reverseDimension

Return a view of an input ndarray in which the order of elements along a specified dimension is reversed.

Installation

npm install @stdlib/ndarray-base-reverse-dimension

Usage

var reverseDimension = require( '@stdlib/ndarray-base-reverse-dimension' );

reverseDimension( x, dim, writable )

Returns a view of an input ndarray in which the order of elements along a specified dimension is reversed.

var ndarray = require( '@stdlib/ndarray-ctor' );
var ndarray2array = require( '@stdlib/ndarray-to-array' );

var buffer = [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ];
var shape = [ 3, 2 ];
var strides = [ 2, 1 ];
var offset = 0;

var x = ndarray( 'generic', buffer, shape, strides, offset, 'row-major' );
// returns <ndarray>

var sh = x.shape;
// returns [ 3, 2 ]

var arr = ndarray2array( x );
// returns [ [ 1.0, 2.0 ], [ 3.0, 4.0 ], [ 5.0, 6.0 ] ]

var y = reverseDimension( x, 0, false );
// returns <ndarray>

sh = y.shape;
// returns [ 3, 2 ]

arr = ndarray2array( y );
// returns [ [ 5.0, 6.0 ], [ 3.0, 4.0 ], [ 1.0, 2.0 ] ]

The function accepts the following arguments:

• x: input ndarray.
• dim: index of dimension along which to reverse elements. 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.
• writable: boolean indicating whether a returned ndarray should be writable.

Notes

• The writable parameter only applies to ndarray constructors supporting read-only instances.

Examples

var array = require( '@stdlib/ndarray-array' );
var ndarray2array = require( '@stdlib/ndarray-to-array' );
var zeroTo = require( '@stdlib/array-base-zero-to' );
var reverseDimension = require( '@stdlib/ndarray-base-reverse-dimension' );

// Create a linear ndarray buffer:
var buf = zeroTo( 16 );

// Create a three-dimensional ndarray:
var x = array( buf, {
    'shape': [ 2, 4, 2 ]
});

// Reverse the order of first axis:
var y0 = reverseDimension( x, 0, false );
// returns <ndarray>

var a0 = ndarray2array( y0 );
// returns [ [ [ 8, 9 ], [ 10, 11 ], [ 12, 13 ], [ 14, 15 ] ], [ [ 0, 1 ], [ 2, 3 ], [ 4, 5 ], [ 6, 7 ] ] ]

// Reverse the order of second axis:
var y1 = reverseDimension( x, 1, false );
// returns <ndarray>

var a1 = ndarray2array( y1 );
// returns [ [ [ 6, 7 ], [ 4, 5 ], [ 2, 3 ], [ 0, 1 ] ], [ [ 14, 15 ], [ 12, 13 ], [ 10, 11 ], [ 8, 9 ] ] ]

// Reverse the order of third axis:
var y2 = reverseDimension( x, 2, false );
// returns <ndarray>

var a2 = ndarray2array( y2 );
// returns [ [ [ 1, 0 ], [ 3, 2 ], [ 5, 4 ], [ 7, 6 ] ], [ [ 9, 8 ], [ 11, 10 ], [ 13, 12 ], [ 15, 14 ] ] ]

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.