Merge branch 'shuffle-subset' of github.com:PrajitR/d3 into shuffle-subset

d3.js

@@ -163,11 +163,15 @@
       return d3_ascending(f(d), x);
     } : f);
   };
-  d3.shuffle = function(array) {
-    var m = array.length, t, i;
+  d3.shuffle = function(array, i0, i1) {
+    if ((m = arguments.length) < 3) {
+      i1 = array.length;
+      if (m < 2) i0 = 0;
+    }
+    var m = i1 - i0, t, i;
     while (m) {
       i = Math.random() * m-- | 0;
-      t = array[m], array[m] = array[i], array[i] = t;
+      t = array[m + i0], array[m + i0] = array[i + i0], array[i + i0] = t;
     }
     return array;
   };

src/arrays/shuffle.js

@@ -1,8 +1,9 @@
-d3.shuffle = function(array) {
-  var m = array.length, t, i;
+d3.shuffle = function(array, i0, i1) {
+  if ((m = arguments.length) < 3) { i1 = array.length; if (m < 2) i0 = 0; }
+  var m = i1 - i0, t, i;
   while (m) {
     i = Math.random() * m-- | 0;
-    t = array[m], array[m] = array[i], array[i] = t;
+    t = array[m + i0], array[m + i0] = array[i + i0], array[i + i0] = t;
   }
   return array;
 };

test/arrays/shuffle-test.js

@@ -0,0 +1,43 @@
+var vows = require("vows"),
+    load = require("../load"),
+    assert = require("../assert"),
+    seedrandom = require("seedrandom");
+
+var suite = vows.describe("d3.shuffle");
+
+var _random;
+
+suite.addBatch({
+  "shuffle": {
+    topic: load("arrays/shuffle").sandbox({Math: Math}).expression("d3.shuffle"),
+    "(using seedrandom)": {
+      topic: function(random) {
+        _random = Math.random;
+        return random;
+      },
+      "shuffles an array in-place": function(shuffle) {
+        Math.seedrandom("a random seed.");
+        var array = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
+        assert.strictEqual(shuffle(array), array);
+        assert.deepEqual(array, [6, 4, 7, 9, 3, 1, 5, 8, 0, 2]);
+      },
+      "shuffles a subset of an array from the specified start": function(shuffle) {
+        Math.seedrandom("a random seed.");
+        var array = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
+        assert.strictEqual(shuffle(array, 4), array);
+        assert.deepEqual(array, [0, 1, 2, 3, 9, 7, 6, 8, 4, 5]);
+      },
+      "shuffles a subset of an array between the specified start and end": function(shuffle) {
+        Math.seedrandom("a random seed.");
+        var array = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
+        assert.strictEqual(shuffle(array, 3, 8), array);
+        assert.deepEqual(array, [0, 1, 2, 5, 7, 6, 3, 4, 8, 9]);
+      },
+      teardown: function() {
+        Math.random = _random;
+      }
+    }
+  }
+});
+
+suite.export(module);

test/math/random-test.js

@@ -5,6 +5,8 @@ var vows = require("vows"),
 
 var suite = vows.describe("d3.random");
 
+var _random;
+
 // Testing a random number generator is a bit more complicated than testing
 // deterministic code, so we use different techniques.
 //