npm package: @stdlib/array-base-map4d
Description: Apply a function to elements in a four-dimensional nested input array and assign results to elements in a new four-dimensional nested output array.
Author: The Stdlib Authors
Latest version: 0.2.3

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# map4d

[![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url] <!-- [![dependencies][dependencies-image]][dependencies-url] -->

> Apply a function to elements in a four-dimensional nested input array and assign results to elements in a new four-dimensional nested output array.

<section class="intro">

</section>

<!-- /.intro -->

<section class="installation">

## Installation

```bash
npm install @stdlib/array-base-map4d
```

</section>

<section class="usage">

## Usage

```javascript
var map4d = require( '@stdlib/array-base-map4d' );
```

#### map4d( x, shape, fcn\[, thisArg] )

Applies a function to elements in a four-dimensional nested input array and assigns results to elements in a new four-dimensional nested output array.

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

var x = [ [ [ [ -1.0, -2.0 ], [ -3.0, -4.0 ] ] ] ];
var shape = [ 1, 1, 2, 2 ];

var y = map4d( x, shape, naryFunction( abs, 1 ) );
// returns [ [ [ [ 1.0, 2.0 ], [ 3.0, 4.0 ] ] ] ]
```

The function accepts the following arguments:

-   **x**: input nested array.
-   **shape**: array shape.
-   **fcn**: function to apply.
-   **thisArg**: applied function execution context (_optional_).

To set the applied function's execution context, provide a `thisArg`.

<!-- eslint-disable no-invalid-this -->

```javascript
function fcn( x ) {
    this.count += 1;
    return x;
}

var x = [ [ [ [ 1.0, 2.0 ], [ 3.0, 4.0 ] ] ] ];
var shape = [ 1, 1, 2, 2 ];

var ctx = {
    'count': 0
};

var y = map4d( x, shape, fcn, ctx );
// returns [ [ [ [ 1.0, 2.0 ], [ 3.0, 4.0 ] ] ] ]

var v = ctx.count;
// returns 4
```

#### map4d.assign( x, y, shape, fcn\[, thisArg] )

Applies a function to elements in a four-dimensional nested input array and assigns results to elements in a four-dimensional nested output array.

```javascript
var naryFunction = require( '@stdlib/utils-nary-function' );
var zeros4d = require( '@stdlib/array-base-zeros4d' );
var abs = require( '@stdlib/math-base-special-abs' );

var x = [ [ [ [ -1.0, -2.0 ], [ -3.0, -4.0 ] ] ] ];
var shape = [ 1, 1, 2, 2 ];

var y = zeros4d( shape );

var out = map4d.assign( x, y, shape, naryFunction( abs, 1 ) );
// returns [ [ [ [ 1.0, 2.0 ], [ 3.0, 4.0 ] ] ] ]

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

The function accepts the following arguments:

-   **x**: input nested array.
-   **y**: output nested array.
-   **shape**: array shape.
-   **fcn**: function to apply.
-   **thisArg**: applied function execution context (_optional_).

The function assumes that the input and output arrays have the same shape.

</section>

<!-- /.usage -->

<section class="notes">

</section>

<!-- /.notes -->

<section class="examples">

## Examples

<!-- eslint no-undef: "error" -->

```javascript
var discreteUniform = require( '@stdlib/random-base-discrete-uniform' ).factory;
var filled4dBy = require( '@stdlib/array-base-filled4d-by' );
var naryFunction = require( '@stdlib/utils-nary-function' );
var abs = require( '@stdlib/math-base-special-abs' );
var map4d = require( '@stdlib/array-base-map4d' );

var shape = [ 1, 3, 3, 3 ];

var x = filled4dBy( shape, discreteUniform( -100, 100 ) );
console.log( x );

var y = map4d( x, shape, naryFunction( abs, 1 ) );
console.log( y );
```

</section>

<!-- /.examples -->

<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. -->

<section class="related">

</section>

<!-- /.related -->

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<section class="main-repo" >

* * *

## Notice

This package is part of [stdlib][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][stdlib], see the main project [repository][stdlib].

#### Community

[![Chat][chat-image]][chat-url]

---

## License

See [LICENSE][stdlib-license].


## Copyright

Copyright &copy; 2016-2026. The Stdlib [Authors][stdlib-authors].

</section>

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