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flatten2dBy

Flatten a two-dimensional nested array according to a callback function.

Usage

import flatten2dBy from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-base-flatten2d-by@deno/mod.js';

You can also import the following named exports from the package:

import { assign } from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-base-flatten2d-by@deno/mod.js';

flatten2dBy( x, shape, colexicographic, clbk[, thisArg] )

Flattens a two-dimensional nested array according to a callback function.

function scale( v ) {
    return v * 2;
}

var x = [ [ 1, 2 ], [ 3, 4 ] ];

var out = flatten2dBy( x, [ 2, 2 ], false, scale );
// returns [ 2, 4, 6, 8 ]

To flatten in colexicographic order, provide a third argument equal to true.

function scale( v ) {
    return v * 2;
}

var x = [ [ 1, 2 ], [ 3, 4 ] ];

var out = flatten2dBy( x, [ 2, 2 ], true, scale );
// returns [ 2, 6, 4, 8 ]

To set the callback execution context, provide a thisArg argument.

function scale( v ) {
    this.count += 1;
    return v * 2;
}

var x = [ [ 1, 2 ], [ 3, 4 ] ];
var ctx = {
    'count': 0
};

var out = flatten2dBy( x, [ 2, 2 ], false, scale, ctx );
// returns [ 2, 4, 6, 8 ]

var count = ctx.count;
// returns 4

flatten2dBy.assign( x, shape, colexicographic, out, stride, offset, clbk[, thisArg] )

Flattens a two-dimensional nested array according to a callback function and assigns elements to a provided output array.

import Float64Array from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-float64@deno/mod.js';

function scale( v ) {
    return v * 2;
}

var x = [ [ 1, 2 ], [ 3, 4 ] ];
var out = new Float64Array( 4 );

var y = flatten2dBy.assign( x, [ 2, 2 ], false, out, 1, 0, scale );
// returns <Float64Array>[ 2, 4, 6, 8 ]

var bool = ( y === out );
// returns true

y = flatten2dBy.assign( x, [ 2, 2 ], true, out, 1, 0, scale );
// returns <Float64Array>[ 2, 6, 4, 8 ]

Notes

• A callback function is provided the following arguments:

  • value: nested array element.
  • indices: element indices (in lexicographic order).
  • arr: the input array.

• Both functions assume that all nested arrays have the same length (i.e., the input array is not a ragged array).

Examples

import naryFunction from 'https://cdn.jsdelivr.net/gh/stdlib-js/utils-nary-function@deno/mod.js';
import abs from 'https://cdn.jsdelivr.net/gh/stdlib-js/math-base-special-abs@deno/mod.js';
import flatten2dBy from 'https://cdn.jsdelivr.net/gh/stdlib-js/array-base-flatten2d-by@deno/mod.js';

var fcn = naryFunction( abs, 1 );

var x = [
    [ -1, -2, -3, -4 ],
    [ -5, -6, -7, -8 ],
    [ -9, -10, -11, -12 ],
    [ -13, -14, -15, -16 ]
];

var out = flatten2dBy( x, [ 0, 0 ], false, fcn );
// returns []

out = flatten2dBy( x, [ 0, 0 ], true, fcn );
// returns []

out = flatten2dBy( x, [ 1, 1 ], false, fcn );
// returns [ 1 ]

out = flatten2dBy( x, [ 1, 1 ], true, fcn );
// returns [ 1 ]

out = flatten2dBy( x, [ 2, 2 ], false, fcn );
// returns [ 1, 2, 5, 6 ]

out = flatten2dBy( x, [ 2, 2 ], true, fcn );
// returns [ 1, 5, 2, 6 ]

out = flatten2dBy( x, [ 3, 3 ], false, fcn );
// returns [ 1, 2, 3, 5, 6, 7, 9, 10, 11 ]

out = flatten2dBy( x, [ 3, 3 ], true, fcn );
// returns [ 1, 5, 9, 2, 6, 10, 3, 7, 11 ]

out = flatten2dBy( x, [ 4, 4 ], false, fcn );
// returns [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 ]

out = flatten2dBy( x, [ 4, 4 ], true, fcn );
// returns [ 1, 5, 9, 13, 2, 6, 10, 14, 3, 7, 11, 15, 4, 8, 12, 16 ]

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See Also

• @stdlib/array-base/flatten2d: flatten a two-dimensional nested array.

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Notice

This package is part of stdlib, a standard library 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.

Community

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License

See LICENSE.

Copyright

Copyright © 2016-2024. The Stdlib Authors.