From efa288c00a673ff0205489a72b13d40d7f5b96ae Mon Sep 17 00:00:00 2001
From: davidepastore <pasdavide@gmail.com>
Date: Thu, 29 Jan 2015 16:01:29 +0100
Subject: [PATCH] Add mean filter.

---
 README.md                     |  9 ++++++++
 src/_filter/math/mean.js      | 40 +++++++++++++++++++++++++++++++++++
 src/filters.js                |  1 +
 test/spec/filter/math/mean.js | 28 ++++++++++++++++++++++++
 4 files changed, 78 insertions(+)
 create mode 100644 src/_filter/math/mean.js
 create mode 100644 test/spec/filter/math/mean.js

diff --git a/README.md b/README.md
index 3d66703..37e419f 100644
--- a/README.md
+++ b/README.md
@@ -68,6 +68,7 @@
   - [shortFmt](#shortfmt)
   - [byteFmt](#bytefmt)
   - [kbFmt](#kbfmt)
+  - [mean](#mean)
 - [Boolean](#boolean)
   - [isNull](#isnull)
   - [isDefined](#isdefined)
@@ -1190,6 +1191,14 @@ Converts kilobytes into formatted display<br/>
 1 MB
 1.00126 GB
 
+```
+###mean
+Calculates the mean value from all values within an array<br/>
+**Usage:** ```array | mean```
+```html
+{{ [12,7,5] | mean }}
+<!--result
+8
 ```
 #Boolean
 >Used for boolean expression in chaining filters
diff --git a/src/_filter/math/mean.js b/src/_filter/math/mean.js
new file mode 100644
index 0000000..87e841b
--- /dev/null
+++ b/src/_filter/math/mean.js
@@ -0,0 +1,40 @@
+/**
+ * @ngdoc filter
+ * @name mean
+ * @kind function
+ *
+ * @description
+ * Math.mean will get an array and return the mean value. if an expression
+ * is provided, will return mean value by expression.
+ */
+
+angular.module('a8m.math.mean', ['a8m.math', 'a8m.math.sum'])
+
+  .filter('mean', ['$math', 'sumFilter', function ($math, sumFilter) {
+    return function (input) {
+
+	  if(!isArray(input) || !isNumericArray(input)){
+	    return input;
+	  }
+	  
+      return sumFilter(input) / input.length;
+    };
+	
+	/**
+	 * Check if the given array is numeric.
+	 * @private
+	 * @param array An array given by the input.
+	 * @returns {boolean}
+	 */
+	function isNumericArray(array){
+		var result = true;
+		forEach(array, function(element){
+			if(!isNumber(element)){
+				result = false;
+				return;
+			}
+		});
+		return result;
+	}
+
+  }]);
\ No newline at end of file
diff --git a/src/filters.js b/src/filters.js
index 6174e30..a89372d 100644
--- a/src/filters.js
+++ b/src/filters.js
@@ -63,6 +63,7 @@ angular.module('angular.filter', [
   'a8m.math.byteFmt',
   'a8m.math.kbFmt',
   'a8m.math.shortFmt',
+  'a8m.math.mean',
 
   'a8m.angular',
   'a8m.conditions',
diff --git a/test/spec/filter/math/mean.js b/test/spec/filter/math/mean.js
new file mode 100644
index 0000000..c1c9f90
--- /dev/null
+++ b/test/spec/filter/math/mean.js
@@ -0,0 +1,28 @@
+'use strict';
+
+describe('meanFilter', function () {
+
+  var filter;
+
+  beforeEach(module('a8m.math.mean'));
+
+  beforeEach(inject(function ($filter) {
+    filter = $filter('mean');
+  }));
+
+  it('should return the mean of all members in array', function() {
+    expect(filter([1,2,3,4,5,6])).toEqual(3.5);
+    expect(filter([0,0,0,0,0,3])).toEqual(0.5);
+  });
+
+  it('should return an object if the members type != number', function() {
+    expect(typeof filter([{}, 'string', 'foo'])).toEqual('object')
+  });
+
+  it('should return the input as-is if is not an array', function() {
+    expect(filter('string')).toEqual('string');
+    expect(filter(1)).toEqual(1);
+    expect(filter(!1)).toBeFalsy();
+  })
+
+});