https://github.com/stdlib-js/ndarray-any-by
Test whether at least one element along one or more ndarray dimensions passes a test implemented by a predicate function.
https://github.com/stdlib-js/ndarray-any-by
any array javascript ndarray node node-js nodejs one reduce reduction some stdlib strided truthy utils
Last synced: 24 days ago
JSON representation
Test whether at least one element along one or more ndarray dimensions passes a test implemented by a predicate function.
- Host: GitHub
- URL: https://github.com/stdlib-js/ndarray-any-by
- Owner: stdlib-js
- License: apache-2.0
- Created: 2025-09-23T00:50:39.000Z (9 months ago)
- Default Branch: main
- Last Pushed: 2026-04-17T11:16:54.000Z (about 2 months ago)
- Last Synced: 2026-04-17T12:32:18.269Z (about 2 months ago)
- Topics: any, array, javascript, ndarray, node, node-js, nodejs, one, reduce, reduction, some, stdlib, strided, truthy, utils
- Language: JavaScript
- Homepage: https://github.com/stdlib-js/stdlib
- Size: 1.67 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!
# anyBy
[![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url]
> Test whether at least one element along one or more [`ndarray`][@stdlib/ndarray/ctor] dimensions passes a test implemented by a predicate function.
## Installation
```bash
npm install @stdlib/ndarray-any-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 anyBy = require( '@stdlib/ndarray-any-by' );
```
#### anyBy( x\[, options], predicate\[, thisArg] )
Tests whether at least one element along one or more [`ndarray`][@stdlib/ndarray/ctor] dimensions passes a test implemented by a predicate function.
```javascript
var array = require( '@stdlib/ndarray-array' );
function isPositive( value ) {
return value > 0.0;
}
// Create an input ndarray:
var x = array( [ [ 1.0, -2.0 ], [ 3.0, -4.0 ] ] );
// Test whether at least one element is positive:
var out = anyBy( x, isPositive );
// returns [ true ]
```
The function accepts the following arguments:
- **x**: input [`ndarray`][@stdlib/ndarray/ctor].
- **options**: function options _(optional)_.
- **predicate**: predicate function.
- **thisArg**: predicate function execution context _(optional)_.
The function accepts the following options:
- **dims**: list of dimensions over which to perform a reduction.
- **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 [`ndarray`][@stdlib/ndarray/ctor]. To reduce specific dimensions, set the `dims` option.
```javascript
var array = require( '@stdlib/ndarray-array' );
function isPositive( value ) {
return value > 0.0;
}
// Create an input ndarray:
var x = array( [ [ 1.0, 2.0 ], [ -3.0, -4.0 ] ] );
// returns
var opts = {
'dims': [ 1 ]
};
// Perform reduction:
var out = anyBy( x, opts, isPositive );
// returns [ true, false ]
```
By default, the function returns an [`ndarray`][@stdlib/ndarray/ctor] having a shape matching only the non-reduced dimensions of the input [`ndarray`][@stdlib/ndarray/ctor] (i.e., the reduced dimensions are dropped). To include the reduced dimensions as singleton dimensions in the output [`ndarray`][@stdlib/ndarray/ctor], set the `keepdims` option to `true`.
```javascript
var array = require( '@stdlib/ndarray-array' );
function isPositive( value ) {
return value > 0.0;
}
// Create an input ndarray:
var x = array( [ [ 1.0, 2.0 ], [ -3.0, -4.0 ] ] );
var opts = {
'keepdims': true
};
// Perform reduction:
var out = anyBy( x, opts, isPositive );
// returns [ [ true ] ]
```
To set the function execution context, provide a `thisArg`.
```javascript
var array = require( '@stdlib/ndarray-array' );
function isPositive( value ) {
this.count += 1;
return value > 0.0;
}
// Create an input ndarray:
var x = array( [ [ -1.0, -2.0 ], [ -3.0, 4.0 ] ] );
// returns
// Create a context object:
var ctx = {
'count': 0
};
// Perform reduction:
var out = anyBy( x, isPositive, ctx );
// returns [ true ]
var count = ctx.count;
// returns 4
```
#### anyBy.assign( x, y\[, options], predicate\[, thisArg] )
Tests whether at least one element along one or more [`ndarray`][@stdlib/ndarray/ctor] dimensions passes a test implemented by a predicate function and assigns the result to a provided output [`ndarray`][@stdlib/ndarray/ctor].
```javascript
var array = require( '@stdlib/ndarray-array' );
var empty = require( '@stdlib/ndarray-empty' );
function isPositive( value ) {
return value > 0.0;
}
// Create an input ndarray:
var x = array( [ [ 1.0, -2.0 ], [ 3.0, -4.0 ] ] );
// Create an output ndarray:
var y = empty( [], {
'dtype': 'bool'
});
// Perform reduction:
var out = anyBy.assign( x, y, isPositive );
// returns [ true ]
var bool = ( out === y );
// returns true
```
The function accepts the following arguments:
- **x**: input [`ndarray`][@stdlib/ndarray/ctor].
- **y**: output [`ndarray`][@stdlib/ndarray/ctor]. The output [`ndarray`][@stdlib/ndarray/ctor] must have a shape matching the non-reduced dimensions of the input [`ndarray`][@stdlib/ndarray/ctor].
- **options**: function options _(optional)_.
- **predicate**: predicate function.
- **thisArg**: predicate function execution context _(optional)_.
The function accepts the following options:
- **dims**: list of dimensions over which to perform a reduction.
By default, the function performs a reduction over all elements in a provided [`ndarray`][@stdlib/ndarray/ctor]. To reduce specific dimensions, set the `dims` option.
```javascript
var array = require( '@stdlib/ndarray-array' );
var empty = require( '@stdlib/ndarray-empty' );
function predicate( value ) {
return value > 0.0;
}
// Create an input ndarray:
var x = array( [ [ 1.0, 2.0 ], [ -3.0, -4.0 ] ] );
// returns
// Create an output ndarray:
var y = empty( [ 2 ], {
'dtype': 'bool'
});
var opts = {
'dims': [ 1 ]
};
// Perform reduction:
var out = anyBy.assign( x, y, opts, predicate );
// returns [ true, false ]
var bool = ( out === y );
// returns true
```
## Notes
- The predicate function is provided the following arguments:
- **value**: current array element.
- **indices**: current array element indices.
- **arr**: the input ndarray.
## Examples
```javascript
var discreteUniform = require( '@stdlib/random-base-discrete-uniform' ).factory;
var isEven = require( '@stdlib/assert-is-even' ).isPrimitive;
var ndarray2array = require( '@stdlib/ndarray-to-array' );
var fillBy = require( '@stdlib/ndarray-fill-by' );
var zeros = require( '@stdlib/ndarray-zeros' );
var anyBy = require( '@stdlib/ndarray-any-by' );
var x = zeros( [ 2, 4, 5 ], {
'dtype': 'float64'
});
x = fillBy( x, discreteUniform( 0, 10 ) );
console.log( ndarray2array( x ) );
var y = anyBy( x, isEven );
console.log( y.get() );
```
* * *
## 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/ndarray-any-by.svg
[npm-url]: https://npmjs.org/package/@stdlib/ndarray-any-by
[test-image]: https://github.com/stdlib-js/ndarray-any-by/actions/workflows/test.yml/badge.svg?branch=main
[test-url]: https://github.com/stdlib-js/ndarray-any-by/actions/workflows/test.yml?query=branch:main
[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/ndarray-any-by/main.svg
[coverage-url]: https://codecov.io/github/stdlib-js/ndarray-any-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/ndarray-any-by/tree/deno
[deno-readme]: https://github.com/stdlib-js/ndarray-any-by/blob/deno/README.md
[umd-url]: https://github.com/stdlib-js/ndarray-any-by/tree/umd
[umd-readme]: https://github.com/stdlib-js/ndarray-any-by/blob/umd/README.md
[esm-url]: https://github.com/stdlib-js/ndarray-any-by/tree/esm
[esm-readme]: https://github.com/stdlib-js/ndarray-any-by/blob/esm/README.md
[branches-url]: https://github.com/stdlib-js/ndarray-any-by/blob/main/branches.md
[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/ndarray-any-by/main/LICENSE
[@stdlib/ndarray/ctor]: https://github.com/stdlib-js/ndarray-ctor