map4d

Apply a function to each nested element in a four-dimensional nested array and assign the result to a nested element in a new four-dimensional nested array.

Installation

npm install @stdlib/utils-map4d

Usage

var map4d = require( '@stdlib/utils-map4d' );

map4d( arr, fcn[, thisArg] )

Applies a function to each nested element in a four-dimensional nested array and assigns the result to a nested element in a new four-dimensional nested array.

var naryFunction = require( '@stdlib/utils-nary-function' );
var abs = require( '@stdlib/math-base-special-abs' );

var arr = [
    [ [ [ -1, -2, -3 ] ] ],
    [ [ [ -4, -5, -6 ] ] ]
];

var out = map4d( arr, naryFunction( abs, 1 ) );
// returns [ [ [ [ 1, 2, 3 ] ] ], [ [ [ 4, 5, 6 ] ] ] ]

The applied function is provided the following arguments:

• value: array element.
• indices: current array element indices.
• arr: input array.

To set the this context when invoking the input function, provide a thisArg.

var abs = require( '@stdlib/math-base-special-abs' );

function fcn( v ) {
    this.count += 1;
    return abs( v );
}

var arr = [
    [ [ [ -1, -2, -3 ] ] ],
    [ [ [ -4, -5, -6 ] ] ]
];

var ctx = {
    'count': 0
};

var out = map4d( arr, fcn, ctx );
// returns [ [ [ [ 1, 2, 3 ] ] ], [ [ [ 4, 5, 6 ] ] ] ]

var cnt = ctx.count;
// returns 6

Examples

var filledarrayBy = require( '@stdlib/array-filled-by' );
var discreteUniform = require( '@stdlib/random-base-discrete-uniform' ).factory;
var naryFunction = require( '@stdlib/utils-nary-function' );
var abs2 = require( '@stdlib/math-base-special-abs2' );
var map4d = require( '@stdlib/utils-map4d' );

function fill( n ) {
    if ( n > 0 ) {
        return array;
    }
    return values;

    function array() {
        return filledarrayBy( 2, 'generic', fill( n-1 ) );
    }

    function values( i ) {
        var rand = discreteUniform( -10*(i+1), 10*(i+1) );
        return filledarrayBy( 10, 'generic', rand );
    }
}

// Create a four-dimensional nested array:
var x = filledarrayBy( 2, 'generic', fill( 2 ) );

// Create an explicit unary function:
var f = naryFunction( abs2, 1 );

// Compute the element-wise squared absolute value...
var y = map4d( x, f );

console.log( 'x:' );
console.log( JSON.stringify( x, null, '  ' ) );

console.log( 'y:' );
console.log( JSON.stringify( y, null, '  ' ) );

See Also

• @stdlib/utils-map: apply a function to each element in an array and assign the result to an element in an output array.
• @stdlib/utils-map2d: apply a function to each nested element in an array of arrays and assign the result to a nested element in a new array of arrays.
• @stdlib/utils-map3d: apply a function to each nested element in a three-dimensional nested array and assign the result to a nested element in a new three-dimensional nested array.
• @stdlib/utils-map5d: apply a function to each nested element in a five-dimensional nested array and assign the result to a nested element in a new five-dimensional nested array.

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.

Community

License

See LICENSE.

Copyright

Copyright © 2016-2024. The Stdlib Authors.