https://github.com/stdlib-js/stats-min-by

Compute the minimum value along one or more ndarray dimensions according to a callback function.
https://github.com/stdlib-js/stats-min-by

domain extent extremes javascript math mathematics min minimum ndarray node node-js nodejs range statistics stats stdlib

Last synced: about 2 months ago
JSON representation

Compute the minimum value along one or more ndarray dimensions according to a callback function.

Host: GitHub
URL: https://github.com/stdlib-js/stats-min-by
Owner: stdlib-js
License: apache-2.0
Created: 2025-08-09T09:35:12.000Z (10 months ago)
Default Branch: main
Last Pushed: 2026-04-11T03:43:27.000Z (2 months ago)
Last Synced: 2026-04-11T05:30:36.438Z (2 months ago)
Topics: domain, extent, extremes, javascript, math, mathematics, min, minimum, ndarray, node, node-js, nodejs, range, statistics, stats, stdlib
Language: JavaScript
Homepage: https://github.com/stdlib-js/stdlib
Size: 3.65 MB
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
- Notice: NOTICE

Awesome Lists containing this project

README

          

  

    About stdlib...

  

  
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.

  The library is fully decomposable, being architected in such a way that you can swap out and mix and match APIs and functionality to cater to your exact preferences and use cases.

  When you use stdlib, you can be absolutely certain that you are using the most thorough, rigorous, well-written, studied, documented, tested, measured, and high-quality code out there.

  To join us in bringing numerical computing to the web, get started by checking us out on GitHub, and please consider financially supporting stdlib. We greatly appreciate your continued support!


# minBy

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

> Compute the minimum value along one or more [ndarray][@stdlib/ndarray/ctor] dimensions according to a callback function.

## Installation

```bash

npm install @stdlib/stats-min-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 minBy = require( '@stdlib/stats-min-by' );

```

#### minBy( x\[, options], clbk\[, thisArg] )

Computes the minimum value along one or more [ndarray][@stdlib/ndarray/ctor] dimensions according to a callback function.

```javascript

var array = require( '@stdlib/ndarray-array' );

var x = array( [ -1.0, 2.0, -3.0 ] );

function clbk( v ) {

    return v * 2.0;

}

var y = minBy( x, clbk );

// returns [ -6.0 ]

```

The function has the following parameters:

-   **x**: input [ndarray][@stdlib/ndarray/ctor].

-   **options**: function options (_optional_).

-   **clbk**: callback function.

-   **thisArg**: callback function execution context (_optional_).

The invoked callback is provided three arguments:

-   **value**: current array element.

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

-   **array**: input ndarray.

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

```javascript

var array = require( '@stdlib/ndarray-array' );

var x = array( [ -1.0, 2.0, -3.0 ] );

function clbk( v ) {

    this.count += 1;

    return v * 2.0;

}

var ctx = {

    'count': 0

};

var y = minBy( x, clbk, ctx );

// returns [ -6.0 ]

var count = ctx.count;

// returns 3

```

The function accepts the following options:

-   **dims**: list of dimensions over which to perform a reduction. If not provided, the function performs a reduction over all elements in a provided input [ndarray][@stdlib/ndarray/ctor].

-   **dtype**: output ndarray [data type][@stdlib/ndarray/dtypes]. Must be a real-valued or "generic" [data type][@stdlib/ndarray/dtypes].

-   **keepdims**: boolean indicating whether the reduced dimensions should be included in the returned [ndarray][@stdlib/ndarray/ctor] as singleton dimensions. Default: `false`.

By default, the function performs a reduction over all elements in a provided input [ndarray][@stdlib/ndarray/ctor]. To perform a reduction over specific dimensions, provide a `dims` option.

```javascript

var array = require( '@stdlib/ndarray-array' );

function clbk( v ) {

    return v * 100.0;

}

var x = array( [ -1.0, 2.0, -3.0, 4.0 ], {

    'shape': [ 2, 2 ],

    'order': 'row-major'

});

// returns [ [ -1.0, 2.0 ], [ -3.0, 4.0 ] ]

var opts = {

    'dims': [ 0 ]

};

var y = minBy( x, opts, clbk );

// returns [ -300.0, 200.0 ]

opts = {

    'dims': [ 1 ]

};

y = minBy( x, opts, clbk );

// returns [ -100.0, -300.0 ]

opts = {

    'dims': [ 0, 1 ]

};

y = minBy( x, opts, clbk );

// returns [ -300.0 ]

```

By default, the function excludes reduced dimensions from the output [ndarray][@stdlib/ndarray/ctor]. To include the reduced dimensions as singleton dimensions, set the `keepdims` option to `true`.

```javascript

var array = require( '@stdlib/ndarray-array' );

function clbk( v ) {

    return v * 100.0;

}

var x = array( [ -1.0, 2.0, -3.0, 4.0 ], {

    'shape': [ 2, 2 ],

    'order': 'row-major'

});

// returns [ [ -1.0, 2.0 ], [ -3.0, 4.0 ] ]

var opts = {

    'dims': [ 0 ],

    'keepdims': true

};

var y = minBy( x, opts, clbk );

// returns [ [ -300.0, 200.0 ] ]

opts = {

    'dims': [ 1 ],

    'keepdims': true

};

y = minBy( x, opts, clbk );

// returns [ [ -100.0 ], [ -300.0 ] ]

opts = {

    'dims': [ 0, 1 ],

    'keepdims': true

};

y = minBy( x, opts, clbk );

// returns [ [ -300.0 ] ]

```

By default, the function returns an [ndarray][@stdlib/ndarray/ctor] having a [data type][@stdlib/ndarray/dtypes] determined by the function's output data type [policy][@stdlib/ndarray/output-dtype-policies]. To override the default behavior, set the `dtype` option.

```javascript

var getDType = require( '@stdlib/ndarray-dtype' );

var array = require( '@stdlib/ndarray-array' );

function clbk( v ) {

    return v * 100.0;

}

var x = array( [ -1.0, 2.0, -3.0 ], {

    'dtype': 'generic'

});

var opts = {

    'dtype': 'float64'

};

var y = minBy( x, opts, clbk );

// returns 

var dt = String( getDType( y ) );

// returns 'float64'

```

#### minBy.assign( x, out\[, options], clbk\[, thisArg] )

Computes the minimum value along one or more [ndarray][@stdlib/ndarray/ctor] dimensions according to a callback function and assigns results to a provided output [ndarray][@stdlib/ndarray/ctor].

```javascript

var array = require( '@stdlib/ndarray-array' );

var zeros = require( '@stdlib/ndarray-zeros' );

function clbk( v ) {

    return v * 100.0;

}

var x = array( [ -1.0, 2.0, -3.0 ] );

var y = zeros( [] );

var out = minBy.assign( x, y, clbk );

// returns [ -300.0 ]

var bool = ( out === y );

// returns true

```

The method has the following parameters:

-   **x**: input [ndarray][@stdlib/ndarray/ctor].

-   **out**: output [ndarray][@stdlib/ndarray/ctor].

-   **options**: function options (_optional_).

-   **clbk**: callback function.

-   **thisArg**: callback execution context (_optional_).

The method accepts the following options:

-   **dims**: list of dimensions over which to perform a reduction. If not provided, the function performs a reduction over all elements in a provided input [ndarray][@stdlib/ndarray/ctor].

## Notes

-   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**.

-   Setting the `keepdims` option to `true` can be useful when wanting to ensure that the output [ndarray][@stdlib/ndarray/ctor] is [broadcast-compatible][@stdlib/ndarray/base/broadcast-shapes] with ndarrays having the same shape as the input [ndarray][@stdlib/ndarray/ctor].

-   The output data type [policy][@stdlib/ndarray/output-dtype-policies] only applies to the main function and specifies that, by default, the function must return an [ndarray][@stdlib/ndarray/ctor] having a real-valued or "generic" [data type][@stdlib/ndarray/dtypes]. For the `assign` method, the output [ndarray][@stdlib/ndarray/ctor] is allowed to have any supported output [data type][@stdlib/ndarray/dtypes].

## Examples

```javascript

var filledarrayBy = require( '@stdlib/array-filled-by' );

var discreteUniform = require( '@stdlib/random-base-discrete-uniform' );

var getDType = require( '@stdlib/ndarray-dtype' );

var ndarray2array = require( '@stdlib/ndarray-to-array' );

var ndarray = require( '@stdlib/ndarray-ctor' );

var minBy = require( '@stdlib/stats-min-by' );

// Define a function for generating an object having a random value:

function random() {

    return {

        'value': discreteUniform( 0, 20 )

    };

}

// Generate an array of random objects:

var xbuf = filledarrayBy( 25, 'generic', random );

// Wrap in an ndarray:

var x = new ndarray( 'generic', xbuf, [ 5, 5 ], [ 5, 1 ], 0, 'row-major' );

console.log( ndarray2array( x ) );

// Define an accessor function:

function accessor( v ) {

    return v.value * 100;

}

// Perform a reduction:

var opts = {

    'dims': [ 0 ]

};

var y = minBy( x, opts, accessor );

// Resolve the output array data type:

var dt = getDType( y );

console.log( dt );

// Print the results:

console.log( ndarray2array( y ) );

```

* * *

## 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 © 2016-2026. The Stdlib [Authors][stdlib-authors].

[npm-image]: http://img.shields.io/npm/v/@stdlib/stats-min-by.svg

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

[test-image]: https://github.com/stdlib-js/stats-min-by/actions/workflows/test.yml/badge.svg?branch=main

[test-url]: https://github.com/stdlib-js/stats-min-by/actions/workflows/test.yml?query=branch:main

[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/stats-min-by/main.svg

[coverage-url]: https://codecov.io/github/stdlib-js/stats-min-by?branch=main

[chat-image]: https://img.shields.io/badge/zulip-join_chat-brightgreen.svg

[chat-url]: https://stdlib.zulipchat.com

[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-min-by/tree/deno

[deno-readme]: https://github.com/stdlib-js/stats-min-by/blob/deno/README.md

[umd-url]: https://github.com/stdlib-js/stats-min-by/tree/umd

[umd-readme]: https://github.com/stdlib-js/stats-min-by/blob/umd/README.md

[esm-url]: https://github.com/stdlib-js/stats-min-by/tree/esm

[esm-readme]: https://github.com/stdlib-js/stats-min-by/blob/esm/README.md

[branches-url]: https://github.com/stdlib-js/stats-min-by/blob/main/branches.md

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

[@stdlib/ndarray/ctor]: https://github.com/stdlib-js/ndarray-ctor

[@stdlib/ndarray/dtypes]: https://github.com/stdlib-js/ndarray-dtypes

[@stdlib/ndarray/output-dtype-policies]: https://github.com/stdlib-js/ndarray-output-dtype-policies

[@stdlib/ndarray/base/broadcast-shapes]: https://github.com/stdlib-js/ndarray-base-broadcast-shapes

ecosyste.ms

Data

Tools

Indexes

Applications

Experiments

Awesome

https://github.com/stdlib-js/stats-min-by

Awesome Lists containing this project

README