Force-Directed States of America by zanarmstrong

Click and drag to move states around.

So, what happens when you use the Delaunay triangulation to compute links between the centroids of the lower 48 United States of America? And then you simulate the whole thing as a force-directed graph? This, it turns out! Built with D3.

forked from mbostock‘s block: Force-Directed States of America

index.html

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

path {
  fill: #ddd;
  fill-opacity: .8;
  stroke: #fff;
  stroke-width: 1.5px;
}

line {
  stroke: #999;
}

</style>
<body>
<script src="//d3js.org/d3.v3.min.js"></script>
<script src="//d3js.org/topojson.v1.min.js"></script>
<script>

var width = 960,
    height = 500;

var path = d3.geo.path(),
    force = d3.layout.force().size([width, height]);

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

d3.json("https://gist.githubusercontent.com/mbostock/4090846/raw/d534aba169207548a8a3d670c9c2cc719ff05c47/us.json", function(error, us) {
  if (error) throw error;

  var states = topojson.feature(us, us.objects.states),
      nodes = [],
      links = [];

  states.features.forEach(function(d, i) {
    if (d.id === 2 || d.id === 15 || d.id === 72) return; // lower 48
    var centroid = path.centroid(d);
    if (centroid.some(isNaN)) return;
    centroid.x = centroid[0];
    centroid.y = centroid[1];
    centroid.feature = d;
    nodes.push(centroid);
  });

  d3.geom.voronoi().links(nodes).forEach(function(link) {
    var dx = link.source.x - link.target.x,
        dy = link.source.y - link.target.y;
    link.distance = Math.sqrt(dx * dx + dy * dy) + 5;
    links.push(link);
  });

  force
      .gravity(0)
      .nodes(nodes)
      .links(links)
      .linkDistance(function(d) { return d.distance; })
      .start();

  var link = svg.selectAll("line")
      .data(links)
    .enter().append("line")
      .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; });

  var node = svg.selectAll("g")
      .data(nodes)
    .enter().append("g")
      .attr("transform", function(d) { return "translate(" + -d.x + "," + -d.y + ")"; })
      .call(force.drag)
    .append("path")
      .attr("transform", function(d) { return "translate(" + d.x + "," + d.y + ")"; })
      .attr("d", function(d) { return path(d.feature); })

  force.on("tick", function(e) {
    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 + ")scale(.5)";
    });
  });
  
});

</script>