npm package: @stdlib/ndarray-maybe-broadcast-arrays
Description: Broadcast ndarrays to a common shape.
Author: The Stdlib Authors
Latest version: 0.2.3

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# maybeBroadcastArrays

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

> Broadcast [ndarrays][@stdlib/ndarray/ctor] to a common shape.

<!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. -->

<section class="intro">

</section>

<!-- /.intro -->

<!-- Package usage documentation. -->

<section class="installation">

## Installation

```bash
npm install @stdlib/ndarray-maybe-broadcast-arrays
```

</section>

<section class="usage">

## Usage

```javascript
var maybeBroadcastArrays = require( '@stdlib/ndarray-maybe-broadcast-arrays' );
```

#### maybeBroadcastArrays( arrays )

Broadcasts [ndarrays][@stdlib/ndarray/ctor] to a common shape.

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

// Create a 2x2 ndarray:
var x = array( [ [ 1, 2 ], [ 3, 4 ] ] );
// returns <ndarray>

// Create a 2x2x2 ndarray:
var y = zeros( [ 2, 2, 2 ] );
// returns <ndarray>

// Broadcast to a common shape:
var out = maybeBroadcastArrays( [ x, y ] );
// returns [ <ndarray>, <ndarray> ]
```

The function supports two (mutually exclusive) means for providing [ndarray][@stdlib/ndarray/ctor] arguments:

1.  providing a single array of [ndarray][@stdlib/ndarray/ctor] arguments.
2.  providing [ndarray][@stdlib/ndarray/ctor] arguments as separate arguments.

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

// Create a 2x2 ndarray:
var x = array( [ [ 1, 2 ], [ 3, 4 ] ] );
// returns <ndarray>

// Create a 2x2x2 ndarray:
var y = zeros( [ 2, 2, 2 ] );
// returns <ndarray>

// Broadcast to a common shape:
var out = maybeBroadcastArrays( x, y );
// returns [ <ndarray>, <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 [broadcast-incompatible][@stdlib/ndarray/base/broadcast-shapes] ndarrays.
-   If a provided [ndarray][@stdlib/ndarray/ctor] has a shape matching the common shape, the function returns the provided [ndarray][@stdlib/ndarray/ctor].
-   If a provided [ndarray][@stdlib/ndarray/ctor] has a different (broadcast compatible) shape than the common shape, the function returns a new **read-only** [ndarray][@stdlib/ndarray/ctor] view of the provided [ndarray][@stdlib/ndarray/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 a view may affect multiple elements. If you need to write to an input [ndarray][@stdlib/ndarray/ctor], copy the [ndarray][@stdlib/ndarray/ctor] **before** broadcasting.

</section>

<!-- /.notes -->

<!-- Package usage examples. -->

<section class="examples">

## Examples

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

```javascript
var array = require( '@stdlib/ndarray-array' );
var zeros = require( '@stdlib/ndarray-zeros' );
var numel = require( '@stdlib/ndarray-base-numel' );
var ind2sub = require( '@stdlib/ndarray-ind2sub' );
var maybeBroadcastArrays = require( '@stdlib/ndarray-maybe-broadcast-arrays' );

// Create a 2x2 array:
var x = array( [ [ 1, 2 ], [ 3, 4 ] ] );
// returns <ndarray>

// Create a 3x2x2 array:
var y = zeros( [ 3, 2, 2 ] );
// returns <ndarray>

// Broadcast arrays to a common shape:
var out = maybeBroadcastArrays( [ x, y ] );
// returns <ndarray>

// Retrieve the common shape:
var sh = out[ 0 ].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( 'X[%s] = %d', ind2sub( sh, i ).join( ', ' ), out[ 0 ].iget( i ) );
}
```

</section>

<!-- /.examples -->

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<section class="references">

</section>

<!-- /.references -->

<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. -->

<section class="related">

* * *

## See Also

-   <span class="package-name">[`@stdlib/ndarray-array`][@stdlib/ndarray/array]</span><span class="delimiter">: </span><span class="description">multidimensional arrays.</span>
-   <span class="package-name">[`@stdlib/ndarray-ctor`][@stdlib/ndarray/ctor]</span><span class="delimiter">: </span><span class="description">multidimensional array constructor.</span>
-   <span class="package-name">[`@stdlib/ndarray-broadcast-arrays`][@stdlib/ndarray/broadcast-arrays]</span><span class="delimiter">: </span><span class="description">broadcast ndarrays to a common shape.</span>
-   <span class="package-name">[`@stdlib/ndarray-maybe-broadcast-array`][@stdlib/ndarray/maybe-broadcast-array]</span><span class="delimiter">: </span><span class="description">broadcast an ndarray to a specified shape if and only if the specified shape differs from the provided ndarray's shape.</span>

</section>

<!-- /.related -->

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<section class="main-repo" >

* * *

## 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

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---

## License

See [LICENSE][stdlib-license].


## Copyright

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

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[@stdlib/ndarray/ctor]: https://www.npmjs.com/package/@stdlib/ndarray-ctor

[@stdlib/ndarray/base/broadcast-shapes]: https://www.npmjs.com/package/@stdlib/ndarray-base-broadcast-shapes

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