https://github.com/stdlib-js/stats-base-ndarray-max-by
Compute the maximum value of a one-dimensional ndarray via a callback function.
https://github.com/stdlib-js/stats-base-ndarray-max-by
domain extent extremes javascript math mathematics max maximum ndarray node node-js nodejs range statistics stats stdlib
Last synced: 3 months ago
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Compute the maximum value of a one-dimensional ndarray via a callback function.
- Host: GitHub
- URL: https://github.com/stdlib-js/stats-base-ndarray-max-by
- Owner: stdlib-js
- License: apache-2.0
- Created: 2025-06-04T02:21:10.000Z (4 months ago)
- Default Branch: main
- Last Pushed: 2025-06-09T07:30:54.000Z (4 months ago)
- Last Synced: 2025-06-09T08:35:18.018Z (4 months ago)
- Topics: domain, extent, extremes, javascript, math, mathematics, max, maximum, ndarray, node, node-js, nodejs, range, statistics, stats, stdlib
- Language: JavaScript
- Homepage: https://github.com/stdlib-js/stdlib
- Size: 418 KB
- Stars: 0
- Watchers: 0
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- Contributing: CONTRIBUTING.md
- License: LICENSE
- Code of conduct: CODE_OF_CONDUCT.md
- Citation: CITATION.cff
- Security: SECURITY.md
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README
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# maxBy
[![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url]
> Compute the maximum value of a one-dimensional ndarray via a callback function.
## Installation
```bash
npm install @stdlib/stats-base-ndarray-max-by
```
Alternatively,
- To load the package in a website via a `script` tag without installation and bundlers, use the [ES Module][es-module] available on the [`esm`][esm-url] branch (see [README][esm-readme]).
- If you are using Deno, visit the [`deno`][deno-url] branch (see [README][deno-readme] for usage intructions).
- For use in Observable, or in browser/node environments, use the [Universal Module Definition (UMD)][umd] build available on the [`umd`][umd-url] branch (see [README][umd-readme]).
The [branches.md][branches-url] file summarizes the available branches and displays a diagram illustrating their relationships.
To view installation and usage instructions specific to each branch build, be sure to explicitly navigate to the respective README files on each branch, as linked to above.
## Usage
```javascript
var maxBy = require( '@stdlib/stats-base-ndarray-max-by' );
```
#### maxBy( arrays, clbk\[, thisArg ] )
Computes the maximum value of a one-dimensional ndarray via a callback function.
```javascript
var ndarray = require( '@stdlib/ndarray-base-ctor' );
function clbk( value ) {
return value * 2.0;
}
var xbuf = [ 1.0, 3.0, 4.0, 2.0 ];
var x = new ndarray( 'generic', xbuf, [ 4 ], [ 1 ], 0, 'row-major' );
var v = maxBy( [ x ], clbk );
// returns 8.0
```
The function has the following parameters:
- **arrays**: array-like object containing a one-dimensional input ndarray.
- **clbk**: callback function.
- **thisArg**: callback execution context (_optional_).
The invoked callback is provided three arguments:
- **value**: current array element.
- **idx**: current array element index.
- **array**: input ndarray.
To set the callback execution context, provide a `thisArg`.
```javascript
var ndarray = require( '@stdlib/ndarray-base-ctor' );
function clbk( value ) {
this.count += 1;
return value * 2.0;
}
var xbuf = [ 1.0, 3.0, 4.0, 2.0 ];
var x = new ndarray( 'generic', xbuf, [ 4 ], [ 1 ], 0, 'row-major' );
var ctx = {
'count': 0
};
var v = maxBy( [ x ], clbk, ctx );
// returns 8.0
var count = ctx.count;
// returns 4
```
## Notes
- If provided an empty one-dimensional ndarray, 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**.
## Examples
```javascript
var discreteUniform = require( '@stdlib/random-array-discrete-uniform' );
var ndarray = require( '@stdlib/ndarray-base-ctor' );
var ndarray2array = require( '@stdlib/ndarray-to-array' );
var maxBy = require( '@stdlib/stats-base-ndarray-max-by' );
function clbk( value ) {
return value * 2.0;
}
var xbuf = discreteUniform( 10, -50, 50, {
'dtype': 'generic'
});
var x = new ndarray( 'generic', xbuf, [ xbuf.length ], [ 1 ], 0, 'row-major' );
console.log( ndarray2array( x ) );
var v = maxBy( [ x ], clbk );
console.log( v );
```
* * *
## 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 © 2016-2025. The Stdlib [Authors][stdlib-authors].
[npm-image]: http://img.shields.io/npm/v/@stdlib/stats-base-ndarray-max-by.svg
[npm-url]: https://npmjs.org/package/@stdlib/stats-base-ndarray-max-by
[test-image]: https://github.com/stdlib-js/stats-base-ndarray-max-by/actions/workflows/test.yml/badge.svg?branch=main
[test-url]: https://github.com/stdlib-js/stats-base-ndarray-max-by/actions/workflows/test.yml?query=branch:main
[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/stats-base-ndarray-max-by/main.svg
[coverage-url]: https://codecov.io/github/stdlib-js/stats-base-ndarray-max-by?branch=main
[chat-image]: https://img.shields.io/gitter/room/stdlib-js/stdlib.svg
[chat-url]: https://app.gitter.im/#/room/#stdlib-js_stdlib:gitter.im
[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-base-ndarray-max-by/tree/deno
[deno-readme]: https://github.com/stdlib-js/stats-base-ndarray-max-by/blob/deno/README.md
[umd-url]: https://github.com/stdlib-js/stats-base-ndarray-max-by/tree/umd
[umd-readme]: https://github.com/stdlib-js/stats-base-ndarray-max-by/blob/umd/README.md
[esm-url]: https://github.com/stdlib-js/stats-base-ndarray-max-by/tree/esm
[esm-readme]: https://github.com/stdlib-js/stats-base-ndarray-max-by/blob/esm/README.md
[branches-url]: https://github.com/stdlib-js/stats-base-ndarray-max-by/blob/main/branches.md
[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/stats-base-ndarray-max-by/main/LICENSE