npm package: @stdlib/ndarray-base-maybe-broadcast-array
Description: Broadcast an ndarray to a specified shape if and only if the specified shape differs from the provided ndarray's shape.
Author: The Stdlib Authors
Latest version: 0.2.5

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# maybeBroadcastArray

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

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<section class="intro">

</section>

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<!-- Package usage documentation. -->

<section class="installation">

## Installation

```bash
npm install @stdlib/ndarray-base-maybe-broadcast-array
```

</section>

<section class="usage">

## 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 <ndarray>

// Broadcast to a 2x2x2 ndarray:
var y = maybeBroadcastArray( x, [ 2, 2, 2 ] );
// returns <ndarray>
```

</section>

<!-- /.usage -->

<!-- Package usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->

<section class="notes">

## 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.

</section>

<!-- /.notes -->

<!-- Package usage examples. -->

<section class="examples">

## Examples

<!-- eslint no-undef: "error" -->

```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 <ndarray>

// Broadcast the array to 3x2x2:
var y = maybeBroadcastArray( x, [ 3, 2, 2 ] );
// returns <ndarray>

// 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 ) );
}
```

</section>

<!-- /.examples -->

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</section>

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* * *

## 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].

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## License

See [LICENSE][stdlib-license].


## Copyright

Copyright &copy; 2016-2026. The Stdlib [Authors][stdlib-authors].

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