diff -r efd9c589177a -r c0b4a8b5a012 toolkit/javascript/d3/src/layout/chord.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/javascript/d3/src/layout/chord.js	Thu Apr 10 14:20:23 2014 +0200
@@ -0,0 +1,153 @@
+d3.layout.chord = function() {
+  var chord = {},
+      chords,
+      groups,
+      matrix,
+      n,
+      padding = 0,
+      sortGroups,
+      sortSubgroups,
+      sortChords;
+
+  function relayout() {
+    var subgroups = {},
+        groupSums = [],
+        groupIndex = d3.range(n),
+        subgroupIndex = [],
+        k,
+        x,
+        x0,
+        i,
+        j;
+
+    chords = [];
+    groups = [];
+
+    // Compute the sum.
+    k = 0, i = -1; while (++i < n) {
+      x = 0, j = -1; while (++j < n) {
+        x += matrix[i][j];
+      }
+      groupSums.push(x);
+      subgroupIndex.push(d3.range(n));
+      k += x;
+    }
+
+    // Sort groups…
+    if (sortGroups) {
+      groupIndex.sort(function(a, b) {
+        return sortGroups(groupSums[a], groupSums[b]);
+      });
+    }
+
+    // Sort subgroups…
+    if (sortSubgroups) {
+      subgroupIndex.forEach(function(d, i) {
+        d.sort(function(a, b) {
+          return sortSubgroups(matrix[i][a], matrix[i][b]);
+        });
+      });
+    }
+
+    // Convert the sum to scaling factor for [0, 2pi].
+    // TODO Allow start and end angle to be specified.
+    // TODO Allow padding to be specified as percentage?
+    k = (2 * Math.PI - padding * n) / k;
+
+    // Compute the start and end angle for each group and subgroup.
+    // Note: Opera has a bug reordering object literal properties!
+    x = 0, i = -1; while (++i < n) {
+      x0 = x, j = -1; while (++j < n) {
+        var di = groupIndex[i],
+            dj = subgroupIndex[di][j],
+            v = matrix[di][dj],
+            a0 = x,
+            a1 = x += v * k;
+        subgroups[di + "-" + dj] = {
+          index: di,
+          subindex: dj,
+          startAngle: a0,
+          endAngle: a1,
+          value: v
+        };
+      }
+      groups.push({
+        index: di,
+        startAngle: x0,
+        endAngle: x,
+        value: (x - x0) / k
+      });
+      x += padding;
+    }
+
+    // Generate chords for each (non-empty) subgroup-subgroup link.
+    i = -1; while (++i < n) {
+      j = i - 1; while (++j < n) {
+        var source = subgroups[i + "-" + j],
+            target = subgroups[j + "-" + i];
+        if (source.value || target.value) {
+          chords.push(source.value < target.value
+              ? {source: target, target: source}
+              : {source: source, target: target});
+        }
+      }
+    }
+
+    if (sortChords) resort();
+  }
+
+  function resort() {
+    chords.sort(function(a, b) {
+      return sortChords(
+          (a.source.value + a.target.value) / 2,
+          (b.source.value + b.target.value) / 2);
+    });
+  }
+
+  chord.matrix = function(x) {
+    if (!arguments.length) return matrix;
+    n = (matrix = x) && matrix.length;
+    chords = groups = null;
+    return chord;
+  };
+
+  chord.padding = function(x) {
+    if (!arguments.length) return padding;
+    padding = x;
+    chords = groups = null;
+    return chord;
+  };
+
+  chord.sortGroups = function(x) {
+    if (!arguments.length) return sortGroups;
+    sortGroups = x;
+    chords = groups = null;
+    return chord;
+  };
+
+  chord.sortSubgroups = function(x) {
+    if (!arguments.length) return sortSubgroups;
+    sortSubgroups = x;
+    chords = null;
+    return chord;
+  };
+
+  chord.sortChords = function(x) {
+    if (!arguments.length) return sortChords;
+    sortChords = x;
+    if (chords) resort();
+    return chord;
+  };
+
+  chord.chords = function() {
+    if (!chords) relayout();
+    return chords;
+  };
+
+  chord.groups = function() {
+    if (!groups) relayout();
+    return groups;
+  };
+
+  return chord;
+};