@stdlib/random-shuffle NPM

Shuffle

Shuffle elements of an array-like object.

Installation

npm install @stdlib/random-shuffle

Usage

var shuffle = require( '@stdlib/random-shuffle' );

shuffle( arr[, options] )

Shuffles elements of an array-like object.

var arr = [ 1, 2, 3 ];
var out = shuffle( arr );
// e.g., returns [ 3, 1, 2 ]

The function accepts the following options:

copy: string indicating whether to return a copy (deep,shallow or none). Default: shallow.

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.

var arr = [ 1, 2, 3 ];
var out = shuffle( arr, {
    'copy': 'none'
});
var bool = ( arr === out );
// returns true

To return a deep copy, set the copy option to deep.

var obj = {
    'beep': 'boop'
};
var arr = [ [ obj ], [ obj ], [ obj ] ];

// Deep copy:
var out = shuffle( arr, {
    'copy': 'deep'
});
var bool = ( arr === out );
// returns false

bool = ( arr[2] === out[2] );
// returns false

// Shallow copy:
out = shuffle( arr, {
    'copy': 'shallow'
});
bool = ( arr === out );
// returns false

bool = ( arr[2] === out[2] );
// returns true

shuffle.factory( [options] )

Returns a function to shuffle elements of array-like objects.

var myshuffle = shuffle.factory();

The function accepts the following options:

copy: string specifying the default copy option (deep,shallow or none). Default: shallow.
seed: pseudorandom number generator seed.

To seed the underlying pseudorandom number generator, set the seed option.

var myshuffle = shuffle.factory({
    'seed': 239
});

var out = myshuffle( [ 0, 1, 2, 3, 4 ] );
// e.g., returns [ 3, 4, 1, 0, 2 ]

By default, the returned functions create shallow copies when shuffling. To override the default copy strategy, set the copy option.

var myshuffle = shuffle.factory({
    'copy': 'none',
    'seed': 867
});

// Created shuffle function mutates input array by default:
var arr = [ 1, 2, 3, 4, 5, 6 ];
var out = myshuffle( arr );
var bool = ( arr === out );
// returns true

// Default option can be overridden:
arr = [ 1, 2, 3, 4 ];
out = myshuffle( arr, {
    'copy': 'shallow'
});
bool = ( arr === out );
// returns false

Examples

var shuffle = require( '@stdlib/random-shuffle' );

var result;
var data;
var i;

data = new Array( 20 );
for ( i = 0; i < data.length; i++ ) {
    data[ i ] = i;
}

for ( i = 0; i < 10; i++ ) {
    result = shuffle( data );
    console.log( result );
}

Notice

This package is part of stdlib, a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.

For more information on the project, filing bug reports and feature requests, and guidance on how to develop stdlib, see the main project repository.