From 3408db91b6beecb10bd1f2dd8abbdbbf352521fe Mon Sep 17 00:00:00 2001
From: Agus Pina <aguspina87@gmail.com>
Date: Tue, 10 Nov 2015 16:21:01 -0300
Subject: [PATCH] Add `_.mean`.

---
 lib/fp/mapping.js | 12 ++++++------
 lodash.js         | 49 +++++++++++++++++++++++++++++++----------------
 test/test.js      | 15 ++++++++++++++-
 3 files changed, 52 insertions(+), 24 deletions(-)

diff --git a/lib/fp/mapping.js b/lib/fp/mapping.js
index 6286eacfc..a30bf9349 100644
--- a/lib/fp/mapping.js
+++ b/lib/fp/mapping.js
@@ -84,12 +84,12 @@ module.exports = {
       'dropWhile,endsWith,every,extend,filter,find,find,findIndex,findKey,findLast,' +
       'findLastIndex,findLastKey,forEach,forEachRight,forIn,forInRight,forOwn,' +
       'forOwnRight,get,groupBy,includes,indexBy,indexOf,intersection,invoke,isMatch,' +
-      'lastIndexOf,map,mapKeys,mapValues,matchesProperty,maxBy,minBy,merge,modArgs,' +
-      'modArgsSet,omit,pad,padLeft,padRight,parseInt,partition,pick,pull,pullAll,' +
-      'pullAt,random,range,rearg,reject,remove,repeat,result,sampleSize,set,some,' +
-      'sortBy,sortByOrder,sortedIndexBy,sortedLastIndexBy,sortedUniqBy,startsWith,' +
-      'subtract,sumBy,take,takeRight,takeRightWhile,takeWhile,throttle,times,' +
-      'truncate,union,uniqBy,without,wrap,xor,zip,zipObject').split(','),
+      'lastIndexOf,map,mapKeys,mapValues,matchesProperty,maxBy,mean,minBy,merge,' +
+      'modArgs,modArgsSet,omit,pad,padLeft,padRight,parseInt,partition,pick,pull,' +
+      'pullAll,pullAt,random,range,rearg,reject,remove,repeat,result,sampleSize,' +
+      'set,some,sortBy,sortByOrder,sortedIndexBy,sortedLastIndexBy,sortedUniqBy,' +
+      'startsWith,subtract,sumBy,take,takeRight,takeRightWhile,takeWhile,throttle,' +
+      'times,truncate,union,uniqBy,without,wrap,xor,zip,zipObject').split(','),
     3: (
       'assignWith,clamp,differenceBy,extendWith,getOr,inRange,intersectionBy,' +
       'isEqualWith,isMatchWith,mergeWith,omitBy,pickBy,pullAllBy,reduce,' +
diff --git a/lodash.js b/lodash.js
index 034e6d353..58cf52f6a 100644
--- a/lodash.js
+++ b/lodash.js
@@ -1521,15 +1521,15 @@
      * `isNaN`, `isNative`, `isNil`, `isNull`, `isNumber`, `isObject`, `isObjectLike`,
      * `isPlainObject`, `isRegExp`, `isSafeInteger`, `isString`, `isUndefined`,
      * `isTypedArray`, `join`, `kebabCase`, `last`, `lastIndexOf`, `lowerCase`,
-     * `lowerFirst`, `lt`, `lte`, `max`, `maxBy`, `min`, `minBy`, `noConflict`,
-     * `noop`, `now`, `pad`, `padLeft`, `padRight`, `parseInt`, `pop`, `random`,
-     * `reduce`, `reduceRight`, `repeat`, `result`, `round`, `runInContext`,
-     * `sample`, `shift`, `size`, `snakeCase`, `some`, `sortedIndex`, `sortedIndexBy`,
-     * `sortedLastIndex`, `sortedLastIndexBy`, `startCase`, `startsWith`, `subtract`,
-     * `sum`, sumBy`, `template`, `toLower`, `toInteger`, `toLength`, `toNumber`,
-     * `toSafeInteger`, toString`, `toUpper`, `trim`, `trimLeft`, `trimRight`,
-     * `truncate`, `unescape`, `uniqueId`, `upperCase`, `upperFirst`, `value`,
-     * and `words`
+     * `lowerFirst`, `lt`, `lte`, `max`, `maxBy`, `mean`, `min`, `minBy`,
+     * `noConflict`, `noop`, `now`, `pad`, `padLeft`, `padRight`, `parseInt`,
+     * `pop`, `random`, `reduce`, `reduceRight`, `repeat`, `result`, `round`,
+     * `runInContext`, `sample`, `shift`, `size`, `snakeCase`, `some`, `sortedIndex`,
+     * `sortedIndexBy`, `sortedLastIndex`, `sortedLastIndexBy`, `startCase`,
+     * `startsWith`, `subtract`, `sum`, sumBy`, `template`, `toLower`, `toInteger`,
+     * `toLength`, `toNumber`, `toSafeInteger`, toString`, `toUpper`, `trim`,
+     * `trimLeft`, `trimRight`, `truncate`, `unescape`, `uniqueId`, `upperCase`,
+     * `upperFirst`, `value`, and `words`
      *
      * @name _
      * @constructor
@@ -13335,6 +13335,23 @@
         : undefined;
     }
 
+    /**
+     * Computes the mean value of an `array`.
+     *
+     * @static
+     * @memberOf _
+     * @category Math
+     * @param {Array} array The array to iterate over.
+     * @returns {number} Returns the mean.
+     * @example
+     *
+     * _.mean([4, 2, 8, 6]);
+     * // => 5
+     */
+    function mean(array) {
+      return sum(array) / (array ? array.length : 0);
+    }
+
     /**
      * Gets the minimum value of `array`. If `array` is empty or falsey
      * `undefined` is returned.
@@ -13446,8 +13463,8 @@
      * @returns {number} Returns the sum.
      * @example
      *
-     * _.sum([4, 6]);
-     * // => 10
+     * _.sum([4, 2, 8, 6]);
+     * // => 20
      */
     function sum(array) {
       return (array && array.length)
@@ -13468,17 +13485,14 @@
      * @returns {number} Returns the sum.
      * @example
      *
-     * var objects = [
-     *   { 'n': 4 },
-     *   { 'n': 6 }
-     * ];
+     * var objects = [{ 'n': 4 }, { 'n': 2 }, { 'n': 8 }, { 'n': 6 }];
      *
      * _.sumBy(objects, function(o) { return o.n; });
-     * // => 10
+     * // => 20
      *
      * // using the `_.property` callback shorthand
      * _.sumBy(objects, 'n');
-     * // => 10
+     * // => 20
      */
     function sumBy(array, iteratee) {
       return (array && array.length)
@@ -13747,6 +13761,7 @@
     lodash.lte = lte;
     lodash.max = max;
     lodash.maxBy = maxBy;
+    lodash.mean = mean;
     lodash.min = min;
     lodash.minBy = minBy;
     lodash.noConflict = noConflict;
diff --git a/test/test.js b/test/test.js
index ecf040102..17280376b 100644
--- a/test/test.js
+++ b/test/test.js
@@ -12207,6 +12207,19 @@
 
   /*--------------------------------------------------------------------------*/
 
+  QUnit.module('lodash.mean');
+
+  (function() {
+    QUnit.test('should return the mean of an array of numbers', function(assert) {
+      assert.expect(1);
+
+      var array = [4, 2, 8, 6];
+      assert.strictEqual(_.mean(array), 5);
+    });
+  }());
+
+  /*--------------------------------------------------------------------------*/
+
   QUnit.module('lodash.memoize');
 
   (function() {
@@ -22426,7 +22439,7 @@
     var acceptFalsey = lodashStable.difference(allMethods, rejectFalsey);
 
     QUnit.test('should accept falsey arguments', function(assert) {
-      assert.expect(277);
+      assert.expect(278);
 
       var emptyArrays = lodashStable.map(falsey, lodashStable.constant([]));