https://github.com/stdlib-js/ndarray-base-maybe-broadcast-array
Broadcast an ndarray to a specified shape if and only if the specified shape differs from the provided ndarray's shape.
https://github.com/stdlib-js/ndarray-base-maybe-broadcast-array
array base broadcast broadcasting javascript multidimensional ndarray node node-js nodejs reshape stdlib types util utilities utility utils
Last synced: 9 months ago
JSON representation
Broadcast an ndarray to a specified shape if and only if the specified shape differs from the provided ndarray's shape.
- Host: GitHub
- URL: https://github.com/stdlib-js/ndarray-base-maybe-broadcast-array
- Owner: stdlib-js
- License: apache-2.0
- Created: 2022-01-26T00:40:36.000Z (almost 4 years ago)
- Default Branch: main
- Last Pushed: 2025-03-10T01:53:39.000Z (10 months ago)
- Last Synced: 2025-03-27T01:46:43.313Z (9 months ago)
- Topics: array, base, broadcast, broadcasting, javascript, multidimensional, ndarray, node, node-js, nodejs, reshape, stdlib, types, util, utilities, utility, utils
- Language: JavaScript
- Homepage: https://github.com/stdlib-js/stdlib
- Size: 1.43 MB
- Stars: 2
- Watchers: 3
- 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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# maybeBroadcastArray
[![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url]
> Broadcast an [ndarray][@stdlib/ndarray/base/ctor] to a specified shape if and only if the specified shape differs from the provided [ndarray][@stdlib/ndarray/base/ctor]'s shape.
## Installation
```bash
npm install @stdlib/ndarray-base-maybe-broadcast-array
```
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 maybeBroadcastArray = require( '@stdlib/ndarray-base-maybe-broadcast-array' );
```
#### maybeBroadcastArray( arr, shape )
Broadcasts an [ndarray][@stdlib/ndarray/base/ctor] to a specified `shape` if and only if the specified `shape` differs from the provided [ndarray][@stdlib/ndarray/base/ctor]'s shape.
```javascript
var array = require( '@stdlib/ndarray-array' );
// Create a 2x2 ndarray:
var x = array( [ [ 1, 2 ], [ 3, 4 ] ] );
// returns
// Broadcast to a 2x2x2 ndarray:
var y = maybeBroadcastArray( x, [ 2, 2, 2 ] );
// returns
```
## Notes
- The function throws an error if a provided [ndarray][@stdlib/ndarray/base/ctor] is [incompatible][@stdlib/ndarray/base/broadcast-shapes] with a provided shape.
- If a provided [ndarray][@stdlib/ndarray/base/ctor] has the same shape as the specified shape, the function returns the provided [ndarray][@stdlib/ndarray/base/ctor].
- If a provided [ndarray][@stdlib/ndarray/base/ctor] has a different (broadcast compatible) shape than the specified shape, the function returns a new (base) [ndarray][@stdlib/ndarray/base/ctor] view of the provided [ndarray][@stdlib/ndarray/base/ctor]'s data. The view is typically **not** contiguous. As more than one element of a returned view may refer to the same memory location, writing to the view may affect multiple elements. If you need to write to the returned [ndarray][@stdlib/ndarray/base/ctor], copy the [ndarray][@stdlib/ndarray/base/ctor] **before** performing operations which may mutate elements.
- A returned [ndarray][@stdlib/ndarray/base/ctor] is a "base" [ndarray][@stdlib/ndarray/base/ctor], and, thus, a returned [ndarray][@stdlib/ndarray/base/ctor] view does not perform bounds checking or afford any of the guarantees of the non-base [ndarray][@stdlib/ndarray/ctor] constructor. The primary intent of this function is to broadcast an ndarray-like object within internal implementations and to do so with minimal overhead.
## Examples
```javascript
var array = require( '@stdlib/ndarray-array' );
var numel = require( '@stdlib/ndarray-base-numel' );
var ind2sub = require( '@stdlib/ndarray-ind2sub' );
var maybeBroadcastArray = require( '@stdlib/ndarray-base-maybe-broadcast-array' );
// Create a 2x2 array:
var x = array( [ [ 1, 2 ], [ 3, 4 ] ] );
// returns
// Broadcast the array to 3x2x2:
var y = maybeBroadcastArray( x, [ 3, 2, 2 ] );
// returns
// Retrieve the shape:
var sh = y.shape;
// returns [ 3, 2, 2 ]
// Retrieve the number of elements:
var N = numel( sh );
// Loop through the array elements...
var i;
for ( i = 0; i < N; i++ ) {
console.log( 'Y[%s] = %d', ind2sub( sh, i ).join( ', ' ), y.iget( i ) );
}
```
* * *
## 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/ndarray-base-maybe-broadcast-array.svg
[npm-url]: https://npmjs.org/package/@stdlib/ndarray-base-maybe-broadcast-array
[test-image]: https://github.com/stdlib-js/ndarray-base-maybe-broadcast-array/actions/workflows/test.yml/badge.svg?branch=main
[test-url]: https://github.com/stdlib-js/ndarray-base-maybe-broadcast-array/actions/workflows/test.yml?query=branch:main
[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/ndarray-base-maybe-broadcast-array/main.svg
[coverage-url]: https://codecov.io/github/stdlib-js/ndarray-base-maybe-broadcast-array?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/ndarray-base-maybe-broadcast-array/tree/deno
[deno-readme]: https://github.com/stdlib-js/ndarray-base-maybe-broadcast-array/blob/deno/README.md
[umd-url]: https://github.com/stdlib-js/ndarray-base-maybe-broadcast-array/tree/umd
[umd-readme]: https://github.com/stdlib-js/ndarray-base-maybe-broadcast-array/blob/umd/README.md
[esm-url]: https://github.com/stdlib-js/ndarray-base-maybe-broadcast-array/tree/esm
[esm-readme]: https://github.com/stdlib-js/ndarray-base-maybe-broadcast-array/blob/esm/README.md
[branches-url]: https://github.com/stdlib-js/ndarray-base-maybe-broadcast-array/blob/main/branches.md
[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/ndarray-base-maybe-broadcast-array/main/LICENSE
[@stdlib/ndarray/ctor]: https://github.com/stdlib-js/ndarray-ctor
[@stdlib/ndarray/base/ctor]: https://github.com/stdlib-js/ndarray-base-ctor
[@stdlib/ndarray/base/broadcast-shapes]: https://github.com/stdlib-js/ndarray-base-broadcast-shapes