@stdlib/ndarray-base-shape2strides NPM

shape2strides

Generate a stride array from an array shape.

Installation

npm install @stdlib/ndarray-base-shape2strides

Usage

var shape2strides = require( '@stdlib/ndarray-base-shape2strides' );

shape2strides( shape, order )

Generates a stride array from an array shape.

var strides = shape2strides( [ 3, 2 ], 'row-major' );
// returns [ 2, 1 ]

The order parameter specifies whether an array is row-major (C-style) or column-major (Fortran-style).

var strides = shape2strides( [ 3, 2 ], 'column-major' );
// returns [ 1, 3 ]

shape2strides.assign( shape, order, out )

Generates a stride array from an array shape and assigns results to a provided output array.

var shape = [ 3, 2 ];
var strides = [ 0, 0 ];

var out = shape2strides.assign( shape, 'row-major', strides );
// returns [ 2, 1 ]

var bool = ( strides === out );
// returns true

Examples

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

var strides;
var shape;
var i;

shape = [ 0, 0, 0 ];
for ( i = 0; i < 100; i++ ) {
    shape[ 0 ] = discreteUniform( 1, 10 );
    shape[ 1 ] = discreteUniform( 1, 10 );
    shape[ 2 ] = discreteUniform( 1, 10 );
    strides = shape2strides( shape, 'row-major' );
    console.log( 'shape: %s. strides: %s.', shape.join( 'x' ), strides.join( ', ' ) );
}

C APIs

Usage

#include "stdlib/ndarray/base/shape2strides.h"

stdlib_ndarray_shape2strides( ndims, shape, order, out )

Generates a stride array from an array shape.

#include "stdlib/ndarray/orders.h"

int64_t ndims = 3;
int64_t shape[] = { 2, 3, 10 };
int64_t out[ 3 ];

stdlib_ndarray_shape2strides( ndims, shape, STDLIB_NDARRAY_ROW_MAJOR, out );

The function accepts the following arguments:

ndims: [in] int64_t number of dimensions.
shape: [in] int64_t* array shape (dimensions).
order: [in] enum STDLIB_NDARRAY_ORDER specifies whether an array is row-major (C-style) or column-major (Fortran-style).
out: [out] int64_t* output strides array.

int8_t stdlib_ndarray_shape2strides( int64_t ndims, int64_t *shape, enum STDLIB_NDARRAY_ORDER order, int64_t *out );

Examples

#include "stdlib/ndarray/base/shape2strides.h"
#include "stdlib/ndarray/orders.h"
#include <stdio.h>
#include <inttypes.h>

int main( void ) {
    int64_t shape[] = { 2, 3, 10 };
    int64_t ndims = 3;
    int64_t out[ 3 ];

    stdlib_ndarray_shape2strides( ndims, shape, STDLIB_NDARRAY_ROW_MAJOR, out );

    int i;
    printf( "strides = { " );
    for ( i = 0; i < ndims; i++ ) {
        printf( "%"PRId64"", out[ i ] );
        if ( i < ndims-1 ) {
            printf( ", " );
        }
    }
    printf( " }\n" );
}

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.