immutable-shuffle

Fisher-Yates shuffle for immutable.js

Immutable.js is an awesome, but does not provide a way to shuffle lists out of the box.

This module implements Fisher-Yates Shuffle for immutable.js. Some say it is the only way to shuffle an array in JavaScript.

Table of Contents

• Install
• Usage
• Performance
• Contribute
• License

Install

npm install immutable-shuffle

Usage

import shuffle from 'immutable-shuffle';

const list = Immutable.fromJS([1, 2, 3, 4, 5]);
const shuffled = shuffle(list);

Performance

A naive shuffle could be implemented as follows:

const shuffled = list.sortBy(Math.random);

Compared to a fisher-yates shuffle this implementation is much slower.
On a Macbook Air 2013:

array of 100 elements
naive: 2.503ms
fisher-yates: 0.568ms

array of 1000 elements
naive: 10.218ms
fisher-yates: 4.500ms

array of 10000 elements
naive: 30.075ms
fisher-yates: 13.920ms

array of 100000 elements
naive: 357.804ms
fisher-yates: 84.567ms

array of 1000000 elements
naive: 2877.592ms
fisher-yates: 833.101ms

Contribute

PRs are very welcome.

Small note: If editing the README, please conform to the standard-readme specification.

License

MIT © Tobias Kloht