Graph Rollup

The d3.rollup plugin implements the “PivotGraph” technique for collapsing large graphs along categorical dimensions, as described by Martin Wattenberg in Visual Exploration of Multivariate Graphs.

<!DOCTYPE html>
<meta charset="utf-8">
<title>PivotGraph (Rollup) Layout</title>
<style>

body {
  font-family: sans-serif;
  font-size: 10px;
}

.link {
  fill: none;
  stroke: #000;
  stroke-opacity: .25;
}

.node {
  fill: #fff;
  stroke: steelblue;
}

.axis path,
.axis line {
  display: none;
}

</style>
<body>
<script src="//d3js.org/d3.v3.min.js"></script>
<script src="d3.rollup.min.js"></script>
<script>

var margin = {top: 90, right: 240, bottom: 90, left: 240},
    width = 960 - margin.left - margin.right,
    height = 500 - margin.top - margin.bottom;

function fx(d) { return d.gender; }
function fy(d) { return d.group; }

var x = d3.scale.ordinal()
    .rangePoints([6, width - 6]);

var y = d3.scale.ordinal()
    .rangePoints([6, height - 6]);

var xAxis = d3.svg.axis()
    .scale(x)
    .orient("top");

var yAxis = d3.svg.axis()
    .scale(y)
    .orient("left");

var rollup = d3.rollup()
    .x(function(d) { return x(fx(d)); })
    .y(function(d) { return y(fy(d)); });

var svg = d3.select("body").append("svg")
    .attr("width", width + margin.left + margin.right)
    .attr("height", height + margin.top + margin.bottom)
  .append("g")
    .attr("transform", "translate(" + margin.left + "," + margin.top + ")");

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

x.domain(social.nodes.map(fx));
  y.domain(social.nodes.map(fy));
  var graph = rollup(social);

svg.selectAll(".link")
      .data(graph.links)
    .enter().append("path")
      .attr("class", "link")
      .attr("d", function(d) {
        var sx = d.source.x, sy = d.source.y,
            tx = d.target.x, ty = d.target.y,
            dx = tx - sx, dy = ty - sy,
            dr = 2 * Math.sqrt(dx * dx + dy * dy);
        return "M" + sx + "," + sy + "A" + dr + "," + dr + " 0 0,1 " + tx + "," + ty;
      })
      .style("stroke-width", function(d) { return d.value * 4; });

svg.selectAll(".node")
      .data(graph.nodes)
    .enter().append("circle")
      .attr("class", "node")
      .attr("r", function(d) { return Math.sqrt(d.nodes.length * 40); })
      .attr("cx", function(d) { return d.x; })
      .attr("cy", function(d) { return d.y; });

svg.append("g")
      .attr("class", "x axis")
      .call(xAxis);

svg.append("g")
      .attr("class", "y axis")
      .call(yAxis);
});

</script>

https://d3js.org/d3.v3.min.js