Hierarchical Edge Bundling

An implementation of Danny Holten's hierarchical edge bundling algorithm in D3, showing dependencies between classes in a software class hierarchy. Dependencies are bundled according to the parent packages. This example uses two layouts: a radial d3.layout.cluster to position the tree nodes, and d3.layout.bundle to group the dependencies into spline bundles. Thanks to Jason Davies for contributing the layout implementation!

Compare to this treemap layout.

See also the interactive version with link highlighting!

forked from mbostock's block: Hierarchical Edge Bundling

<!DOCTYPE html>
<style>

.node {
  font: 10px sans-serif;
}

.link {
  stroke: steelblue;
  stroke-opacity: 0.5;
  fill: none;
  pointer-events: none;
}

</style>
<body>
<script src="https://d3js.org/d3.v4.min.js"></script>
<script>

var diameter = 960,
    radius = diameter / 2,
    innerRadius = radius - 120;

var cluster = d3.cluster()
    .size([360, innerRadius]);

var line = d3.radialLine()
    .curve(d3.curveBundle.beta(0.85))
    .radius(function(d) { return d.y; })
    .angle(function(d) { return d.x / 180 * Math.PI; });

var svg = d3.select("body").append("svg")
    .attr("width", diameter)
    .attr("height", diameter)
  .append("g")
    .attr("transform", "translate(" + radius + "," + radius + ")");

var link = svg.append("g").selectAll(".link"),
    node = svg.append("g").selectAll(".node");

d3.json("flare.json", function(error, classes) {
  if (error) throw error;

var root = packageHierarchy(classes)
      .sum(function(d) { return d.size; });

cluster(root);

link = link
    .data(packageImports(root.leaves()))
    .enter().append("path")
      .each(function(d) { d.source = d[0], d.target = d[d.length - 1]; })
      .attr("class", "link")
      .attr("d", line);

node = node
    .data(root.leaves())
    .enter().append("text")
      .attr("class", "node")
      .attr("dy", "0.31em")
      .attr("transform", function(d) { return "rotate(" + (d.x - 90) + ")translate(" + (d.y + 8) + ",0)" + (d.x < 180 ? "" : "rotate(180)"); })
      .attr("text-anchor", function(d) { return d.x < 180 ? "start" : "end"; })
      .text(function(d) { return d.data.key; });
});

// Lazily construct the package hierarchy from class names.
function packageHierarchy(classes) {
  var map = {};

classes.forEach(function(d) {
    find(d.name, d);
  });

return d3.hierarchy(map[""]);
}

// Return a list of imports for the given array of nodes.
function packageImports(nodes) {
  var map = {},
      imports = [];

// Compute a map from name to node.
  nodes.forEach(function(d) {
    map[d.data.name] = d;
  });

// For each import, construct a link from the source to target node.
  nodes.forEach(function(d) {
    if (d.data.imports) d.data.imports.forEach(function(i) {
      imports.push(map[d.data.name].path(map[i]));
    });
  });

return imports;
}

</script>

https://d3js.org/d3.v4.min.js