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

node {
 stroke: #fff;
 stroke-width: 1.5px;
}

link {
 stroke: #999;
 stroke-opacity: .6;
}

</style>
<body>
<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.5/d3.min.js"></script>
<script>

var width = 960,
   height = 500;

var color = d3.scale.category20();

var force = d3.layout.force()
   .charge(-120)
   .linkDistance(30)
   .size([width, height]);

var svg = d3.select("body").append("svg")
   .attr("width", width)
   .attr("height", height);

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

 force
     .nodes(graph.nodes)
     .links(graph.links)
     .start();

 var link = svg.selectAll(".link")
     .data(graph.links)
   .enter().append("line")
     .attr("class", "link")
     .style("stroke-width", function(d) { return Math.sqrt(d.value); });

 var node = svg.selectAll(".node")
     .data(graph.nodes)
   .enter().append("circle")
     .attr("class", "node")
     .attr("r", 5)
     .style("fill", function(d) { return color(d.group); })
     .call(force.drag);

 node.append("title")
     .text(function(d) { return d.name; });

 force.on("tick", function() {
   link.attr("x1", function(d) { return d.source.x; })
       .attr("y1", function(d) { return d.source.y; })
       .attr("x2", function(d) { return d.target.x; })
       .attr("y2", function(d) { return d.target.y; });

   node.attr("cx", function(d) { return d.x; })
       .attr("cy", function(d) { return d.y; });
 });
});

</script>