npm package: @stdlib/array-base-take-map
Description: Take elements from an array and return a new array after applying a mapping function.
Author: The Stdlib Authors
Latest version: 0.1.2

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# takeMap

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

> Take elements from an array and return a new array after applying a mapping function.

<section class="installation">

## Installation

```bash
npm install @stdlib/array-base-take-map
```

</section>

<section class="usage">

## Usage

```javascript
var takeMap = require( '@stdlib/array-base-take-map' );
```

### takeMap( x, indices, mode, clbk )

Takes elements from an array and returns a new array after applying a mapping function.

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

function customMapping( value ) {
    return value * 2;
}

var y = takeMap( x, [ 1, 3 ], 'throw', customMapping );
// returns [ 4, 8 ]
```

The function supports the following parameters:

-   **x**: input array.
-   **indices**: list of indices.
-   **mode**: index [mode][@stdlib/ndarray/base/ind].
-   **clbk**: function to apply.

### takeMap.assign( x, indices, mode, out, stride, offset, clbk )

> Takes elements from an array and assigns the values to elements in a provided output array.

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

var out = [ 0, 0, 0, 0, 0, 0 ];
var indices = [ 0, 0, 1, 1, 3, 3 ];

function clbk( val ) {
    return val * 2;
}

var arr = takeMap.assign( x, indices, 'throw', out, -1, out.length-1, clbk );
// returns [ 8, 8, 4, 4, 2, 2 ]

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

The function supports the following parameters:

-   **x**: input array.
-   **indices**: list of indices.
-   **mode**: index [mode][@stdlib/ndarray/base/ind].
-   **out**: output array.
-   **stride**: output array stride.
-   **offset**: output array offset.
-   **clbk**: callback function.

</section>

<!-- /.usage -->

<section class="notes">

</section>

<!-- /.notes -->

<section class="examples">

## Examples

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

```javascript
var filledBy = require( '@stdlib/array-base-filled-by' );
var discreteUniform = require( '@stdlib/random-base-discrete-uniform' );
var linspace = require( '@stdlib/array-base-linspace' );
var takeMap = require( '@stdlib/array-base-take-map' );

// Generate a linearly spaced array:
var x = linspace( 0, 100, 11 );
console.log( x );

// Generate an array of random indices:
var N = discreteUniform( 5, 15 );
var indices = filledBy( N, discreteUniform.factory( 0, x.length-1 ) );
console.log( indices );

// Define a mapping function (e.g., square the value):
function square( val ) {
    return val * val;
}

// Take a random sample of elements from `x` and apply the mapping function:
var y = takeMap( x, indices, 'throw', square );
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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[npm-url]: https://npmjs.org/package/@stdlib/array-base-take-map

[test-image]: https://github.com/stdlib-js/array-base-take-map/actions/workflows/test.yml/badge.svg?branch=v0.1.2
[test-url]: https://github.com/stdlib-js/array-base-take-map/actions/workflows/test.yml?query=branch:v0.1.2

[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/array-base-take-map/main.svg
[coverage-url]: https://codecov.io/github/stdlib-js/array-base-take-map?branch=main

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

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

[@stdlib/ndarray/base/ind]: https://www.npmjs.com/package/@stdlib/ndarray-base-ind

</section>

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