1  var baseAssignValue = require('./_baseAssignValue'),
 2      createAggregator = require('./_createAggregator');
 3  
 4  /** Used for built-in method references. */
 5  var objectProto = Object.prototype;
 6  
 7  /** Used to check objects for own properties. */
 8  var hasOwnProperty = objectProto.hasOwnProperty;
 9  
10  /**
11   * Creates an object composed of keys generated from the results of running
12   * each element of `collection` thru `iteratee`. The order of grouped values
13   * is determined by the order they occur in `collection`. The corresponding
14   * value of each key is an array of elements responsible for generating the
15   * key. The iteratee is invoked with one argument: (value).
16   *
17   * @static
18   * @memberOf _
19   * @since 0.1.0
20   * @category Collection
21   * @param {Array|Object} collection The collection to iterate over.
22   * @param {Function} [iteratee=_.identity] The iteratee to transform keys.
23   * @returns {Object} Returns the composed aggregate object.
24   * @example
25   *
26   * _.groupBy([6.1, 4.2, 6.3], Math.floor);
27   * // => { '4': [4.2], '6': [6.1, 6.3] }
28   *
29   * // The `_.property` iteratee shorthand.
30   * _.groupBy(['one', 'two', 'three'], 'length');
31   * // => { '3': ['one', 'two'], '5': ['three'] }
32   */
33  var groupBy = createAggregator(function(result, value, key) {
34    if (hasOwnProperty.call(result, key)) {
35      result[key].push(value);
36    } else {
37      baseAssignValue(result, key, [value]);
38    }
39  });
40  
41  module.exports = groupBy;