npm package: @stdlib/array-base-broadcast-array
Description: Broadcast an array to a specified shape.
Author: The Stdlib Authors
Latest version: 0.2.3

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# broadcastArray

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> Broadcast an array to a specified shape.

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<section class="intro">

</section>

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<!-- Package usage documentation. -->

<section class="installation">

## Installation

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

</section>

<section class="usage">

## Usage

```javascript
var broadcastArray = require( '@stdlib/array-base-broadcast-array' );
```

#### broadcastArray( x, inShape, outShape )

Broadcasts an array to a specified shape.

```javascript
var x = [ 1, 2 ];

var out = broadcastArray( x, [ 2 ], [ 2, 2 ] );
// returns {...}

var shape = out.shape;
// returns [ 2, 2 ]

var strides = out.strides;
// returns [ 0, 1 ]

var ref = out.ref;
// returns [ 1, 2 ]

var bool = ( x === ref );
// returns true

var data = out.data;
// returns [ [ 1, 2 ] ]
```

The function returns an object having the following properties:

-   **ref**: reference to the original input array.
-   **data**: broadcasted array.
-   **shape**: broadcasted array shape.
-   **strides**: broadcasted array strides. Strides describe how to iterate over broadcasted array dimensions.

</section>

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<!-- 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 broadcasted array shares the same data as the input array. As more than one element of a broadcasted array may refer to the same memory location, writing to the broadcasted array may affect multiple elements. If you need to write to the broadcasted array, copy the array **before** performing operations which may mutate elements.
-   The function throws an error if a provided input shape is [incompatible][@stdlib/ndarray/base/broadcast-shapes] with a provided output shape.

</section>

<!-- /.notes -->

<!-- Package usage examples. -->

<section class="examples">

## Examples

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

```javascript
var broadcastArray = require( '@stdlib/array-base-broadcast-array' );

// Create a 2x1 array:
var x = [
    [ 1 ],
    [ 2 ]
];

// Broadcast the array to 3x2x4:
var o = broadcastArray( x, [ 2, 1 ], [ 3, 2, 4 ] );
// returns {...}

// Retrieve the shape:
var sh = o.shape;
// returns [ 3, 2, 4 ]

// Retrieve the array "strides":
var st = o.strides;
// returns [...]

// Initialize loop indices:
var i0 = 0;
var i1 = 0;
var i2 = 0;

// Iterate over elements in the broadcasted array...
var i;
var j;
var k;
for ( i = 0; i < sh[ 0 ]; i++ ) {
    i1 = 0;
    for ( j = 0; j < sh[ 1 ]; j++ ) {
        i2 = 0;
        for ( k = 0; k < sh[ 2 ]; k++ ) {
            console.log( 'y[%s] = %d', [ i, j, k ].join( ',' ), o.data[ i0 ][ i1 ][ i2 ] );
            i2 += st[ 2 ];
        }
        i1 += st[ 1 ];
    }
    i0 += st[ 0 ];
}
```

</section>

<!-- /.examples -->

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

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