npm package: @stdlib/array-base-map
Description: Apply a callback function to elements in an input array and assign results to elements in a new output array.
Author: The Stdlib Authors
Latest version: 0.1.1

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  <summary>
    About stdlib...
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</details>

# map

[![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 callback function to elements in an input array and assign results to elements in a new output array.

<!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. -->

<section class="intro">

</section>

<!-- /.intro -->

<!-- Package usage documentation. -->

<section class="installation">

## Installation

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

</section>

<section class="usage">

## Usage

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

#### map( x, fcn\[, thisArg] )

Applies a callback function to elements in an input array and assigns results to elements in a new 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 y = map( x, naryFunction( abs, 1 ) );
// returns [ 1.0, 2.0, 3.0, 4.0 ]
```

The function accepts the following arguments:

-   **x**: input array.
-   **fcn**: callback function.
-   **thisArg**: callback execution context (_optional_).

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

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

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

var x = [ 1.0, 2.0, 3.0, 4.0 ];

var ctx = {
    'count': 0
};

var y = map( x, count, ctx );
// returns [ 1.0, 2.0, 3.0, 4.0 ]

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

The callback function is provided the following arguments:

-   **value**: current array element.
-   **index**: current element index.
-   **arr**: input array.

#### map.assign( x, y, stride, offset, fcn\[, thisArg] )

Applies a callback function to elements in an input array and assigns results to elements in an output array.

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

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

var y = zeros( x.length );

var out = map.assign( x, y, 1, 0, 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 array.
-   **y**: output array.
-   **stride**: stride length for output array.
-   **offset**: starting index for output array.
-   **fcn**: callback function.
-   **thisArg**: callback execution context (_optional_).

</section>

<!-- /.usage -->

<!-- Package usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->

<section class="notes">

## Notes

-   If provided an array-like object having a `map` method, the function defers execution to that method and assumes that the method API has the following signature:

    ```text
    x.map( fcn, thisArg )
    ```

-   The function supports array-like objects having getter and setter accessors for array element access (e.g., [`@stdlib/array-base/accessor`][@stdlib/array/base/accessor]).

</section>

<!-- /.notes -->

<section class="examples">

## Examples

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

```javascript
var discreteUniform = require( '@stdlib/random-array-discrete-uniform' );
var naryFunction = require( '@stdlib/utils-nary-function' );
var abs = require( '@stdlib/math-base-special-abs' );
var map = require( '@stdlib/array-base-map' );

var x = discreteUniform( 10, -10, 10, {
    'dtype': 'float64'
});

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

</section>

<!-- /.examples -->

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<section class="references">

</section>

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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-map

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[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/array-base-map/main.svg
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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-map/tree/deno
[deno-readme]: https://github.com/stdlib-js/array-base-map/blob/deno/README.md
[umd-url]: https://github.com/stdlib-js/array-base-map/tree/umd
[umd-readme]: https://github.com/stdlib-js/array-base-map/blob/umd/README.md
[esm-url]: https://github.com/stdlib-js/array-base-map/tree/esm
[esm-readme]: https://github.com/stdlib-js/array-base-map/blob/esm/README.md
[branches-url]: https://github.com/stdlib-js/array-base-map/blob/main/branches.md

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

[@stdlib/array/base/accessor]: https://www.npmjs.com/package/@stdlib/array-base-accessor

</section>

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