Merge 77e5d26 into 71069ef

.editorconfig

@@ -0,0 +1,11 @@
+root = true
+
+[*]
+indent_style = tab
+end_of_line = lf
+charset = utf-8
+trim_trailing_whitespace = true
+insert_final_newline = true
+
+[*.md]
+trim_trailing_whitespace = false

.gitattributes

@@ -0,0 +1 @@
+* text=auto

.jshintignore

@@ -0,0 +1,14 @@
+
+# Directories #
+###############
+build/
+reports/
+dist/
+
+# Node.js #
+###########
+/node_modules/
+
+# Git #
+#######
+.git*

.jshintrc

@@ -0,0 +1,71 @@
+{
+	"bitwise": false,
+	"camelcase": false,
+	"curly": true,
+	"eqeqeq": true,
+	"es3": false,
+	"forin": true,
+	"freeze": true,
+	"immed": true,
+	"indent": 4,
+	"latedef": "nofunc",
+	"newcap": true,
+	"noarg": true,
+	"noempty": false,
+	"nonbsp": true,
+	"nonew": true,
+	"plusplus": false,
+	"quotmark": "single",
+	"undef": true,
+	"unused": true,
+	"strict": true,
+	"maxparams": 10,
+	"maxdepth": 5,
+	"maxstatements": 100,
+	"maxcomplexity": false,
+	"maxlen": 1000,
+	"asi": false,
+	"boss": false,
+	"debug": false,
+	"eqnull": false,
+	"esnext": false,
+	"evil": false,
+	"expr": false,
+	"funcscope": false,
+	"globalstrict": false,
+	"iterator": false,
+	"lastsemic": false,
+	"laxbreak": false,
+	"laxcomma": false,
+	"loopfunc": false,
+	"maxerr": 1000,
+	"moz": false,
+	"multistr": false,
+	"notypeof": false,
+	"proto": false,
+	"scripturl": false,
+	"shadow": false,
+	"sub": true,
+	"supernew": false,
+	"validthis": false,
+	"noyield": false,
+	"browser": true,
+	"browserify": true,
+	"couch": false,
+	"devel": true,
+	"dojo": false,
+	"jasmine": false,
+	"jquery": false,
+	"mocha": true,
+	"mootools": false,
+	"node": true,
+	"nonstandard": false,
+	"prototypejs": false,
+	"qunit": false,
+	"rhino": false,
+	"shelljs": false,
+	"worker": false,
+	"wsh": false,
+	"yui": false,
+	"globals": {}
+}

.npmignore

@@ -13,6 +13,7 @@ examples/
 reports/
 support/
 test/
+benchmark/
 
 # Node.js #
 ###########
@@ -46,4 +47,6 @@ Desktop.ini
 # Utilities #
 #############
 .jshintrc
-.travis.yml
+.jshintignore
+.travis.yml
+.editorconfig

.travis.yml

@@ -1,5 +1,12 @@
 language: node_js
 node_js:
-  - "0.10"
+  - '0.12'
+  - '0.11'
+  - '0.10'
+  - '0.8'
+  - 'iojs'
+before_install:
+  - npm update -g npm
 after_script:
-  - npm run coveralls
+  - npm run coveralls
+

Makefile

@@ -8,29 +8,31 @@ NODE_ENV ?= test
 
 # NOTES #
 
-NOTES ?= 'TODO|FIXME'
+NOTES ?= 'TODO|FIXME|WARNING|HACK|NOTE'
 
 
 # MOCHA #
 
-# Specify the test framework bin locations:
 MOCHA ?= ./node_modules/.bin/mocha
 _MOCHA ?= ./node_modules/.bin/_mocha
-
-# Specify the mocha reporter:
 MOCHA_REPORTER ?= spec
 
 
 # ISTANBUL #
 
-# Istanbul configuration:
 ISTANBUL ?= ./node_modules/.bin/istanbul
 ISTANBUL_OUT ?= ./reports/coverage
 ISTANBUL_REPORT ?= lcov
 ISTANBUL_LCOV_INFO_PATH ?= $(ISTANBUL_OUT)/lcov.info
 ISTANBUL_HTML_REPORT_PATH ?= $(ISTANBUL_OUT)/lcov-report/index.html
 
 
+# JSHINT #
+
+JSHINT ?= ./node_modules/.bin/jshint
+JSHINT_REPORTER ?= ./node_modules/jshint-stylish/stylish.js
+
+
 
 # FILES #
 
@@ -81,7 +83,8 @@ test-istanbul-mocha: node_modules
 	NODE_ENV=$(NODE_ENV) \
 	NODE_PATH=$(NODE_PATH_TEST) \
 	$(ISTANBUL) cover \
-	--dir $(ISTANBUL_OUT) --report $(ISTANBUL_REPORT) \
+		--dir $(ISTANBUL_OUT) \
+		--report $(ISTANBUL_REPORT) \
 	$(_MOCHA) -- \
 		--reporter $(MOCHA_REPORTER) \
 		$(TESTS)
@@ -99,6 +102,18 @@ view-istanbul-report:
 
 
 
+# LINT #
+
+.PHONY: lint lint-jshint
+
+lint: lint-jshint
+
+lint-jshint: node_modules
+	$(JSHINT) \
+		--reporter $(JSHINT_REPORTER) \
+		./
+
+
 # NODE #
 
 # Installing node_modules:
@@ -116,7 +131,6 @@ clean-node:
 
 
 # CLEAN #
-
 .PHONY: clean
 
 clean:

README.md

@@ -2,7 +2,7 @@ Variance
 ===
 [![NPM version][npm-image]][npm-url] [![Build Status][travis-image]][travis-url] [![Coverage Status][coveralls-image]][coveralls-url] [![Dependencies][dependencies-image]][dependencies-url]
 
-> Computes the sample variance over an array of values.
+> Computes the [variance](http://en.wikipedia.org/wiki/Variance) of an array.
 
 
 ## Installation
@@ -16,17 +16,73 @@ For use in the browser, use [browserify](https://github.com/substack/node-browse
 
 ## Usage
 
-To use the module,
-
 ``` javascript
 var variance = require( 'compute-variance' );
 ```
 
+### variance( arr[, opts] )
+
+Computes the [variance](http://en.wikipedia.org/wiki/Variance) of an `array`. For numeric `arrays`,
+
+``` javascript
+var data = [ 2, 4, 5, 3, 4, 3, 1, 5, 6, 9 ];
+
+var s2 = variance( data );
+// returns 5.067
+```
+
+The function accepts two `options`:
+
+*	__accessor__: accessor `function` for accessing `array` values
+*	__bias__: `boolean` indicating whether to compute the population variance (biased sample variance) or the (unbiased) sample variance. Default: `false`; i.e., the unbiased sample variance.
+
+For non-numeric `arrays`, provide an accessor `function` for accessing numeric `array` values
+
+``` javascript
+var data = [
+    {'x':2},
+    {'x':4},
+    {'x':5},
+    {'x':3},
+    {'x':4},
+    {'x':3},
+    {'x':1},
+    {'x':5},
+    {'x':6},
+    {'x':9}
+];
+
+function getValue( d ) {
+    return d.x;
+}
+
+var s2 = variance( data, {
+	'accessor': getValue
+});
+// returns 5.067
+```
+
+By default, the function calculates the *unbiased* sample variance. To calculate the population variance (or a *biased* sample variance), set the `bias` option to `true`.
+
+``` javascript
+var data = [ 2, 4, 5, 3, 4, 3, 1, 5, 6, 9 ];
+
+var value = variance( data, {
+	'bias': true	
+});
+// returns 4.56
+```
+
+__Note__: if provided an empty `array`, the function returns `null`.
+
+
+
 ## Examples
 
 ``` javascript
-var data = new Array( 1000 );
+var variance = require( 'compute-variance' );
 
+var data = new Array( 1000 );
 for ( var i = 0; i < data.length; i++ ) {
 	data[ i ] = Math.random() * 100;
 }
@@ -45,7 +101,7 @@ $ node ./examples/index.js
 
 ### Unit
 
-Unit tests use the [Mocha](http://visionmedia.github.io/mocha) test framework with [Chai](http://chaijs.com) assertions. To run the tests, execute the following command in the top-level application directory:
+Unit tests use the [Mocha](http://mochajs.org) test framework with [Chai](http://chaijs.com) assertions. To run the tests, execute the following command in the top-level application directory:
 
 ``` bash
 $ make test
@@ -65,16 +121,14 @@ $ make test-cov
 Istanbul creates a `./reports/coverage` directory. To access an HTML version of the report,
 
 ``` bash
-$ open reports/coverage/lcov-report/index.html
+$ make view-cov
 ```
 
-
+---
 ## License
 
-[MIT license](http://opensource.org/licenses/MIT). 
-
+[MIT license](http://opensource.org/licenses/MIT).
 
----
 ## Copyright
 
 Copyright &copy; 2014. Athan Reines.
@@ -96,4 +150,4 @@ Copyright &copy; 2014. Athan Reines.
 [dev-dependencies-url]: https://david-dm.org/dev/compute-io/variance
 
 [github-issues-image]: http://img.shields.io/github/issues/compute-io/variance.svg
-[github-issues-url]: https://github.com/compute-io/variance/issues
+[github-issues-url]: https://github.com/compute-io/variance/issues

TODO.md

@@ -1,4 +1,3 @@
 TODO
 ====
 
-

examples/index.js

@@ -1,9 +1,9 @@
+'use strict';
+
 var variance = require( './../lib' );
 
 var data = new Array( 1000 );
-
 for ( var i = 0; i < data.length; i++ ) {
 	data[ i ] = Math.random() * 100;
 }
-
-console.log( variance( data ) );
+console.log( variance( data ) );