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    @stdlib/utils-flatten-array
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    0.0.6 • Public • Published

    Flatten Array

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    Flatten an array.

    Installation

    npm install @stdlib/utils-flatten-array

    Usage

    var flattenArray = require( '@stdlib/utils-flatten-array' );

    flattenArray( arr[, options] )

    Flattens an array.

    var arr = [ 1, [2, [3, [4, [ 5 ], 6], 7], 8], 9 ];
    
    var out = flattenArray( arr );
    // returns [ 1, 2, 3, 4, 5, 6, 7, 8, 9 ]

    The function accepts the following options:

    • depth: maximum depth to flatten.
    • copy: boolean indicating whether to deep copy array elements. Default: false.

    To flatten to a specified depth, set the depth option.

    var arr = [ 1, [2, [3, [4, [ 5 ], 6], 7], 8], 9 ];
    
    var out = flattenArray( arr, {
        'depth': 2
    });
    // returns [ 1, 2, 3, [4, [5], 6], 7, 8, 9 ]
    
    var bool = ( arr[1][1][1] === out[3] );
    // returns true

    To deep copy array elements, set the copy option to true.

    var arr = [ 1, [2, [3, [4, [ 5 ], 6], 7], 8], 9 ];
    
    var out = flattenArray( arr, {
        'depth': 2,
        'copy': true
    });
    // returns [ 1, 2, 3, [4, [5], 6], 7, 8, 9 ]
    
    var bool = ( arr[1][1][1] === out[3] );
    // returns false

    flattenArray.factory( dims[, options] )

    Returns a function optimized for flattening arrays having specified dimensions.

    var flatten = flattenArray.factory( [ 3, 3 ] );
    
    var arr = [
        [ 1, 2, 3 ],
        [ 4, 5, 6 ],
        [ 7, 8, 9 ]
    ];
    
    var out = flatten( arr );
    // returns [ 1, 2, 3, 4, 5, 6, 7, 8, 9 ]
    
    arr = [
        [ 11, 12, 13 ],
        [ 14, 15, 16 ],
        [ 17, 18, 19 ]
    ];
    
    out = flatten( arr );
    // returns [ 11, 12, 13, 14, 15, 16, 17, 18, 19 ]

    The function accepts the following options:

    • copy: boolean indicating whether to deep copy array elements. Default: false.

    To deep copy array elements, set the copy option to true.

    var flatten = flattenArray.factory( [ 3, 3 ], {
        'copy': true
    });
    
    var arr = [
        [ 1, 2, 3 ],
        [ 4, { 'x': 5 }, 6 ],
        [ 7, 8, 9 ]
    ];
    
    var out = flatten( arr );
    // returns [ 1, 2, 3, 4, {'x':5}, 6, 7, 8, 9 ]
    
    var bool = ( arr[1][1] === out[4] );
    // returns false

    Notes

    • A flatten function returned by the factory method does not validate that input arrays actually have the specified dimensions.

    Examples

    var flattenArray = require( '@stdlib/utils-flatten-array' );
    
    var xStride;
    var yStride;
    var zStride;
    var bool;
    var tmp1;
    var tmp2;
    var arr;
    var val;
    var out;
    var N;
    var M;
    var L;
    var i;
    var j;
    var k;
    
    N = 1000;
    M = 100;
    L = 10;
    
    // Create an NxMxL (3D) array...
    arr = new Array( N );
    for ( i = 0; i < N; i++ ) {
        tmp1 = new Array( M );
        for ( j = 0; j < M; j++ ) {
            tmp2 = new Array( L );
            for ( k = 0; k < L; k++ ) {
                tmp2[ k ] = (M*L*i) + (j*L) + k + 1;
            }
            tmp1[ j ] = tmp2;
        }
        arr[ i ] = tmp1;
    }
    // Create a flattened (strided) array:
    out = flattenArray( arr );
    
    // To access the arr[4][20][2] element...
    xStride = M * L;
    yStride = L;
    zStride = 1;
    val = out[ (4*xStride) + (20*yStride) + (2*zStride) ];
    // returns 4203
    
    bool = ( arr[4][20][2] === val );
    // returns true

    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.

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    License

    See LICENSE.

    Copyright

    Copyright © 2016-2021. The Stdlib Authors.

    Install

    npm i @stdlib/utils-flatten-array

    Homepage

    stdlib.io

    DownloadsWeekly Downloads

    64

    Version

    0.0.6

    License

    Apache-2.0

    Unpacked Size

    58.4 kB

    Total Files

    17

    Last publish

    Collaborators

    • stdlib-bot
    • kgryte
    • planeshifter
    • rreusser