Radial Cluster Dendrogram

A dendrogram is a node-link diagram that places leaf nodes of the tree at the same depth. In this example, the classes (leaf nodes) are aligned on the right edge, with the packages (internal nodes) to the left. Data shows the Flare class hierarchy, courtesy Jeff Heer.

Compare to this Cartesian layout.

<!DOCTYPE html>
<meta charset="utf-8">
<style>

.node circle {
  fill: #999;
}

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

.node--internal circle {
  fill: #555;
}

.node--internal text {
  text-shadow: 0 1px 0 #fff, 0 -1px 0 #fff, 1px 0 0 #fff, -1px 0 0 #fff;
}

.link {
  fill: none;
  stroke: #555;
  stroke-opacity: 0.4;
  stroke-width: 1.5px;
}

</style>
<svg width="960" height="950"></svg>
<script src="https://d3js.org/d3.v4.min.js"></script>
<script>

var svg = d3.select("svg"),
    width = +svg.attr("width"),
    height = +svg.attr("height"),
    g = svg.append("g").attr("transform", "translate(" + (width / 2 - 15) + "," + (height / 2 + 25) + ")");

var stratify = d3.stratify()
    .parentId(function(d) { return d.id.substring(0, d.id.lastIndexOf(".")); });

var tree = d3.cluster()
    .size([360, 390])
    .separation(function(a, b) { return (a.parent == b.parent ? 1 : 2) / a.depth; });

d3.csv("flare.csv", function(error, data) {
  if (error) throw error;

var root = tree(stratify(data)
      .sort(function(a, b) { return (a.height - b.height) || a.id.localeCompare(b.id); }));

var link = g.selectAll(".link")
    .data(root.descendants().slice(1))
    .enter().append("path")
      .attr("class", "link")
      .attr("d", function(d) {
        return "M" + project(d.x, d.y)
            + "C" + project(d.x, (d.y + d.parent.y) / 2)
            + " " + project(d.parent.x, (d.y + d.parent.y) / 2)
            + " " + project(d.parent.x, d.parent.y);
      });

var node = g.selectAll(".node")
    .data(root.descendants())
    .enter().append("g")
      .attr("class", function(d) { return "node" + (d.children ? " node--internal" : " node--leaf"); })
      .attr("transform", function(d) { return "translate(" + project(d.x, d.y) + ")"; });

node.append("circle")
      .attr("r", 2.5);

node.append("text")
      .attr("dy", ".31em")
      .attr("x", function(d) { return d.x < 180 === !d.children ? 6 : -6; })
      .style("text-anchor", function(d) { return d.x < 180 === !d.children ? "start" : "end"; })
      .attr("transform", function(d) { return "rotate(" + (d.x < 180 ? d.x - 90 : d.x + 90) + ")"; })
      .text(function(d) { return d.id.substring(d.id.lastIndexOf(".") + 1); });
});

function project(x, y) {
  var angle = (x - 90) / 180 * Math.PI, radius = y;
  return [radius * Math.cos(angle), radius * Math.sin(angle)];
}

</script>

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