Iteration Order

Given a stride array, determine array iteration order.

Installation

npm install @stdlib/ndarray-base-iteration-order

Usage

var iterationOrder = require( '@stdlib/ndarray-base-iteration-order' );

iterationOrder( strides )

Returns the array iteration order.

var o = iterationOrder( [ 2, 1 ] );
// returns 1

o = iterationOrder( [ -2, 1 ] );
// returns 0

o = iterationOrder( [ -2, -1 ] );
// returns -1

The function returns one of the following values:

• 0: unordered (strides are of mixed sign).
• 1: left-to-right iteration order (strides are all nonnegative).
• -1: right-to-left iteration order (strides are all negative).

Examples

var discreteUniform = require( '@stdlib/random-base-discrete-uniform' );
var shape2strides = require( '@stdlib/ndarray-base-shape2strides' );
var randu = require( '@stdlib/random-base-randu' );
var iterationOrder = require( '@stdlib/ndarray-base-iteration-order' );

var strides;
var shape;
var out;
var i;
var j;

shape = [ 0, 0, 0 ];
shape[ 0 ] = discreteUniform( 1, 10 );
shape[ 1 ] = discreteUniform( 1, 10 );
shape[ 2 ] = discreteUniform( 1, 10 );

strides = shape2strides( shape, 'row-major' );

for ( i = 0; i < 100; i++ ) {
    j = discreteUniform( 0, shape.length-1 );
    strides[ j ] *= ( randu() < 0.5 ) ? -1 : 1;
    out = iterationOrder( strides );
    console.log( 'strides: %s => %d', strides.join( ',' ), out );
}

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.