https://browser-update.org/static/sankey.js

1d3.sankey = function() {
2  var sankey = {},
3      nodeWidth = 24,
4      nodePadding = 8,
5      size = [1, 1],
6      nodes = [],
7      links = [];
8
9  sankey.nodeWidth = function(_) {
10    if (!arguments.length) return nodeWidth;
11    nodeWidth = +_;
12    return sankey;
13  };
14
15  sankey.nodePadding = function(_) {
16    if (!arguments.length) return nodePadding;
17    nodePadding = +_;
18    return sankey;
19  };
20
21  sankey.nodes = function(_) {
22    if (!arguments.length) return nodes;
23    nodes = _;
24    return sankey;
25  };
26
27  sankey.links = function(_) {
28    if (!arguments.length) return links;
29    links = _;
30    return sankey;
31  };
32
33  sankey.size = function(_) {
34    if (!arguments.length) return size;
35    size = _;
36    return sankey;
37  };
38
39  sankey.layout = function(iterations) {
40    computeNodeLinks();
41    computeNodeValues();
42    computeNodeBreadths();
43    computeNodeDepths(iterations);
44    computeLinkDepths();
45    return sankey;
46  };
47
48  sankey.relayout = function() {
49    computeLinkDepths();
50    return sankey;
51  };
52
53  sankey.link = function() {
54    var curvature = .5;
55
56    function link(d) {
57      var x0 = d.source.x + d.source.dx,
58          x1 = d.target.x,
59          xi = d3.interpolateNumber(x0, x1),
60          x2 = xi(curvature),
61          x3 = xi(1 - curvature),
62          y0 = d.source.y + d.sy + d.dy / 2,
63          y1 = d.target.y + d.ty + d.dy / 2;
64      return "M" + x0 + "," + y0
65           + "C" + x2 + "," + y0
66           + " " + x3 + "," + y1
67           + " " + x1 + "," + y1;
68    }
69
70    link.curvature = function(_) {
71      if (!arguments.length) return curvature;
72      curvature = +_;
73      return link;
74    };
75
76    return link;
77  };
78
79  // Populate the sourceLinks and targetLinks for each node.
80  // Also, if the source and target are not objects, assume they are indices.
81  function computeNodeLinks() {
82    nodes.forEach(function(node) {
83      node.sourceLinks = [];
84      node.targetLinks = [];
85    });
86    links.forEach(function(link) {
87      var source = link.source,
88          target = link.target;
89      if (typeof source === "number") source = link.source = nodes[link.source];
90      if (typeof target === "number") target = link.target = nodes[link.target];
91      source.sourceLinks.push(link);
92      target.targetLinks.push(link);
93    });
94  }
95
96  // Compute the value (size) of each node by summing the associated links.
97  function computeNodeValues() {
98    nodes.forEach(function(node) {
99      node.value = Math.max(
100        d3.sum(node.sourceLinks, value),
101        d3.sum(node.targetLinks, value)
102      );
103    });
104  }
105
106  // Iteratively assign the breadth (x-position) for each node.
107  // Nodes are assigned the maximum breadth of incoming neighbors plus one;
108  // nodes with no incoming links are assigned breadth zero, while
109  // nodes with no outgoing links are assigned the maximum breadth.
110  function computeNodeBreadths() {
111    var remainingNodes = nodes,
112        nextNodes,
113        x = 0;
114
115    while (remainingNodes.length) {
116      nextNodes = [];
117      remainingNodes.forEach(function(node) {
118        node.x = x;
119        node.dx = nodeWidth;
120        node.sourceLinks.forEach(function(link) {
121          nextNodes.push(link.target);
122        });
123      });
124      remainingNodes = nextNodes;
125      ++x;
126    }
127
128    //
129    moveSinksRight(x);
130    scaleNodeBreadths((width - nodeWidth) / (x - 1));
131  }
132
133  function moveSourcesRight() {
134    nodes.forEach(function(node) {
135      if (!node.targetLinks.length) {
136        node.x = d3.min(node.sourceLinks, function(d) { return d.target.x; }) - 1;
137      }
138    });
139  }
140
141  function moveSinksRight(x) {
142    nodes.forEach(function(node) {
143      if (!node.sourceLinks.length) {
144        node.x = x - 1;
145      }
146    });
147  }
148
149  function scaleNodeBreadths(kx) {
150    nodes.forEach(function(node) {
151      node.x *= kx;
152    });
153  }
154
155  function computeNodeDepths(iterations) {
156    var nodesByBreadth = d3.nest()
157        .key(function(d) { return d.x; })
158        .sortKeys(d3.ascending)

159        .entries(nodes)
160        .map(function(d) { return d.values; });
161
162    //
163    initializeNodeDepth();
164    resolveCollisions();
165    for (var alpha = 1; iterations > 0; --iterations) {
166      relaxRightToLeft(alpha *= .99);
167      resolveCollisions();
168      relaxLeftToRight(alpha);
169      resolveCollisions();
170    }
171
172    function initializeNodeDepth() {
173      var ky = d3.min(nodesByBreadth, function(nodes) {
174        return (size[1] - (nodes.length - 1) * nodePadding) / d3.sum(nodes, value);
175      });
176
177      nodesByBreadth.forEach(function(nodes) {
178        nodes.forEach(function(node, i) {
179          node.y = i;
180          node.dy = node.value * ky;
181        });
182      });
183
184      links.forEach(function(link) {
185        link.dy = link.value * ky;
186      });
187    }
188
189    function relaxLeftToRight(alpha) {
190      nodesByBreadth.forEach(function(nodes, breadth) {
191        nodes.forEach(function(node) {
192          if (node.targetLinks.length) {
193            var y = d3.sum(node.targetLinks, weightedSource) / d3.sum(node.targetLinks, value);
194            node.y += (y - center(node)) * alpha;
195          }
196        });
197      });
198
199      function weightedSource(link) {
200        return center(link.source) * link.value;
201      }
202    }
203
204    function relaxRightToLeft(alpha) {
205      nodesByBreadth.slice().reverse().forEach(function(nodes) {
206        nodes.forEach(function(node) {
207          if (node.sourceLinks.length) {
208            var y = d3.sum(node.sourceLinks, weightedTarget) / d3.sum(node.sourceLinks, value);
209            node.y += (y - center(node)) * alpha;
210          }
211        });
212      });
213
214      function weightedTarget(link) {
215        return center(link.target) * link.value;
216      }
217    }
218
219    function resolveCollisions() {
220      nodesByBreadth.forEach(function(nodes) {
221        var node,
222            dy,
223            y0 = 0,
224            n = nodes.length,
225            i;
226
227        // Push any overlapping nodes down.
228        nodes.sort(ascendingDepth);
229        for (i = 0; i < n; ++i) {
230          node = nodes[i];
231          dy = y0 - node.y;
232          if (dy > 0) node.y += dy;
233          y0 = node.y + node.dy + nodePadding;
234        }
235
236        // If the bottommost node goes outside the bounds, push it back up.
237        dy = y0 - nodePadding - size[1];
238        if (dy > 0) {
239          y0 = node.y -= dy;
240
241          // Push any overlapping nodes back up.
242          for (i = n - 2; i >= 0; --i) {
243            node = nodes[i];
244            dy = node.y + node.dy + nodePadding - y0;
245            if (dy > 0) node.y -= dy;
246            y0 = node.y;
247          }
248        }
249      });
250    }
251
252    function ascendingDepth(a, b) {
253      return a.y - b.y;
254    }
255  }
256
257  function computeLinkDepths() {
258    nodes.forEach(function(node) {
259      node.sourceLinks.sort(ascendingTargetDepth);
260      node.targetLinks.sort(ascendingSourceDepth);
261    });
262    nodes.forEach(function(node) {
263      var sy = 0, ty = 0;
264      node.sourceLinks.forEach(function(link) {
265        link.sy = sy;
266        sy += link.dy;
267      });
268      node.targetLinks.forEach(function(link) {
269        link.ty = ty;
270        ty += link.dy;
271      });
272    });
273
274    function ascendingSourceDepth(a, b) {
275      return a.source.y - b.source.y;
276    }
277
278    function ascendingTargetDepth(a, b) {
279      return a.target.y - b.target.y;
280    }
281  }
282
283  function center(node) {
284    return node.y + node.dy / 2;
285  }
286
287  function value(link) {
288    return link.value;
289  }
290
291  return sankey;
292};