strides2order

Determine the order of a multidimensional array based on a provided stride array.

Usage

var strides2order = require( '@stdlib/ndarray/base/strides2order' );

strides2order( strides )

Determines the order of a multidimensional array based on a provided stride array.

var order = strides2order( [ 2, 1 ] );
// returns 1

order = strides2order( [ 1, 2 ] );
// returns 2

order = strides2order( [ 3 ] );
// returns 3

order = strides2order( [ 1, 3, 2 ] );
// returns 0

order = strides2order( [] );
// returns 0

The function returns one of the following values:

1: based on the stride array, the array is in row-major order.
2: based on the stride array, the array is in column-major order.
3: based on the stride array, the array is in both row-major and column-major order.
0: based on the stride array, the array is in neither row-major nor column-major order.

Examples

var discreteUniform = require( '@stdlib/random/base/discrete-uniform' );
var shape2strides = require( '@stdlib/ndarray/base/shape2strides' );
var randu = require( '@stdlib/random/base/randu' );
var strides2order = require( '@stdlib/ndarray/base/strides2order' );

var strides;
var order;
var shape;
var i;
var j;

shape = [ 0, 0, 0 ];

for ( i = 0; i < 20; i++ ) {
    // Generate a random array shape:
    shape[ 0 ] = discreteUniform( 1, 10 );
    shape[ 1 ] = discreteUniform( 1, 10 );
    shape[ 2 ] = discreteUniform( 1, 10 );

    // Compute the strides:
    if ( randu() < 0.5 ) {
        strides = shape2strides( shape, 'row-major' );
    } else {
        strides = shape2strides( shape, 'column-major' );
    }
    j = discreteUniform( 0, shape.length-1 );
    strides[ j ] *= ( randu() < 0.5 ) ? -1 : 1;

    // Determine the order:
    order = strides2order( strides );
    console.log( 'Strides: %s. Order: %s.', strides.join( ',' ), order );
}