npm package: @stdlib/array-base-mskfilter
Description: Apply a mask to a provided input array.
Author: The Stdlib Authors
Latest version: 0.3.1

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# mskfilter

[![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 mask to a provided input array.

<section class="installation">

## Installation

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

</section>

<section class="usage">

## Usage

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

#### mskfilter( x, mask )

Returns a new array by applying a mask to a provided input array.

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

var y = mskfilter( x, [ 0, 1, 0, 1 ] );
// returns [ 2, 4 ]
```

The function supports the following parameters:

-   **x**: input array.
-   **mask**: mask array.

The function **always** returns a new "generic" array.

#### mskfilter.assign( x, mask, out, stride, offset )

Applies a mask to a provided input array and assigns unmasked values to elements in a provided output array.

```javascript
var x = [ 1, 2, 3, 4 ];
var mask = [ 0, 1, 0, 1 ];

var out = [ 0, 0, 0, 0 ];

var arr = mskfilter.assign( x, mask, out, -2, out.length-1 );
// returns [ 0, 4, 0, 2 ]

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

The function supports the following parameters:

-   **x**: input array.
-   **mask**: mask array.
-   **out**: output array.
-   **stride**: output array stride.
-   **offset**: output array offset.

</section>

<!-- /.usage -->

<section class="notes">

## Notes

-   If a `mask` array element is truthy, the corresponding element in `x` is **included** in the output array; otherwise, the corresponding element in `x` is "masked" and thus **excluded** from the output array.

</section>

<!-- /.notes -->

<section class="examples">

## Examples

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

```javascript
var zeroTo = require( '@stdlib/array-base-zero-to' );
var bernoulli = require( '@stdlib/random-array-bernoulli' );
var mskfilter = require( '@stdlib/array-base-mskfilter' );

// Generate a linearly spaced array:
var x = zeroTo( 20 );
console.log( x );

// Generate a random mask:
var mask = bernoulli( x.length, 0.5, {
    'dtype': 'generic'
});
console.log( mask );

// Filter an array using the mask:
var y = mskfilter( x, mask );
console.log( y );
```

</section>

<!-- /.examples -->

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<section class="related">

</section>

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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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[stdlib]: https://github.com/stdlib-js/stdlib

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[umd]: https://github.com/umdjs/umd
[es-module]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Modules

[deno-url]: https://github.com/stdlib-js/array-base-mskfilter/tree/deno
[deno-readme]: https://github.com/stdlib-js/array-base-mskfilter/blob/deno/README.md
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[branches-url]: https://github.com/stdlib-js/array-base-mskfilter/blob/main/branches.md

[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/array-base-mskfilter/main/LICENSE

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