Add d3.shuffle. Fixes #948.

Makefile

@@ -49,6 +49,7 @@ d3.core.js: \
 	src/core/number.js \
 	src/core/sum.js \
 	src/core/quantile.js \
+	src/core/shuffle.js \
 	src/core/transpose.js \
 	src/core/zip.js \
 	src/core/bisect.js \

d3.js

@@ -237,6 +237,14 @@
     var H = (values.length - 1) * p + 1, h = Math.floor(H), v = values[h - 1], e = H - h;
     return e ? v + e * (values[h] - v) : v;
   };
+  d3.shuffle = function(array) {
+    var m = array.length, t, i;
+    while (m) {
+      i = Math.random() * m-- | 0;
+      t = array[m], array[m] = array[i], array[i] = t;
+    }
+    return array;
+  };
   d3.transpose = function(matrix) {
     return d3.zip.apply(d3, matrix);
   };

src/core/shuffle.js

@@ -0,0 +1,8 @@
+d3.shuffle = function(array) {
+  var m = array.length, t, i;
+  while (m) {
+    i = Math.random() * m-- | 0;
+    t = array[m], array[m] = array[i], array[i] = t;
+  }
+  return array;
+};