diff -r efd9c589177a -r c0b4a8b5a012 toolkit/javascript/d3/examples/cartogram/demers.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/javascript/d3/examples/cartogram/demers.js	Thu Apr 10 14:20:23 2014 +0200
@@ -0,0 +1,79 @@
+// Ratio of Obese (BMI >= 30) in U.S. Adults, CDC 2008
+var data = [
+  , .187, .198, , .133, .175, .151, , .1, .125, .171, , .172, .133, , .108,
+  .142, .167, .201, .175, .159, .169, .177, .141, .163, .117, .182, .153, .195,
+  .189, .134, .163, .133, .151, .145, .13, .139, .169, .164, .175, .135, .152,
+  .169, , .132, .167, .139, .184, .159, .14, .146, .157, , .139, .183, .16, .143
+];
+
+var color = d3.scale.linear()
+    .domain([d3.min(data), d3.max(data)])
+    .range(["#aad", "#556"]); 
+
+var force = d3.layout.force()
+    .charge(0)
+    .gravity(0)
+    .size([960, 500]);
+
+var svg = d3.select("#chart").append("svg:svg");
+
+d3.json("../data/us-state-centroids.json", function(states) {
+  var project = d3.geo.albersUsa(),
+      idToNode = {},
+      links = [],
+      nodes = states.features.map(function(d) {
+    var xy = project(d.geometry.coordinates);
+    return idToNode[d.id] = {
+      x: xy[0],
+      y: xy[1],
+      gravity: {x: xy[0], y: xy[1]},
+      r: Math.sqrt(data[+d.id] * 2500),
+      value: data[+d.id]
+    };
+  });
+
+  force
+      .nodes(nodes)
+      .links(links)
+      .start()
+      .on("tick", function(e) {
+    var k = e.alpha * .5,
+        kg = k * .1;
+    nodes.forEach(function(a, i) {
+      // Apply gravity forces.
+      a.x += (a.gravity.x - a.x) * kg;
+      a.y += (a.gravity.y - a.y) * kg;
+      nodes.slice(i + 1).forEach(function(b) {
+        // Check for collision
+        var dx = a.x - b.x,
+            dy = a.y - b.y,
+            d = a.r + b.r,
+            lx = Math.abs(dx),
+            ly = Math.abs(dy);
+        if (lx < d && ly < d) {
+          lx = (lx - d) / lx * k;
+          ly = (ly - d) / ly * k;
+          dx *= lx;
+          dy *= ly;
+          a.x -= dx;
+          a.y -= dy;
+          b.x += dx;
+          b.y += dy;
+        }
+      });
+    });
+
+    svg.selectAll("rect")
+        .attr("x", function(d) { return d.x - d.r; })
+        .attr("y", function(d) { return d.y - d.r; });
+  });
+
+  svg.selectAll("rect")
+      .data(nodes)
+    .enter().append("svg:rect")
+      .style("fill", function(d) { return color(d.value); })
+      .attr("x", function(d) { return d.x - d.r; })
+      .attr("y", function(d) { return d.y - d.r; })
+      .attr("width", function(d) { return d.r * 2; })
+      .attr("height", function(d) { return d.r * 2; });
+});