177 lines
3.4 KiB
Markdown
177 lines
3.4 KiB
Markdown
<!--
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@license Apache-2.0
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Copyright (c) 2018 The Stdlib Authors.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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-->
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# Shuffle
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> Shuffle elements of an array-like object.
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<section class="intro">
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</section>
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<!-- /.intro -->
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<section class="usage">
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## Usage
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```javascript
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var shuffle = require( '@stdlib/random/shuffle' );
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```
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#### shuffle( arr\[, options] )
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Shuffles elements of an array-like object.
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```javascript
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var arr = [ 1, 2, 3 ];
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var out = shuffle( arr );
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// e.g., returns [ 3, 1, 2 ]
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```
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The function accepts the following `options`:
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- **copy**: `string` indicating whether to return a copy (`deep`,`shallow` or `none`). Default: `shallow`.
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By default, the function returns a shallow copy. To mutate the input `array` (e.g., when input values can be discarded or when optimizing memory usage), set `copy` to `none`.
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```javascript
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var arr = [ 1, 2, 3 ];
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var out = shuffle( arr, {
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'copy': 'none'
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});
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var bool = ( arr === out );
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// returns true
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```
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To return a deep copy, set the `copy` option to `deep`.
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```javascript
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var obj = {
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'beep': 'boop'
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};
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var arr = [ [ obj ], [ obj ], [ obj ] ];
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// Deep copy:
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var out = shuffle( arr, {
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'copy': 'deep'
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});
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var bool = ( arr === out );
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// returns false
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bool = ( arr[2] === out[2] );
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// returns false
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// Shallow copy:
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out = shuffle( arr, {
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'copy': 'shallow'
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});
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bool = ( arr === out );
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// returns false
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bool = ( arr[2] === out[2] );
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// returns true
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```
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#### shuffle.factory( \[options] )
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Returns a `function` to shuffle elements of `array`-like objects.
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```javascript
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var myshuffle = shuffle.factory();
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```
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The function accepts the following `options`:
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- **copy**: `string` specifying the default copy option (`deep`,`shallow` or `none`). Default: `shallow`.
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- **seed**: pseudorandom number generator seed.
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To seed the underlying pseudorandom number generator, set the `seed` option.
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```javascript
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var myshuffle = shuffle.factory({
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'seed': 239
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});
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var out = myshuffle( [ 0, 1, 2, 3, 4 ] );
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// e.g., returns [ 3, 4, 1, 0, 2 ]
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```
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By default, the returned functions create shallow copies when shuffling. To override the default `copy` strategy, set the `copy` option.
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```javascript
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var myshuffle = shuffle.factory({
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'copy': 'none',
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'seed': 867
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});
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// Created shuffle function mutates input array by default:
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var arr = [ 1, 2, 3, 4, 5, 6 ];
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var out = myshuffle( arr );
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var bool = ( arr === out );
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// returns true
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// Default option can be overridden:
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arr = [ 1, 2, 3, 4 ];
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out = myshuffle( arr, {
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'copy': 'shallow'
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});
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bool = ( arr === out );
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// returns false
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```
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</section>
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<!-- /.usage -->
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<section class="examples">
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## Examples
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<!-- eslint no-undef: "error" -->
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```javascript
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var shuffle = require( '@stdlib/random/shuffle' );
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var result;
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var data;
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var i;
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data = new Array( 20 );
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for ( i = 0; i < data.length; i++ ) {
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data[ i ] = i;
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}
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for ( i = 0; i < 10; i++ ) {
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result = shuffle( data );
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console.log( result );
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}
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```
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</section>
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<!-- /.examples -->
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<section class="links">
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</section>
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<!-- /.links -->
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