  return d => +scale(d);
}

function center$1(scale, offset) {
  offset = Math.max(0, scale.bandwidth() - offset * 2) / 2;
  if (scale.round()) offset = Math.round(offset);
  return d => +scale(d) + offset;
}

function entering() {
  return !this.__axis;
}

function axis(orient, scale) {
  var tickArguments = [],
      tickValues = null,
      tickFormat = null,
      tickSizeInner = 6,
      tickSizeOuter = 6,
      tickPadding = 3,
      offset = typeof window !== "undefined" && window.devicePixelRatio > 1 ? 0 : 0.5,
      k = orient === top || orient === left ? -1 : 1,
      x = orient === left || orient === right ? "x" : "y",
      transform = orient === top || orient === bottom ? translateX : translateY;

  function axis(context) {
    var values = tickValues == null ? (scale.ticks ? scale.ticks.apply(scale, tickArguments) : scale.domain()) : tickValues,
        format = tickFormat == null ? (scale.tickFormat ? scale.tickFormat.apply(scale, tickArguments) : identity$8) : tickFormat,
        spacing = Math.max(tickSizeInner, 0) + tickPadding,
        range = scale.range(),
        range0 = +range[0] + offset,
        range1 = +range[range.length - 1] + offset,
        position = (scale.bandwidth ? center$1 : number$2)(scale.copy(), offset),
        selection = context.selection ? context.selection() : context,
        path = selection.selectAll(".domain").data([null]),
        tick = selection.selectAll(".tick").data(values, scale).order(),
        tickExit = tick.exit(),
        tickEnter = tick.enter().append("g").attr("class", "tick"),
        line = tick.select("line"),
        text = tick.select("text");

    path = path.merge(path.enter().insert("path", ".tick")
        .attr("class", "domain")
        .attr("stroke", "currentColor"));

    tick = tick.merge(tickEnter);

    line = line.merge(tickEnter.append("line")
        .attr("stroke", "currentColor")
        .attr(x + "2", k * tickSizeInner));

    text = text.merge(tickEnter.append("text")
        .attr("fill", "currentColor")
        .attr(x, k * spacing)
        .attr("dy", orient === top ? "0em" : orient === bottom ? "0.71em" : "0.32em"));

    if (context !== selection) {
      path = path.transition(context);
      tick = tick.transition(context);
      line = line.transition(context);
      text = text.transition(context);

      tickExit = tickExit.transition(context)
          .attr("opacity", epsilon$6)
          .attr("transform", function(d) { return isFinite(d = position(d)) ? transform(d + offset) : this.getAttribute("transform"); });

      tickEnter
          .attr("opacity", epsilon$6)
          .attr("transform", function(d) { var p = this.parentNode.__axis; return transform((p && isFinite(p = p(d)) ? p : position(d)) + offset); });
    }

    tickExit.remove();

    path
        .attr("d", orient === left || orient === right
            ? (tickSizeOuter ? "M" + k * tickSizeOuter + "," + range0 + "H" + offset + "V" + range1 + "H" + k * tickSizeOuter : "M" + offset + "," + range0 + "V" + range1)
            : (tickSizeOuter ? "M" + range0 + "," + k * tickSizeOuter + "V" + offset + "H" + range1 + "V" + k * tickSizeOuter : "M" + range0 + "," + offset + "H" + range1));

    tick
        .attr("opacity", 1)
        .attr("transform", function(d) { return transform(position(d) + offset); });

    line
        .attr(x + "2", k * tickSizeInner);

    text
        .attr(x, k * spacing)
        .text(format);

    selection.filter(entering)
        .attr("fill", "none")
        .attr("font-size", 10)
        .attr("font-family", "sans-serif")
        .attr("text-anchor", orient === right ? "start" : orient === left ? "end" : "middle");

    selection
        .each(function() { this.__axis = position; });
  }

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

  axis.ticks = function() {
    return tickArguments = Array.from(arguments), axis;
  };

  axis.tickArguments = function(_) {
    return arguments.length ? (tickArguments = _ == null ? [] : Array.from(_), axis) : tickArguments.slice();
  };

  axis.tickValues = function(_) {
    return arguments.length ? (tickValues = _ == null ? null : Array.from(_), axis) : tickValues && tickValues.slice();
  };

  axis.tickFormat = function(_) {
    return arguments.length ? (tickFormat = _, axis) : tickFormat;
  };

  axis.tickSize = function(_) {
    return arguments.length ? (tickSizeInner = tickSizeOuter = +_, axis) : tickSizeInner;
  };

  axis.tickSizeInner = function(_) {
    return arguments.length ? (tickSizeInner = +_, axis) : tickSizeInner;
  };

  axis.tickSizeOuter = function(_) {
    return arguments.length ? (tickSizeOuter = +_, axis) : tickSizeOuter;
  };

  axis.tickPadding = function(_) {
    return arguments.length ? (tickPadding = +_, axis) : tickPadding;
  };

  axis.offset = function(_) {
    return arguments.length ? (offset = +_, axis) : offset;
  };

  return axis;
}

function axisTop(scale) {
  return axis(top, scale);
}

function axisRight(scale) {
  return axis(right, scale);
}

function axisBottom(scale) {
  return axis(bottom, scale);
}

function axisLeft(scale) {
  return axis(left, scale);
}

var noop$3 = {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$3, 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$2() {}

function selector(selector) {
  return selector == null ? none$2 : 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$4(x) {
  return x == null ? [] : Array.isArray(x) ? x : Array.from(x);
}

function empty$1() {
  return [];
}

function selectorAll(selector) {
  return selector == null ? empty$1 : function() {
    return this.querySelectorAll(selector);
  };
}

function arrayAll(select) {
  return function() {
    return array$4(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$1 = Array.prototype.find;

function childFind(match) {
  return function() {
    return find$1.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$a(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$a(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$2;

  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$2(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(callbac