@stdlib/ndarray-broadcast-arrays NPM

broadcastArrays

Broadcast ndarrays to a common shape.

Installation

npm install @stdlib/ndarray-broadcast-arrays

Usage

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

broadcastArrays( ...arrays )

Broadcasts a list of 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 = broadcastArrays( [ x, y ] );
// returns [ <ndarray>, <ndarray> ]

The function supports two (mutually exclusive) means for providing ndarray arguments:

providing a single array of ndarray arguments.
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 = broadcastArrays( x, y );
// returns [ <ndarray>, <ndarray> ]

Notes

The function throws an error if provided broadcast-incompatible ndarrays.
Returned ndarrays are read-only views on their respective underlying data buffers. The views are 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 a returned ndarray, copy the ndarray before broadcasting.
The function always returns new ndarray instances even if an input ndarray shape and the broadcasted shape are the same.

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 broadcastArrays = require( '@stdlib/ndarray-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 the arrays to a common shape:
var out = broadcastArrays( [ x, y ] );
// returns [ <ndarray>, <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 ) );
}

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.