npm package: @stdlib/array-base-mskunary4d
Description: Apply a unary callback to elements in a four-dimensional nested input array according to elements in a four-dimensional nested mask array and assign results to elements in a four-dimensional nested output array.
Author: The Stdlib Authors
Latest version: 0.1.1

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# mskunary4d

[![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 unary callback to elements in a four-dimensional nested input array according to elements in a four-dimensional nested mask array and assign results to elements in a four-dimensional nested output array.

<section class="intro">

</section>

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<section class="installation">

## Installation

```bash
npm install @stdlib/array-base-mskunary4d
```

</section>

<section class="usage">

## Usage

```javascript
var mskunary4d = require( '@stdlib/array-base-mskunary4d' );
```

#### mskunary4d( arrays, shape, fcn )

Applies a unary callback to elements in a four-dimensional nested input array according to elements in a four-dimensional nested mask array and assigns results to elements in a four-dimensional nested output array.

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

var x = [ [ [ [ -1.0, -2.0 ], [ -3.0, -4.0 ] ] ] ];
var mask = [ [ [ [ 0, 1 ], [ 0, 0 ] ] ] ];

var shape = [ 1, 1, 2, 2 ];

// Compute the absolute values in-place:
mskunary4d( [ x, mask, x ], shape, abs );
// x => [ [ [ [ 1.0, -2.0 ], [ 3.0, 4.0 ] ] ] ]
```

The function accepts the following arguments:

-   **arrays**: array-like object containing one input nested array, an input nested mask array, and one output nested array.
-   **shape**: array shape.
-   **fcn**: unary function to apply.

</section>

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<section class="notes">

## Notes

-   The function assumes that the input and output arrays have the same shape.
-   An element in an input array is "masked" if the corresponding element in the mask array is non-zero.

</section>

<!-- /.notes -->

<section class="examples">

## Examples

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

```javascript
var discreteUniform = require( '@stdlib/random-base-discrete-uniform' ).factory;
var bernoulli = require( '@stdlib/random-base-bernoulli' ).factory;
var filled4dBy = require( '@stdlib/array-base-filled4d-by' );
var zeros4d = require( '@stdlib/array-base-zeros4d' );
var abs = require( '@stdlib/math-base-special-abs' );
var mskunary4d = require( '@stdlib/array-base-mskunary4d' );

var shape = [ 2, 3, 3, 3 ];

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

var mask = filled4dBy( shape, bernoulli( 0.5 ) );
console.log( mask );

var y = zeros4d( shape );
console.log( y );

mskunary4d( [ x, mask, y ], shape, abs );
console.log( y );
```

</section>

<!-- /.examples -->

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<section class="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

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---

## License

See [LICENSE][stdlib-license].


## Copyright

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

</section>

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