d3-force-magnetic/dist/d3-force-magnetic.js

A natural attraction/repulsion force type for the d3-force simulation engine.

// Version 1.0.4 d3-force-magnetic - https://github.com/vasturiano/d3-force-magnetic
(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';

  function _typeof(o) {
    "@babel/helpers - typeof";

    return _typeof = "function" == typeof Symbol && "symbol" == typeof Symbol.iterator ? function (o) {
      return typeof o;
    } : function (o) {
      return o && "function" == typeof Symbol && o.constructor === Symbol && o !== Symbol.prototype ? "symbol" : typeof o;
    }, _typeof(o);
  }

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

  function tree_add$2(d) {
    const x = +this._x.call(null, d);
    return add$2(this.cover(x), x, d);
  }

  function add$2(tree, x, d) {
    if (isNaN(x)) return tree; // ignore invalid points

    var parent,
        node = tree._root,
        leaf = {data: d},
        x0 = tree._x0,
        x1 = tree._x1,
        xm,
        xp,
        right,
        i,
        j;

    // If the tree is empty, initialize the root as a leaf.
    if (!node) return tree._root = leaf, tree;

    // Find the existing leaf for the new point, or add it.
    while (node.length) {
      if (right = x >= (xm = (x0 + x1) / 2)) x0 = xm; else x1 = xm;
      if (parent = node, !(node = node[i = +right])) return parent[i] = leaf, tree;
    }

    // Is the new point is exactly coincident with the existing point?
    xp = +tree._x.call(null, node.data);
    if (x === xp) return leaf.next = node, parent ? parent[i] = leaf : tree._root = leaf, tree;

    // Otherwise, split the leaf node until the old and new point are separated.
    do {
      parent = parent ? parent[i] = new Array(2) : tree._root = new Array(2);
      if (right = x >= (xm = (x0 + x1) / 2)) x0 = xm; else x1 = xm;
    } while ((i = +right) === (j = +(xp >= xm)));
    return parent[j] = node, parent[i] = leaf, tree;
  }

  function addAll$2(data) {
    if (!Array.isArray(data)) data = Array.from(data);
    const n = data.length;
    const xz = new Float64Array(n);
    let x0 = Infinity,
        x1 = -Infinity;

    // Compute the points and their extent.
    for (let i = 0, x; i < n; ++i) {
      if (isNaN(x = +this._x.call(null, data[i]))) continue;
      xz[i] = x;
      if (x < x0) x0 = x;
      if (x > x1) x1 = x;
    }

    // If there were no (valid) points, abort.
    if (x0 > x1) return this;

    // Expand the tree to cover the new points.
    this.cover(x0).cover(x1);

    // Add the new points.
    for (let i = 0; i < n; ++i) {
      add$2(this, xz[i], data[i]);
    }

    return this;
  }

  function tree_cover$2(x) {
    if (isNaN(x = +x)) return this; // ignore invalid points

    var x0 = this._x0,
        x1 = this._x1;

    // If the binarytree has no extent, initialize them.
    // Integer extent are necessary so that if we later double the extent,
    // the existing half boundaries don’t change due to floating point error!
    if (isNaN(x0)) {
      x1 = (x0 = Math.floor(x)) + 1;
    }

    // Otherwise, double repeatedly to cover.
    else {
      var z = x1 - x0 || 1,
          node = this._root,
          parent,
          i;

      while (x0 > x || x >= x1) {
        i = +(x < x0);
        parent = new Array(2), parent[i] = node, node = parent, z *= 2;
        switch (i) {
          case 0: x1 = x0 + z; break;
          case 1: x0 = x1 - z; break;
        }
      }

      if (this._root && this._root.length) this._root = node;
    }

    this._x0 = x0;
    this._x1 = x1;
    return this;
  }

  function tree_data$2() {
    var data = [];
    this.visit(function(node) {
      if (!node.length) do data.push(node.data); while (node = node.next)
    });
    return data;
  }

  function tree_extent$2(_) {
    return arguments.length
        ? this.cover(+_[0][0]).cover(+_[1][0])
        : isNaN(this._x0) ? undefined : [[this._x0], [this._x1]];
  }

  function Half(node, x0, x1) {
    this.node = node;
    this.x0 = x0;
    this.x1 = x1;
  }

  function tree_find$2(x, radius) {
    var data,
        x0 = this._x0,
        x1,
        x2,
        x3 = this._x1,
        halves = [],
        node = this._root,
        q,
        i;

    if (node) halves.push(new Half(node, x0, x3));
    if (radius == null) radius = Infinity;
    else {
      x0 = x - radius;
      x3 = x + radius;
    }

    while (q = halves.pop()) {

      // Stop searching if this half can’t contain a closer node.
      if (!(node = q.node)
          || (x1 = q.x0) > x3
          || (x2 = q.x1) < x0) continue;

      // Bisect the current half.
      if (node.length) {
        var xm = (x1 + x2) / 2;

        halves.push(
          new Half(node[1], xm, x2),
          new Half(node[0], x1, xm)
        );

        // Visit the closest half first.
        if (i = +(x >= xm)) {
          q = halves[halves.length - 1];
          halves[halves.length - 1] = halves[halves.length - 1 - i];
          halves[halves.length - 1 - i] = q;
        }
      }

      // Visit this point. (Visiting coincident points isn’t necessary!)
      else {
        var d = Math.abs(x - +this._x.call(null, node.data));
        if (d < radius) {
          radius = d;
          x0 = x - d;
          x3 = x + d;
          data = node.data;
        }
      }
    }

    return data;
  }

  function tree_remove$2(d) {
    if (isNaN(x = +this._x.call(null, d))) return this; // ignore invalid points

    var parent,
        node = this._root,
        retainer,
        previous,
        next,
        x0 = this._x0,
        x1 = this._x1,
        x,
        xm,
        right,
        i,
        j;

    // If the tree is empty, initialize the root as a leaf.
    if (!node) return this;

    // Find the leaf node for the point.
    // While descending, also retain the deepest parent with a non-removed sibling.
    if (node.length) while (true) {
      if (right = x >= (xm = (x0 + x1) / 2)) x0 = xm; else x1 = xm;
      if (!(parent = node, node = node[i = +right])) return this;
      if (!node.length) break;
      if (parent[(i + 1) & 1]) retainer = parent, j = i;
    }

    // Find the point to remove.
    while (node.data !== d) if (!(previous = node, node = node.next)) return this;
    if (next = node.next) delete node.next;

    // If there are multiple coincident points, remove just the point.
    if (previous) return (next ? previous.next = next : delete previous.next), this;

    // If this is the root point, remove it.
    if (!parent) return this._root = next, this;

    // Remove this leaf.
    next ? parent[i] = next : delete parent[i];

    // If the parent now contains exactly one leaf, collapse superfluous parents.
    if ((node = parent[0] || parent[1])
        && node === (parent[1] || parent[0])
        && !node.length) {
      if (retainer) retainer[j] = node;
      else this._root = node;
    }

    return this;
  }

  function removeAll$2(data) {
    for (var i = 0, n = data.length; i < n; ++i) this.remove(data[i]);
    return this;
  }

  function tree_root$2() {
    return this._root;
  }

  function tree_size$2() {
    var size = 0;
    this.visit(function(node) {
      if (!node.length) do ++size; while (node = node.next)
    });
    return size;
  }

  function tree_visit$2(callback) {
    var halves = [], q, node = this._root, child, x0, x1;
    if (node) halves.push(new Half(node, this._x0, this._x1));
    while (q = halves.pop()) {
      if (!callback(node = q.node, x0 = q.x0, x1 = q.x1) && node.length) {
        var xm = (x0 + x1) / 2;
        if (child = node[1]) halves.push(new Half(child, xm, x1));
        if (child = node[0]) halves.push(new Half(child, x0, xm));
      }
    }
    return this;
  }

  function tree_visitAfter$2(callback) {
    var halves = [], next = [], q;
    if (this._root) halves.push(new Half(this._root, this._x0, this._x1));
    while (q = halves.pop()) {
      var node = q.node;
      if (node.length) {
        var child, x0 = q.x0, x1 = q.x1, xm = (x0 + x1) / 2;
        if (child = node[0]) halves.push(new Half(child, x0, xm));
        if (child = node[1]) halves.push(new Half(child, xm, x1));
      }
      next.push(q);
    }
    while (q = next.pop()) {
      callback(q.node, q.x0, q.x1);
    }
    return this;
  }

  function defaultX$2(d) {
    return d[0];
  }

  function tree_x$2(_) {
    return arguments.length ? (this._x = _, this) : this._x;
  }

  function binarytree(nodes, x) {
    var tree = new Binarytree(x == null ? defaultX$2 : x, NaN, NaN);
    return nodes == null ? tree : tree.addAll(nodes);
  }

  function Binarytree(x, x0, x1) {
    this._x = x;
    this._x0 = x0;
    this._x1 = x1;
    this._root = undefined;
  }

  function leaf_copy$2(leaf) {
    var copy = {data: leaf.data}, next = copy;
    while (leaf = leaf.next) next = next.next = {data: leaf.data};
    return copy;
  }

  var treeProto$2 = binarytree.prototype = Binarytree.prototype;

  treeProto$2.copy = function() {
    var copy = new Binarytree(this._x, this._x0, this._x1),
        node = this._root,
        nodes,
        child;

    if (!node) return copy;

    if (!node.length) return copy._root = leaf_copy$2(node), copy;

    nodes = [{source: node, target: copy._root = new Array(2)}];
    while (node = nodes.pop()) {
      for (var i = 0; i < 2; ++i) {
        if (child = node.source[i]) {
          if (child.length) nodes.push({source: child, target: node.target[i] = new Array(2)});
          else node.target[i] = leaf_copy$2(child);
        }
      }
    }

    return copy;
  };

  treeProto$2.add = tree_add$2;
  treeProto$2.addAll = addAll$2;
  treeProto$2.cover = tree_cover$2;
  treeProto$2.data = tree_data$2;
  treeProto$2.extent = tree_extent$2;
  treeProto$2.find = tree_find$2;
  treeProto$2.remove = tree_remove$2;
  treeProto$2.removeAll = removeAll$2;
  treeProto$2.root = tree_root$2;
  treeProto$2.size = tree_size$2;
  treeProto$2.visit = tree_visit$2;
  treeProto$2.visitAfter = tree_visitAfter$2;
  treeProto$2.x = tree_x$2;

  function tree_add$1(d) {
    const x = +this._x.call(null, d),
        y = +this._y.call(null, d);
    return add$1(this.cover(x, y), x, y, d);
  }

  function add$1(tree, x, y, d) {
    if (isNaN(x) || isNaN(y)) return tree; // ignore invalid points

    var parent,
        node = tree._root,
        leaf = {data: d},
        x0 = tree._x0,
        y0 = tree._y0,
        x1 = tree._x1,
        y1 = tree._y1,
        xm,
        ym,
        xp,
        yp,
        right,
        bottom,
        i,
        j;

    // If the tree is empty, initialize the root as a leaf.
    if (!node) return tree._root = leaf, tree;

    // Find the existing leaf for the new point, or add it.
    while (node.length) {
      if (right = x >= (xm = (x0 + x1) / 2)) x0 = xm; else x1 = xm;
      if (bottom = y >= (ym = (y0 + y1) / 2)) y0 = ym; else y1 = ym;
      if (parent = node, !(node = node[i = bottom << 1 | right])) return parent[i] = leaf, tree;
    }

    // Is the new point is exactly coincident with the existing point?
    xp = +tree._x.call(null, node.data);
    yp = +tree._y.call(null, node.data);
    if (x === xp && y === yp) return leaf.next = node, parent ? parent[i] = leaf : tree._root = leaf, tree;

    // Otherwise, split the leaf node until the old and new point are separated.
    do {
      parent = parent ? parent[i] = new Array(4) : tree._root = new Array(4);
      if (right = x >= (xm = (x0 + x1) / 2)) x0 = xm; else x1 = xm;
      if (bottom = y >= (ym = (y0 + y1) / 2)) y0 = ym; else y1 = ym;
    } while ((i = bottom << 1 | right) === (j = (yp >= ym) << 1 | (xp >= xm)));
    return parent[j] = node, parent[i] = leaf, tree;
  }

  function addAll$1(data) {
    var d, i, n = data.length,
        x,
        y,
        xz = new Array(n),
        yz = new Array(n),
        x0 = Infinity,
        y0 = Infinity,
        x1 = -Infinity,
        y1 = -Infinity;

    // Compute the points and their extent.
    for (i = 0; i < n; ++i) {
      if (isNaN(x = +this._x.call(null, d = data[i])) || isNaN(y = +this._y.call(null, d))) continue;
      xz[i] = x;
      yz[i] = y;
      if (x < x0) x0 = x;
      if (x > x1) x1 = x;
      if (y < y0) y0 = y;
      if (y > y1) y1 = y;
    }

    // If there were no (valid) points, abort.
    if (x0 > x1 || y0 > y1) return this;

    // Expand the tree to cover the new points.
    this.cover(x0, y0).cover(x1, y1);

    // Add the new points.
    for (i = 0; i < n; ++i) {
      add$1(this, xz[i], yz[i], data[i]);
    }

    return this;
  }

  function tree_cover$1(x, y) {
    if (isNaN(x = +x) || isNaN(y = +y)) return this; // ignore invalid points

    var x0 = this._x0,
        y0 = this._y0,
        x1 = this._x1,
        y1 = this._y1;

    // If the quadtree has no extent, initialize them.
    // Integer extent are necessary so that if we later double the extent,
    // the existing quadrant boundaries don’t change due to floating point error!
    if (isNaN(x0)) {
      x1 = (x0 = Math.floor(x)) + 1;
      y1 = (y0 = Math.floor(y)) + 1;
    }

    // Otherwise, double repeatedly to cover.
    else {
      var z = x1 - x0 || 1,
          node = this._root,
          parent,
          i;

      while (x0 > x || x >= x1 || y0 > y || y >= y1) {
        i = (y < y0) << 1 | (x < x0);
        parent = new Array(4), parent[i] = node, node = parent, z *= 2;
        switch (i) {
          case 0: x1 = x0 + z, y1 = y0 + z; break;
          case 1: x0 = x1 - z, y1 = y0 + z; break;
          case 2: x1 = x0 + z, y0 = y1 - z; break;
          case 3: x0 = x1 - z, y0 = y1 - z; break;
        }
      }

      if (this._root && this._root.length) this._root = node;
    }

    this._x0 = x0;
    this._y0 = y0;
    this._x1 = x1;
    this._y1 = y1;
    return this;
  }

  function tree_data$1() {
    var data = [];
    this.visit(function(node) {
      if (!node.length) do data.push(node.data); while (node = node.next)
    });
    return data;
  }

  function tree_extent$1(_) {
    return arguments.length
        ? this.cover(+_[0][0], +_[0][1]).cover(+_[1][0], +_[1][1])
        : isNaN(this._x0) ? undefined : [[this._x0, this._y0], [this._x1, this._y1]];
  }

  function Quad(node, x0, y0, x1, y1) {
    this.node = node;
    this.x0 = x0;
    this.y0 = y0;
    this.x1 = x1;
    this.y1 = y1;
  }

  function tree_find$1(x, y, radius) {
    var data,
        x0 = this._x0,
        y0 = this._y0,
        x1,
        y1,
        x2,
        y2,
        x3 = this._x1,
        y3 = this._y1,
        quads = [],
        node = this._root,
        q,
        i;

    if (node) quads.push(new Quad(node, x0, y0, x3, y3));
    if (radius == null) radius = Infinity;
    else {
      x0 = x - radius, y0 = y - radius;
      x3 = x + radius, y3 = y + radius;
      radius *= radius;
    }

    while (q = quads.pop()) {

      // Stop searching if this quadrant can’t contain a closer node.
      if (!(node = q.node)
          || (x1 = q.x0) > x3
          || (y1 = q.y0) > y3
          || (x2 = q.x1) < x0
          || (y2 = q.y1) < y0) continue;

      // Bisect the current quadrant.
      if (node.length) {
        var xm = (x1 + x2) / 2,
            ym = (y1 + y2) / 2;

        quads.push(
          new Quad(node[3], xm, ym, x2, y2),
          new Quad(node[2], x1, ym, xm, y2),
          new Quad(node[1], xm, y1, x2, ym),
          new Quad(node[0], x1, y1, xm, ym)
        );

        // Visit the closest quadrant first.
        if (i = (y >= ym) << 1 | (x >= xm)) {
          q = quads[quads.length - 1];
          quads[quads.length - 1] = quads[quads.length - 1 - i];
          quads[quads.length - 1 - i] = q;
        }
      }

      // Visit this point. (Visiting coincident points isn’t necessary!)
      else {
        var dx = x - +this._x.call(null, node.data),
            dy = y - +this._y.call(null, node.data),
            d2 = dx * dx + dy * dy;
        if (d2 < radius) {
          var d = Math.sqrt(radius = d2);
          x0 = x - d, y0 = y - d;
          x3 = x + d, y3 = y + d;
          data = node.data;
        }
      }
    }

    return data;
  }

  function tree_remove$1(d) {
    if (isNaN(x = +this._x.call(null, d)) || isNaN(y = +this._y.call(null, d))) return this; // ignore invalid points

    var parent,
        node = this._root,
        retainer,
        previous,
        next,
        x0 = this._x0,
        y0 = this._y0,
        x1 = this._x1,
        y1 = this._y1,
        x,
        y,
        xm,
        ym,
        right,
        bottom,
        i,
        j;

    // If the tree is empty, initialize the root as a leaf.
    if (!node) return this;

    // Find the leaf node for the point.
    // While descending, also retain the deepest parent with a non-removed sibling.
    if (node.length) while (true) {
      if (right = x >= (xm = (x0 + x1) / 2)) x0 = xm; else x1 = xm;
      if (bottom = y >= (ym = (y0 + y1) / 2)) y0 = ym; else y1 = ym;
      if (!(parent = node, node = node[i = bottom << 1 | right])) return this;
      if (!node.length) break;
      if (parent[(i + 1) & 3] || parent[(i + 2) & 3] || parent[(i + 3) & 3]) retainer = parent, j = i;
    }

    // Find the point to remove.
    while (node.data !== d) if (!(previous = node, node = node.next)) return this;
    if (next = node.next) delete node.next;

    // If there are multiple coincident points, remove just the point.
    if (previous) return (next ? previous.next = next : delete previous.next), this;

    // If this is the root point, remove it.
    if (!parent) return this._root = next, this;

    // Remove this leaf.
    next ? parent[i] = next : delete parent[i];

    // If the parent now contains exactly one leaf, collapse superfluous parents.
    if ((node = parent[0] || parent[1] || parent[2] || parent[3])
        && node === (parent[3] || parent[2] || parent[1] || parent[0])
        && !node.length) {
      if (retainer) retainer[j] = node;
      else this._root = node;
    }

    return this;
  }

  function removeAll$1(data) {
    for (var i = 0, n = data.length; i < n; ++i) this.remove(data[i]);
    return this;
  }

  function tree_root$1() {
    return this._root;
  }

  function tree_size$1() {
    var size = 0;
    this.visit(function(node) {
      if (!node.length) do ++size; while (node = node.next)
    });
    return size;
  }

  function tree_visit$1(callback) {
    var quads = [], q, node = this._root, child, x0, y0, x1, y1;
    if (node) quads.push(new Quad(node, this._x0, this._y0, this._x1, this._y1));
    while (q = quads.pop()) {
      if (!callback(node = q.node, x0 = q.x0, y0 = q.y0, x1 = q.x1, y1 = q.y1) && node.length) {
        var xm = (x0 + x1) / 2, ym = (y0 + y1) / 2;
        if (child = node[3]) quads.push(new Quad(child, xm, ym, x1, y1));
        if (child = node[2]) quads.push(new Quad(child, x0, ym, xm, y1));
        if (child = node[1]) quads.push(new Quad(child, xm, y0, x1, ym));
        if (child = node[0]) quads.push(new Quad(child, x0, y0, xm, ym));
      }
    }
    return this;
  }

  function tree_visitAfter$1(callback) {
    var quads = [], next = [], q;
    if (this._root) quads.push(new Quad(this._root, this._x0, this._y0, this._x1, this._y1));
    while (q = quads.pop()) {
      var node = q.node;
      if (node.length) {
        var child, x0 = q.x0, y0 = q.y0, x1 = q.x1, y1 = q.y1, xm = (x0 + x1) / 2, ym = (y0 + y1) / 2;
        if (child = node[0]) quads.push(new Quad(child, x0, y0, xm, ym));
        if (child = node[1]) quads.push(new Quad(child, xm, y0, x1, ym));
        if (child = node[2]) quads.push(new Quad(child, x0, ym, xm, y1));
        if (child = node[3]) quads.push(new Quad(child, xm, ym, x1, y1));
      }
      next.push(q);
    }
    while (q = next.pop()) {
      callback(q.node, q.x0, q.y0, q.x1, q.y1);
    }
    return this;
  }

  function defaultX$1(d) {
    return d[0];
  }

  function tree_x$1(_) {
    return arguments.length ? (this._x = _, this) : this._x;
  }

  function defaultY$1(d) {
    return d[1];
  }

  function tree_y$1(_) {
    return arguments.length ? (this._y = _, this) : this._y;
  }

  function quadtree(nodes, x, y) {
    var tree = new Quadtree(x == null ? defaultX$1 : x, y == null ? defaultY$1 : y, NaN, NaN, NaN, NaN);
    return nodes == null ? tree : tree.addAll(nodes);
  }

  function Quadtree(x, y, x0, y0, x1, y1) {
    this._x = x;
    this._y = y;
    this._x0 = x0;
    this._y0 = y0;
    this._x1 = x1;
    this._y1 = y1;
    this._root = undefined;
  }

  function leaf_copy$1(leaf) {
    var copy = {data: leaf.data}, next = copy;
    while (leaf = leaf.next) next = next.next = {data: leaf.data};
    return copy;
  }

  var treeProto$1 = quadtree.prototype = Quadtree.prototype;

  treeProto$1.copy = function() {
    var copy = new Quadtree(this._x, this._y, this._x0, this._y0, this._x1, this._y1),
        node = this._root,
        nodes,
        child;

    if (!node) return copy;

    if (!node.length) return copy._root = leaf_copy$1(node), copy;

    nodes = [{source: node, target: copy._root = new Array(4)}];
    while (node = nodes.pop()) {
      for (var i = 0; i < 4; ++i) {
        if (child = node.source[i]) {
          if (child.length) nodes.push({source: child, target: node.target[i] = new Array(4)});
          else node.target[i] = leaf_copy$1(child);
        }
      }
    }

    return copy;
  };

  treeProto$1.add = tree_add$1;
  treeProto$1.addAll = addAll$1;
  treeProto$1.cover = tree_cover$1;
  treeProto$1.data = tree_data$1;
  treeProto$1.extent = tree_extent$1;
  treeProto$1.find = tree_find$1;
  treeProto$1.remove = tree_remove$1;
  treeProto$1.removeAll = removeAll$1;
  treeProto$1.root = tree_root$1;
  treeProto$1.size = tree_size$1;
  treeProto$1.visit = tree_visit$1;
  treeProto$1.visitAfter = tree_visitAfter$1;
  treeProto$1.x = tree_x$1;
  treeProto$1.y = tree_y$1;

  function tree_add(d) {
    const x = +this._x.call(null, d),
        y = +this._y.call(null, d),
        z = +this._z.call(null, d);
    return add(this.cover(x, y, z), x, y, z, d);
  }

  function add(tree, x, y, z, d) {
    if (isNaN(x) || isNaN(y) || isNaN(z)) return tree; // ignore invalid points

    var parent,
        node = tree._root,
        leaf = {data: d},
        x0 = tree._x0,
        y0 = tree._y0,
        z0 = tree._z0,
        x1 = tree._x1,
        y1 = tree._y1,
        z1 = tree._z1,
        xm,
        ym,
        zm,
        xp,
        yp,
        zp,
        right,
        bottom,
        deep,
        i,
        j;

    // If the tree is empty, initialize the root as a leaf.
    if (!node) return tree._root = leaf, tree;

    // Find the existing leaf for the new point, or add it.
    while (node.length) {
      if (right = x >= (xm = (x0 + x1) / 2)) x0 = xm; else x1 = xm;
      if (bottom = y >= (ym = (y0 + y1) / 2)) y0 = ym; else y1 = ym;
      if (deep = z >= (zm = (z0 + z1) / 2)) z0 = zm; else z1 = zm;
      if (parent = node, !(node = node[i = deep << 2 | bottom << 1 | right])) return parent[i] = leaf, tree;
    }

    // Is the new point is exactly coincident with the existing point?
    xp = +tree._x.call(null, node.data);
    yp = +tree._y.call(null, node.data);
    zp = +tree._z.call(null, node.data);
    if (x === xp && y === yp && z === zp) return leaf.next = node, parent ? parent[i] = leaf : tree._root = leaf, tree;

    // Otherwise, split the leaf node until the old and new point are separated.
    do {
      parent = parent ? parent[i] = new Array(8) : tree._root = new Array(8);
      if (right = x >= (xm = (x0 + x1) / 2)) x0 = xm; else x1 = xm;
      if (bottom = y >= (ym = (y0 + y1) / 2)) y0 = ym; else y1 = ym;
      if (deep = z >= (zm = (z0 + z1) / 2)) z0 = zm; else z1 = zm;
    } while ((i = deep << 2 | bottom << 1 | right) === (j = (zp >= zm) << 2 | (yp >= ym) << 1 | (xp >= xm)));
    return parent[j] = node, parent[i] = leaf, tree;
  }

  function addAll(data) {
    if (!Array.isArray(data)) data = Array.from(data);
    const n = data.length;
    const xz = new Float64Array(n);
    const yz = new Float64Array(n);
    const zz = new Float64Array(n);
    let x0 = Infinity,
        y0 = Infinity,
        z0 = Infinity,
        x1 = -Infinity,
        y1 = -Infinity,
        z1 = -Infinity;

    // Compute the points and their extent.
    for (let i = 0, d, x, y, z; i < n; ++i) {
      if (isNaN(x = +this._x.call(null, d = data[i])) || isNaN(y = +this._y.call(null, d)) || isNaN(z = +this._z.call(null, d))) continue;
      xz[i] = x;
      yz[i] = y;
      zz[i] = z;
      if (x < x0) x0 = x;
      if (x > x1) x1 = x;
      if (y < y0) y0 = y;
      if (y > y1) y1 = y;
      if (z < z0) z0 = z;
      if (z > z1) z1 = z;
    }

    // If there were no (valid) points, abort.
    if (x0 > x1 || y0 > y1 || z0 > z1) return this;

    // Expand the tree to cover the new points.
    this.cover(x0, y0, z0).cover(x1, y1, z1);

    // Add the new points.
    for (let i = 0; i < n; ++i) {
      add(this, xz[i], yz[i], zz[i], data[i]);
    }

    return this;
  }

  function tree_cover(x, y, z) {
    if (isNaN(x = +x) || isNaN(y = +y) || isNaN(z = +z)) return this; // ignore invalid points

    var x0 = this._x0,
        y0 = this._y0,
        z0 = this._z0,
        x1 = this._x1,
        y1 = this._y1,
        z1 = this._z1;

    // If the octree has no extent, initialize them.
    // Integer extent are necessary so that if we later double the extent,
    // the existing octant boundaries don’t change due to floating point error!
    if (isNaN(x0)) {
      x1 = (x0 = Math.floor(x)) + 1;
      y1 = (y0 = Math.floor(y)) + 1;
      z1 = (z0 = Math.floor(z)) + 1;
    }

    // Otherwise, double repeatedly to cover.
    else {
      var t = x1 - x0 || 1,
          node = this._root,
          parent,
          i;

      while (x0 > x || x >= x1 || y0 > y || y >= y1 || z0 > z || z >= z1) {
        i = (z < z0) << 2 | (y < y0) << 1 | (x < x0);
        parent = new Array(8), parent[i] = node, node = parent, t *= 2;
        switch (i) {
          case 0: x1 = x0 + t, y1 = y0 + t, z1 = z0 + t; break;
          case 1: x0 = x1 - t, y1 = y0 + t, z1 = z0 + t; break;
          case 2: x1 = x0 + t, y0 = y1 - t, z1 = z0 + t; break;
          case 3: x0 = x1 - t, y0 = y1 - t, z1 = z0 + t; break;
          case 4: x1 = x0 + t, y1 = y0 + t, z0 = z1 - t; break;
          case 5: x0 = x1 - t, y1 = y0 + t, z0 = z1 - t; break;
          case 6: x1 = x0 + t, y0 = y1 - t, z0 = z1 - t; break;
          case 7: x0 = x1 - t, y0 = y1 - t, z0 = z1 - t; break;
        }
      }

      if (this._root && this._root.length) this._root = node;
    }

    this._x0 = x0;
    this._y0 = y0;
    this._z0 = z0;
    this._x1 = x1;
    this._y1 = y1;
    this._z1 = z1;
    return this;
  }

  function tree_data() {
    var data = [];
    this.visit(function(node) {
      if (!node.length) do data.push(node.data); while (node = node.next)
    });
    return data;
  }

  function tree_extent(_) {
    return arguments.length
        ? this.cover(+_[0][0], +_[0][1], +_[0][2]).cover(+_[1][0], +_[1][1], +_[1][2])
        : isNaN(this._x0) ? undefined : [[this._x0, this._y0, this._z0], [this._x1, this._y1, this._z1]];
  }

  function Octant(node, x0, y0, z0, x1, y1, z1) {
    this.node = node;
    this.x0 = x0;
    this.y0 = y0;
    this.z0 = z0;
    this.x1 = x1;
    this.y1 = y1;
    this.z1 = z1;
  }

  function tree_find(x, y, z, radius) {
    var data,
        x0 = this._x0,
        y0 = this._y0,
        z0 = this._z0,
        x1,
        y1,
        z1,
        x2,
        y2,
        z2,
        x3 = this._x1,
        y3 = this._y1,
        z3 = this._z1,
        octs = [],
        node = this._root,
        q,
        i;

    if (node) octs.push(new Octant(node, x0, y0, z0, x3, y3, z3));
    if (radius == null) radius = Infinity;
    else {
      x0 = x - radius, y0 = y - radius, z0 = z - radius;
      x3 = x + radius, y3 = y + radius, z3 = z + radius;
      radius *= radius;
    }

    while (q = octs.pop()) {

      // Stop searching if this octant can’t contain a closer node.
      if (!(node = q.node)
          || (x1 = q.x0) > x3
          || (y1 = q.y0) > y3
          || (z1 = q.z0) > z3
          || (x2 = q.x1) < x0
          || (y2 = q.y1) < y0
          || (z2 = q.z1) < z0) continue;

      // Bisect the current octant.
      if (node.length) {
        var xm = (x1 + x2) / 2,
            ym = (y1 + y2) / 2,
            zm = (z1 + z2) / 2;

        octs.push(
          new Octant(node[7], xm, ym, zm, x2, y2, z2),
          new Octant(node[6], x1, ym, zm, xm, y2, z2),
          new Octant(node[5], xm, y1, zm, x2, ym, z2),
          new Octant(node[4], x1, y1, zm, xm, ym, z2),
          new Octant(node[3], xm, ym, z1, x2, y2, zm),
          new Octant(node[2], x1, ym, z1, xm, y2, zm),
          new Octant(node[1], xm, y1, z1, x2, ym, zm),
          new Octant(node[0], x1, y1, z1, xm, ym, zm)
        );

        // Visit the closest octant first.
        if (i = (z >= zm) << 2 | (y >= ym) << 1 | (x >= xm)) {
          q = octs[octs.length - 1];
          octs[octs.length - 1] = octs[octs.length - 1 - i];
          octs[octs.length - 1 - i] = q;
        }
      }

      // Visit this point. (Visiting coincident points isn’t necessary!)
      else {
        var dx = x - +this._x.call(null, node.data),
            dy = y - +this._y.call(null, node.data),
            dz = z - +this._z.call(null, node.data),
            d2 = dx * dx + dy * dy + dz * dz;
        if (d2 < radius) {
          var d = Math.sqrt(radius = d2);
          x0 = x - d, y0 = y - d, z0 = z - d;
          x3 = x + d, y3 = y + d, z3 = z + d;
          data = node.data;
        }
      }
    }

    return data;
  }

  const distance = (x1, y1, z1, x2, y2, z2) => Math.sqrt((x1-x2)**2 + (y1-y2)**2 + (z1-z2)**2);

  function findAllWithinRadius(x, y, z, radius) {
    const result = [];

    const xMin = x - radius;
    const yMin = y - radius;
    const zMin = z - radius;
    const xMax = x + radius;
    const yMax = y + radius;
    const zMax = z + radius;

    this.visit((node, x1, y1, z1, x2, y2, z2) => {
      if (!node.length) {
        do {
          const d = node.data;
          if (distance(x, y, z, this._x(d), this._y(d), this._z(d)) <= radius) {
            result.push(d);
          }
        } while (node = node.next);
      }
      return x1 > xMax || y1 > yMax || z1 > zMax || x2 < xMin || y2 < yMin || z2 < zMin;
    });

    return result;
  }

  function tree_remove(d) {
    if (isNaN(x = +this._x.call(null, d)) || isNaN(y = +this._y.call(null, d)) || isNaN(z = +this._z.call(null, d))) return this; // ignore invalid points

    var parent,
        node = this._root,
        retainer,
        previous,
        next,
        x0 = this._x0,
        y0 = this._y0,
        z0 = this._z0,
        x1 = this._x1,
        y1 = this._y1,
        z1 = this._z1,
        x,
        y,
        z,
        xm,
        ym,
        zm,
        right,
        bottom,
        deep,
        i,
        j;

    // If the tree is empty, initialize the root as a leaf.
    if (!node) return this;

    // Find the leaf node for the point.
    // While descending, also retain the deepest parent with a non-removed sibling.
    if (node.length) while (true) {
      if (right = x >= (xm = (x0 + x1) / 2)) x0 = xm; else x1 = xm;
      if (bottom = y >= (ym = (y0 + y1) / 2)) y0 = ym; else y1 = ym;
      if (deep = z >= (zm = (z0 + z1) / 2)) z0 = zm; else z1 = zm;
      if (!(parent = node, node = node[i = deep << 2 | bottom << 1 | right])) return this;
      if (!node.length) break;
      if (parent[(i + 1) & 7] || parent[(i + 2) & 7] || parent[(i + 3) & 7] || parent[(i + 4) & 7] || parent[(i + 5) & 7] || parent[(i + 6) & 7] || parent[(i + 7) & 7]) retainer = parent, j = i;
    }

    // Find the point to remove.
    while (node.data !== d) if (!(previous = node, node = node.next)) return this;
    if (next = node.next) delete node.next;

    // If there are multiple coincident points, remove just the point.
    if (previous) return (next ? previous.next = next : delete previous.next), this;

    // If this is the root point, remove it.
    if (!parent) return this._root = next, this;

    // Remove this leaf.
    next ? parent[i] = next : delete parent[i];

    // If the parent now contains exactly one leaf, collapse superfluous parents.
    if ((node = parent[0] || parent[1] || parent[2] || parent[3] || parent[4] || parent[5] || parent[6] || parent[7])
        && node === (parent[7] || parent[6] || parent[5] || parent[4] || parent[3] || parent[2] || parent[1] || parent[0])
        && !node.length) {
      if (retainer) retainer[j] = node;
      else this._root = node;
    }

    return this;
  }

  function removeAll(data) {
    for (var i = 0, n = data.length; i < n; ++i) this.remove(data[i]);
    return this;
  }

  function tree_root() {
    return this._root;
  }

  function tree_size() {
    var size = 0;
    this.visit(function(node) {
      if (!node.length) do ++size; while (node = node.next)
    });
    return size;
  }

  function tree_visit(callback) {
    var octs = [], q, node = this._root, child, x0, y0, z0, x1, y1, z1;
    if (node) octs.push(new Octant(node, this._x0, this._y0, this._z0, this._x1, this._y1, this._z1));
    while (q = octs.pop()) {
      if (!callback(node = q.node, x0 = q.x0, y0 = q.y0, z0 = q.z0, x1 = q.x1, y1 = q.y1, z1 = q.z1) && node.length) {
        var xm = (x0 + x1) / 2, ym = (y0 + y1) / 2, zm = (z0 + z1) / 2;
        if (child = node[7]) octs.push(new Octant(child, xm, ym, zm, x1, y1, z1));
        if (child = node[6]) octs.push(new Octant(child, x0, ym, zm, xm, y1, z1));
        if (child = node[5]) octs.push(new Octant(child, xm, y0, zm, x1, ym, z1));
        if (child = node[4]) octs.push(new Octant(child, x0, y0, zm, xm, ym, z1));
        if (child = node[3]) octs.push(new Octant(child, xm, ym, z0, x1, y1, zm));
        if (child = node[2]) octs.push(new Octant(child, x0, ym, z0, xm, y1, zm));
        if (child = node[1]) octs.push(new Octant(child, xm, y0, z0, x1, ym, zm));
        if (child = node[0]) octs.push(new Octant(child, x0, y0, z0, xm, ym, zm));
      }
    }
    return this;
  }

  function tree_visitAfter(callback) {
    var octs = [], next = [], q;
    if (this._root) octs.push(new Octant(this._root, this._x0, this._y0, this._z0, this._x1, this._y1, this._z1));
    while (q = octs.pop()) {
      var node = q.node;
      if (node.length) {
        var child, x0 = q.x0, y0 = q.y0, z0 = q.z0, x1 = q.x1, y1 = q.y1, z1 = q.z1, xm = (x0 + x1) / 2, ym = (y0 + y1) / 2, zm = (z0 + z1) / 2;
        if (child = node[0]) octs.push(new Octant(child, x0, y0, z0, xm, ym, zm));
        if (child = node[1]) octs.push(new Octant(child, xm, y0, z0, x1, ym, zm));
        if (child = node[2]) octs.push(new Octant(child, x0, ym, z0, xm, y1, zm));
        if (child = node[3]) octs.push(new Octant(child, xm, ym, z0, x1, y1, zm));
        if (child = node[4]) octs.push(new Octant(child, x0, y0, zm, xm, ym, z1));
        if (child = node[5]) octs.push(new Octant(child, xm, y0, zm, x1, ym, z1));
        if (child = node[6]) octs.push(new Octant(child, x0, ym, zm, xm, y1, z1));
        if (child = node[7]) octs.push(new Octant(child, xm, ym, zm, x1, y1, z1));
      }
      next.push(q);
    }
    while (q = next.pop()) {
      callback(q.node, q.x0, q.y0, q.z0, q.x1, q.y1, q.z1);
    }
    return this;
  }

  function defaultX(d) {
    return d[0];
  }

  function tree_x(_) {
    return arguments.length ? (this._x = _, this) : this._x;
  }

  function defaultY(d) {
    return d[1];
  }

  function tree_y(_) {
    return arguments.length ? (this._y = _, this) : this._y;
  }

  function defaultZ(d) {
    return d[2];
  }

  function tree_z(_) {
    return arguments.length ? (this._z = _, this) : this._z;
  }

  function octree(nodes, x, y, z) {
    var tree = new Octree(x == null ? defaultX : x, y == null ? defaultY : y, z == null ? defaultZ : z, NaN, NaN, NaN, NaN, NaN, NaN);
    return nodes == null ? tree : tree.addAll(nodes);
  }

  function Octree(x, y, z, x0, y0, z0, x1, y1, z1) {
    this._x = x;
    this._y = y;
    this._z = z;
    this._x0 = x0;
    this._y0 = y0;
    this._z0 = z0;
    this._x1 = x1;
    this._y1 = y1;
    this._z1 = z1;
    this._root = undefined;
  }

  function leaf_copy(leaf) {
    var copy = {data: leaf.data}, next = copy;
    while (leaf = leaf.next) next = next.next = {data: leaf.data};
    return copy;
  }

  var treeProto = octree.prototype = Octree.prototype;

  treeProto.copy = function() {
    var copy = new Octree(this._x, this._y, this._z, this._x0, this._y0, this._z0, this._x1, this._y1, this._z1),
        node = this._root,
        nodes,
        child;

    if (!node) return copy;

    if (!node.length) return copy._root = leaf_copy(node), copy;

    nodes = [{source: node, target: copy._root = new Array(8)}];
    while (node = nodes.pop()) {
      for (var i = 0; i < 8; ++i) {
        if (child = node.source[i]) {
          if (child.length) nodes.push({source: child, target: node.target[i] = new Array(8)});
          else node.target[i] = leaf_copy(child);
        }
      }
    }

    return copy;
  };

  treeProto.add = tree_add;
  treeProto.addAll = addAll;
  treeProto.cover = tree_cover;
  treeProto.data = tree_data;
  treeProto.extent = tree_extent;
  treeProto.find = tree_find;
  treeProto.findAllWithinRadius = findAllWithinRadius;
  treeProto.remove = tree_remove;
  treeProto.removeAll = removeAll;
  treeProto.root = tree_root;
  treeProto.size = tree_size;
  treeProto.visit = tree_visit;
  treeProto.visitAfter = tree_visitAfter;
  treeProto.x = tree_x;
  treeProto.y = tree_y;
  treeProto.z = tree_z;

  function magnetic () {
    var nDim,
      nodes = [],
      links = [],
      id = function id(node) {
        return node.index;
      },
      // accessor: node unique id
      charge = function charge(node) {
        return 100;
      },
      // accessor: number (equivalent to node mass)
      strength = function strength(link) {
        return 1;
      },
      // accessor: number (equivalent to G constant)
      polarity = function polarity(q1, q2) {
        return null;
      },
      // boolean or null (asymmetrical)
      distanceWeight = function distanceWeight(d) {
        return 1 / (d * d);
      },
      // Intensity falls with the square of the distance (inverse-square law)
      theta = 0.9;
    function force(alpha) {
      if (links.length) {
        // Pre-set node pairs
        for (var i = 0; i < links.length; i++) {
          var link = links[i],
            dx = link.target.x - link.source.x,
            dy = link.target.y - link.source.y || 0,
            dz = link.target.z - link.source.z || 0,
            d = distance(dx, dy, dz);
          if (d === 0) continue;
          var relStrength = alpha * strength(link) * distanceWeight(d);
          var qSrc = charge(link.source),
            qTgt = charge(link.target);

          // Set attract/repel polarity
          var linkPolarity = polarity(qSrc, qTgt);
          var sourceAcceleration = signedCharge(qTgt, linkPolarity) * relStrength;
          var targetAcceleration = signedCharge(qSrc, linkPolarity) * relStrength;
          link.source.vx += dx / d * sourceAcceleration;
          link.target.vx -= dx / d * targetAcceleration;
          if (nDim > 1) {
            link.source.vy += dy / d * sourceAcceleration;
            link.target.vy -= dy / d * targetAcceleration;
          }
          if (nDim > 2) {
            link.source.vz += dz / d * sourceAcceleration;
            link.target.vz -= dz / d * targetAcceleration;
          }
        }
      } else {
        // Assume full node mesh if no links specified
        var tree = (nDim === 1 ? binarytree(nodes, function (d) {
          return d.x;
        }) : nDim === 2 ? quadtree(nodes, function (d) {
          return d.x;
        }, function (d) {
          return d.y;
        }) : nDim === 3 ? octree(nodes, function (d) {
          return d.x;
        }, function (d) {
          return d.y;
        }, function (d) {
          return d.z;
        }) : null).visitAfter(accumulate);
        var etherStrength = alpha * strength();
        var _loop = function _loop() {
          var node = nodes[_i],
            nodeQ = charge(node);
          tree.visit(function (treeNode, x1, arg1, arg2, arg3) {
            if (!treeNode.value) return true;
            var x2 = [arg1, arg2, arg3][nDim - 1];
            var dx = treeNode.x - node.x,
              dy = treeNode.y - node.y || 0,
              dz = treeNode.z - node.z || 0,
              d = distance(dx, dy, dz);

            // Apply the Barnes-Hut approximation if possible.
            if ((x2 - x1) / d < theta) {
              if (d > 0) {
                applyAcceleration();
              }
              return true;
            }

            // Otherwise, process points directly.
            else if (treeNode.length || d === 0) return;
            do if (treeNode.data !== node) {
              applyAcceleration();
            } while (treeNode = treeNode.next);

            //

            function applyAcceleration() {
              var acceleration = signedCharge(treeNode.value, polarity(nodeQ, treeNode.value)) * etherStrength * distanceWeight(d);
              node.vx += dx / d * acceleration;
              if (nDim > 1) {
                node.vy += dy / d * acceleration;
              }
              if (nDim > 2) {
                node.vz += dz / d * acceleration;
              }
            }
          });
        };
        for (var _i = 0; _i < nodes.length; _i++) {
          _loop();
        }
      }

      //

      function accumulate(treeNode) {
        var localCharge = 0,
          q,
          c,
          weight = 0,
          x,
          y,
          z,
          i;

        // For internal nodes, accumulate forces from child tree-nodes (segments/quadrants/octants).
        if (treeNode.length) {
          for (x = y = z = i = 0; i < Math.pow(2, nDim); ++i) {
            if ((q = treeNode[i]) && (c = Math.abs(q.value))) {
              localCharge += q.value, weight += c, x += c * (q.x || 0), y += c * (q.y || 0), z += c * (q.z || 0);
            }
          }
          treeNode.x = x / weight;
          if (nDim > 1) {
            treeNode.y = y / weight;
          }
          if (nDim > 2) {
            treeNode.z = z / weight;
          }
        }

        // For leaf nodes, accumulate forces from coincident tree nodes.
        else {
          q = treeNode;
          q.x = q.data.x;
          if (nDim > 1) {
            q.y = q.data.y;
          }
          if (nDim > 2) {
            q.z = q.data.z;
          }
          do localCharge += charge(q.data); while (q = q.next);
        }
        treeNode.value = localCharge;
      }
      function signedCharge(q, polarity) {
        if (polarity === null) return q; // No change with null polarity
        return Math.abs(q) * (polarity ? 1 : -1);
      }
      function distance(x, y, z) {
        return Math.sqrt(x * x + y * y + z * z);
      }
    }
    function initialize() {
      var nodesById = {};
      nodes.forEach(function (node) {
        nodesById[id(node)] = node;
      });
      links.forEach(function (link) {
        if (_typeof(link.source) !== "object") link.source = nodesById[link.source] || link.source;
        if (_typeof(link.target) !== "object") link.target = nodesById[link.target] || link.target;
      });
    }
    force.initialize = function (initNodes) {
      nodes = initNodes;
      for (var _len = arguments.length, args = new Array(_len > 1 ? _len - 1 : 0), _key = 1; _key < _len; _key++) {
        args[_key - 1] = arguments[_key];
      }
      nDim = args.find(function (arg) {
        return [1, 2, 3].includes(arg);
      }) || 2;
      initialize();
    };
    force.links = function (_) {
      return arguments.length ? (links = _, initialize(), force) : links;
    };

    // Node id
    force.id = function (_) {
      return arguments.length ? (id = _, force) : id;
    };

    // Node capacity to attract (positive) or repel (negative)
    force.charge = function (_) {
      return arguments.length ? (charge = typeof _ === "function" ? _ : constant(+_), force) : charge;
    };

    // Link strength (ability of the medium to propagate charges)
    force.strength = function (_) {
      return arguments.length ? (strength = typeof _ === "function" ? _ : constant(+_), force) : strength;
    };

    // How force direction is determined (whether nodes should attract each other (boolean), or asymmetrical based on opposite node's charge sign (null))
    force.polarity = function (_) {
      return arguments.length ? (polarity = typeof _ === "function" ? _ : constant(+_), force) : polarity;
    };

    // How the force intensity relates to the distance between nodes
    force.distanceWeight = function (_) {
      return arguments.length ? (distanceWeight = _, force) : distanceWeight;
    };

    // Barnes-Hut approximation tetha threshold (for full-mesh mode)
    force.theta = function (_) {
      return arguments.length ? (theta = _, force) : theta;
    };
    return force;
  }

  exports.forceMagnetic = magnetic;

}));
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