npm package: @stdlib/stats-array-max-by
Description: Calculate the maximum value of an array via a callback function.
Author: The Stdlib Authors
Latest version: 0.1.1

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<details>
  <summary>
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# maxBy

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

> Calculate the maximum value of an array via a callback function.

<section class="intro">

</section>

<!-- /.intro -->

<section class="installation">

## Installation

```bash
npm install @stdlib/stats-array-max-by
```

</section>

<section class="usage">

## Usage

```javascript
var maxBy = require( '@stdlib/stats-array-max-by' );
```

#### maxBy( x, clbk\[, thisArg] )

Computes the maximum value of an array via a callback function.

```javascript
function accessor( v ) {
    return v * 2.0;
}

var x = [ -2.0, 1.0, 3.0, -5.0, 4.0, 0.0, -1.0, -3.0 ];

var v = maxBy( x, accessor );
// returns 8.0
```

The function has the following parameters:

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

The invoked callback is provided three arguments:

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

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

```javascript
function accessor( v ) {
    this.count += 1;
    return v * 2.0;
}

var x = [ -2.0, 1.0, 3.0, -5.0, 4.0, 0.0, -1.0, -3.0 ];

var context = {
    'count': 0
};

var v = maxBy( x, accessor, context );
// returns 8.0

var cnt = context.count;
// returns 8
```

</section>

<!-- /.usage -->

<section class="notes">

## Notes

-   If provided an empty array, the function returns `NaN`.
-   A provided callback function should return a numeric value.
-   If a provided callback function does not return any value (or equivalently, explicitly returns `undefined`), the value is **ignored**.
-   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 maxBy = require( '@stdlib/stats-array-max-by' );

function accessor( v ) {
    return v * 2.0;
}

var x = discreteUniform( 10, -50, 50, {
    'dtype': 'float64'
});
console.log( x );

var v = maxBy( x, accessor );
console.log( v );
```

</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>

<!-- /.stdlib -->

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[npm-url]: https://npmjs.org/package/@stdlib/stats-array-max-by

[test-image]: https://github.com/stdlib-js/stats-array-max-by/actions/workflows/test.yml/badge.svg?branch=v0.1.1
[test-url]: https://github.com/stdlib-js/stats-array-max-by/actions/workflows/test.yml?query=branch:v0.1.1

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

[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/stats-array-max-by/main/LICENSE

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

</section>

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