maybeBroadcastArrays

Broadcast ndarrays to a common shape.

Installation

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

Usage

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

maybeBroadcastArrays( arrays )

Broadcasts ndarrays to a common shape.

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 arguments:

1. providing a single array of ndarray arguments.
2. providing ndarray arguments as separate arguments.

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> ]

Notes

• The function throws an error if a provided broadcast-incompatible ndarrays.
• If a provided ndarray has a shape matching the common shape, the function returns the provided ndarray.
• If a provided ndarray has a different (broadcast compatible) shape than the common shape, the function returns a new read-only ndarray view of the provided ndarray'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, copy the ndarray before broadcasting.

Examples

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 ) );
}

See Also

• @stdlib/ndarray-array: multidimensional arrays.
• @stdlib/ndarray-ctor: multidimensional array constructor.
• @stdlib/ndarray-broadcast-arrays: broadcast ndarrays to a common shape.
• @stdlib/ndarray-maybe-broadcast-array: broadcast an ndarray to a specified shape if and only if the specified shape differs from the provided ndarray's shape.

Notice

This package is part of 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, see the main project repository.

Community

License

See LICENSE.

Copyright

Copyright © 2016-2024. The Stdlib Authors.