Force-Directed Graph

This simple force-directed graph shows character co-occurence in Les Misérables. A physical simulation of charged particles and springs places related characters in closer proximity, while unrelated characters are farther apart. Layout algorithm inspired by Tim Dwyer and Thomas Jakobsen. Data based on character coappearence in Victor Hugo’s Les Misérables, compiled by Donald Knuth.

Source Code

 1 var width = 960,
 2     height = 500;
 3 
 4 var color = d3.scale.category20();
 5 
 6 var force = d3.layout.force()
 7     .charge(-120)
 8     .linkDistance(30)
 9     .size([width, height]);
10 
11 var svg = d3.select("#chart").append("svg")
12     .attr("width", width)
13     .attr("height", height);
14 
15 d3.json("miserables.json", function(json) {
16   force
17       .nodes(json.nodes)
18       .links(json.links)
19       .start();
20 
21   var link = svg.selectAll("line.link")
22       .data(json.links)
23     .enter().append("line")
24       .attr("class", "link")
25       .style("stroke-width", function(d) { return Math.sqrt(d.value); });
26 
27   var node = svg.selectAll("circle.node")
28       .data(json.nodes)
29     .enter().append("circle")
30       .attr("class", "node")
31       .attr("r", 5)
32       .style("fill", function(d) { return color(d.group); })
33       .call(force.drag);
34 
35   node.append("title")
36       .text(function(d) { return d.name; });
37 
38   force.on("tick", function() {
39     link.attr("x1", function(d) { return d.source.x; })
40         .attr("y1", function(d) { return d.source.y; })
41         .attr("x2", function(d) { return d.target.x; })
42         .attr("y2", function(d) { return d.target.y; });
43 
44     node.attr("cx", function(d) { return d.x; })
45         .attr("cy", function(d) { return d.y; });
46   });
47 });