stride
Return the stride along a specified dimension for a provided ndarray.
Usage
var stride = require( '@stdlib/ndarray/stride' );
stride( x, dim )
Returns the stride along a specified dimension for a provided ndarray.
var zeros = require( '@stdlib/ndarray/zeros' );
var x = zeros( [ 3, 2, 3 ] );
// returns <ndarray>
var st = stride( x, 0 );
// returns 6
The function accepts the following arguments:
- x: input ndarray.
- dim: dimension index. If provided an integer less than zero, the dimension index is resolved relative to the last dimension, with the last dimension corresponding to the value
-1.
Notes
- A "stride" is the linear distance (i.e., number of elements) between adjacent elements along a specified dimension.
- This function is intended as a slight performance optimization over
@stdlib/ndarray/strideswhen only a single stride is needed. For retrieving multiple strides, use@stdlib/ndarray/stridesdirectly.
Examples
var zeros = require( '@stdlib/ndarray/zeros' );
var slice = require( '@stdlib/ndarray/slice' );
var E = require( '@stdlib/slice/multi' );
var S = require( '@stdlib/slice/ctor' );
var stride = require( '@stdlib/ndarray/stride' );
// Create an array:
var x = zeros( [ 10, 10, 10, 10 ] );
// returns <ndarray>
// Define some slices:
var slices = [
// :,:,:,:
E( null, null, null, null ),
// 5:10,4,2:4,::-1
E( S( 5, 10 ), 4, S( 2, 4 ), S( null, null, -1 ) ),
// :,:,2,:
E( null, null, 2, null ),
// 1,2,3,:
E( 1, 2, 3, null ),
// 1,3,::2,4::2
E( 1, 3, S( null, null, 2 ), S( 4, null, 2 ) )
];
// Resolve the stride of the first dimension for each slice...
var s;
var i;
for ( i = 0; i < slices.length; i++ ) {
s = slice( x, slices[ i ] );
console.log( '(%s) => %d', s.shape.join( ',' ), stride( s, 0 ) );
}