D3 force layout: How do I set the size of every node?

Question

I'm using the amazing D3JS to build a graph. The graph is rendered, but I want my nodes to have each one its size.

The data is of this form :

{source: "Antony Hoppkins", target: "Woody Allen", value: 3}

Here's the code :

var links = graph.links;
var nodes = {};

links.forEach(function(link) {
  link.source = nodes[link.source] || (nodes[link.source] = {name: link.source});
  link.target = nodes[link.target] || (nodes[link.target] = {name: link.target});
});

var width = 1200,
    height = 1500;

var force = d3.layout.force()
    .nodes(d3.values(nodes))
    .links(links)
    .size([width, height])
    .linkDistance(50)
    .charge(-200)
    .on("tick", tick)
    .start();

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

var link = svg.selectAll(".link")
    .data(force.links())
  .enter().append("line")
    .attr("class", "link");

var node = svg.selectAll(".node")
    .data(force.nodes())
  .enter().append("g")
    .attr("class", "node")
    .style("stroke-width", function(d) { return (d.value)*5; })
    .on("mouseover", mouseover)
    .on("mouseout", mouseout)
    .call(force.drag);

node.append("circle")
    .attr("r", 5);

node.append("text")
    .attr("x", 12)
    .attr("dy", ".35em")
    .text(function(d) { return d.name; });

function tick() {
  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("transform", function(d) { return "translate(" + d.x + "," + d.y + ")"; });
}

function mouseover() {
  d3.select(this).select("circle").transition()
      .duration(750)
      .attr("r", 10)
      ;
}

function mouseout() {
  d3.select(this).select("circle").transition()
      .duration(750)
      .attr("r", 5)
      ;
}

Any thoughts ?

Answer 1

I'm assuming that you want to set the size of each node (i.e. radius) according to .value. You do this like this:

node.append("circle")
  .attr("r", function(d) { return d.value * 3; });

You can obviously adjust the factor, or use a scale instead.