70 lines
1.8 KiB
Markdown
70 lines
1.8 KiB
Markdown
knuth-shuffle
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=============
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The Fisher-Yates (aka Knuth) shuffle for Browser and Node.js
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* [Mike Bostock's Fisher–Yates Shuffle Visualization](http://bost.ocks.org/mike/shuffle/)
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* [How to randomize/shuffle a JavaScript array](http://stackoverflow.com/questions/2450954/how-to-randomize-shuffle-a-javascript-array)
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* [Fisher-Yates Shuffle on Wikipedia](http://en.wikipedia.org/wiki/Fisher%E2%80%93Yates_shuffle)
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* [Doing the Microsoft Shuffle: Algorithm Fail in Browser Ballot](http://www.robweir.com/blog/2010/02/microsoft-random-browser-ballot.html)
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* [knuth-shuffle on NPM](https://npmjs.org/package/knuth-shuffle)
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'nuf said.
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The Fisher-Yates (Knuth) Shuffle
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===
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As Microsoft learned the hard way (see article below), `function random() { return 0.5 - Math.random() }` turns out to be no-so-random at all.
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The fisher-yates shuffle is an algorithm so simple that even
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[IEEE floating point math](http://blogs.adobe.com/bparadie/2011/11/22/0-2-0-1-0-30000000000000004/)
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can't screw it up!
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I put this on npm as `knuth-shuffle` because `fisher-yates-shuffle`
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was just too long of a name and shuffle was already taken.
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Browser Example
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===
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```html
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<script src="https://raw.github.com/coolaj86/knuth-shuffle/master/index.js"></script>
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```
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```javascript
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(function () {
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'use strict';
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var a = [2,11,37,42]
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, b
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;
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// The shuffle modifies the original array
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// calling a.slice(0) creates a copy, which is assigned to b
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b = window.knuthShuffle(a.slice(0));
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console.log(b);
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}());
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```
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Node Example
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===
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```bash
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npm install -S knuth-shuffle
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```
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```javascript
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(function () {
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'use strict';
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var shuffle = require('knuth-shuffle').knuthShuffle
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, a = [2,11,37,42]
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, b
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;
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// The shuffle modifies the original array
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// calling a.slice(0) creates a copy, which is assigned to b
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b = shuffle(a.slice(0));
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console.log(b);
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}());
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```
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