Break out _.sampleSize and _.shuffle into array helpers.

lodash.js

@@ -2392,6 +2392,31 @@
       return length ? array[baseRandom(0, length - 1)] : undefined;
     }
 
+    /**
+     * A specialized version of `_.sampleSize` for arrays.
+     *
+     * @private
+     * @param {Array} array The array to sample.
+     * @param {number} n The number of elements to sample.
+     * @returns {Array} Returns the random elements.
+     */
+    function arraySampleSize(array, n) {
+      var result = arrayShuffle(array);
+      result.length = baseClamp(n, 0, result.length);
+      return result;
+    }
+
+    /**
+     * A specialized version of `_.shuffle` for arrays.
+     *
+     * @private
+     * @param {Array} array The array to shuffle.
+     * @returns {Array} Returns the new shuffled array.
+     */
+    function arrayShuffle(array) {
+      return shuffleSelf(copyArray(array));
+    }
+
     /**
      * Used by `_.defaults` to customize its `_.assignIn` use.
      *
@@ -6514,6 +6539,28 @@
       };
     }
 
+    /**
+     * A specialized version of `arrayShuffle` which mutates `array`.
+     *
+     * @private
+     * @param {Array} array The array to shuffle.
+     * @returns {Array} Returns `array`.
+     */
+    function shuffleSelf(array) {
+      var index = -1,
+          length = array.length,
+          lastIndex = length - 1;
+
+      while (++index < length) {
+        var rand = baseRandom(index, lastIndex),
+            value = array[rand];
+
+        array[rand] = array[index];
+        array[index] = value;
+      }
+      return array;
+    }
+
     /**
      * Converts `string` to a property path array.
      *
@@ -9612,25 +9659,12 @@
      * // => [2, 3, 1]
      */
     function sampleSize(collection, n, guard) {
-      var index = -1,
-          result = toArray(collection),
-          length = result.length,
-          lastIndex = length - 1;
-
       if ((guard ? isIterateeCall(collection, n, guard) : n === undefined)) {
         n = 1;
       } else {
-        n = baseClamp(toInteger(n), 0, length);
+        n = toInteger(n);
       }
-      while (++index < n) {
+      return arraySampleSize(isArrayLike(collection) ? collection : values(collection), n);
-        var rand = baseRandom(index, lastIndex),
-            value = result[rand];
-
-        result[rand] = result[index];
-        result[index] = value;
-      }
-      result.length = n;
-      return result;
     }
 
     /**
@@ -9649,7 +9683,10 @@
      * // => [4, 1, 3, 2]
      */
     function shuffle(collection) {
-      return sampleSize(collection, MAX_ARRAY_LENGTH);
+      return shuffleSelf(isArrayLike(collection)
+        ? copyArray(collection)
+        : values(collection)
+      );
     }
 
     /**