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

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<details>
  <summary>
    About stdlib...
  </summary>
  <p>We believe in a future in which the web is a preferred environment for numerical computation. To help realize this future, we've built stdlib. stdlib is a standard library, with an emphasis on numerical and scientific computation, written in JavaScript (and C) for execution in browsers and in Node.js.</p>
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# rangeBy

[![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 [range][range] of an array via a callback function.

<section class="intro">

The [**range**][range] is defined as the difference between the maximum and minimum values.

</section>

<!-- /.intro -->

<section class="installation">

## Installation

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

</section>

<section class="usage">

## Usage

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

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

Computes the [range][range] 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 = rangeBy( x, accessor );
// returns 18.0
```

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 = rangeBy( x, accessor, context );
// returns 18.0

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 rangeBy = require( '@stdlib/stats-array-range-by' );

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

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

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

</section>

<!-- /.examples -->

<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. -->

<section class="related">

</section>

<!-- /.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

[![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-image]: http://img.shields.io/npm/v/@stdlib/stats-array-range-by.svg
[npm-url]: https://npmjs.org/package/@stdlib/stats-array-range-by

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

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

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

[stdlib-authors]: https://github.com/stdlib-js/stdlib/graphs/contributors

[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-range-by/tree/deno
[deno-readme]: https://github.com/stdlib-js/stats-array-range-by/blob/deno/README.md
[umd-url]: https://github.com/stdlib-js/stats-array-range-by/tree/umd
[umd-readme]: https://github.com/stdlib-js/stats-array-range-by/blob/umd/README.md
[esm-url]: https://github.com/stdlib-js/stats-array-range-by/tree/esm
[esm-readme]: https://github.com/stdlib-js/stats-array-range-by/blob/esm/README.md
[branches-url]: https://github.com/stdlib-js/stats-array-range-by/blob/main/branches.md

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

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

[range]: https://en.wikipedia.org/wiki/Range_%28statistics%29

</section>

<!-- /.links -->