Add _.partition.

lodash.js

@@ -1798,18 +1798,20 @@
     }
 
     /**
-     * Creates a function that aggregates a collection, creating an object composed
-     * of keys generated from the results of running each element of the collection
+     * Creates a function that aggregates a collection, creating an object or
+     * array composed from the results of running each element of the collection
      * through a callback. The given `setter` function sets the keys and values
-     * of the composed object.
+     * of the composed object or array.
      *
      * @private
      * @param {Function} setter The setter function.
+     * @param {boolean} [retArray=false] A flag to indicate that the aggregator
+     *  function should return an array.
      * @returns {Function} Returns the new aggregator function.
      */
-    function createAggregator(setter) {
+    function createAggregator(setter, retArray) {
       return function(collection, callback, thisArg) {
-        var result = {};
+        var result = retArray ? [[], []] : {};
 
         callback = lodash.createCallback(callback, thisArg, 3);
         if (isArray(collection)) {
@@ -4098,6 +4100,54 @@
       return result;
     }
 
+    /**
+     * Creates an array of grouped elements, the first of which contains elements
+     * the callback returns truey for, the second of which contains elements the
+     * callback returns falsey for. The callback is bound to `thisArg` and invoked
+     * with three arguments; (value, index|key, collection).
+     *
+     * If a property name is provided for `callback` the created "_.pluck" style
+     * callback will return the property value of the given element.
+     *
+     * If an object is provided for `callback` the created "_.where" style callback
+     * will return `true` for elements that have the properties of the given object,
+     * else `false`.
+     *
+     * @static
+     * @memberOf _
+     * @category Collections
+     * @param {Array|Object|string} collection The collection to iterate over.
+     * @param {Function|Object|string} [callback=identity] The function called
+     *  per iteration. If a property name or object is provided it will be used
+     *  to create a "_.pluck" or "_.where" style callback, respectively.
+     * @param {*} [thisArg] The `this` binding of `callback`.
+     * @returns {Array} Returns a new array of grouped elements.
+     * @example
+     *
+     * _.partition([1, 2, 3], function(num) { return num % 2; });
+     * // => [[1, 3], [2]]
+     *
+     * _.partition([1.2, 2.3, 3.4], function(num) { return this.floor(num) % 2; }, Math);
+     * // => [[1, 3], [2]]
+     *
+     * var characters = [
+     *   { 'name': 'barney',  'age': 36 },
+     *   { 'name': 'fred',    'age': 40, 'blocked': true },
+     *   { 'name': 'pebbles', 'age': 1 }
+     * ];
+     *
+     * // using "_.where" callback shorthand
+     * _.map(_.partition(characters, { 'age': 1 }), function(array) { return _.pluck(array, 'name'); });
+     * // => [['pebbles'], ['barney', 'fred']]
+     *
+     * // using "_.pluck" callback shorthand
+     * _.map(_.partition(characters, 'blocked'), function(array) { return _.pluck(array, 'name'); });
+     * // => [['fred'], ['barney', 'pebbles']]
+     */
+    var partition = createAggregator(function(result, value, key) {
+      result[key ? 0 : 1].push(value);
+    }, true);
+
     /**
      * Retrieves the value of a specified property from all elements in the collection.
      *
@@ -7452,6 +7502,7 @@
     lodash.pairs = pairs;
     lodash.partial = partial;
     lodash.partialRight = partialRight;
+    lodash.partition = partition;
     lodash.pick = pick;
     lodash.pluck = pluck;
     lodash.property = property;