gsort

Sort a strided array.

Installation

npm install @stdlib/blas-ext-base-gsort

Usage

var gsort = require( '@stdlib/blas-ext-base-gsort' );

gsort( N, order, x, strideX )

Sorts a strided array.

var x = [ 1.0, -2.0, 3.0, -4.0 ];

gsort( x.length, 1.0, x, 1 );
// x => [ -4.0, -2.0, 1.0, 3.0 ]

The function has the following parameters:

• N: number of indexed elements.
• order: sort order. If order < 0.0, the input strided array is sorted in decreasing order. If order > 0.0, the input strided array is sorted in increasing order. If order == 0.0, the input strided array is left unchanged.
• x: input Array or typed array.
• strideX: stride length.

The N and stride parameters determine which elements in the strided array are accessed at runtime. For example, to sort every other element:

var x = [ 1.0, -2.0, 3.0, -4.0 ];

gsort( 2, -1.0, x, 2 );
// x => [ 3.0, -2.0, 1.0, -4.0 ]

Note that indexing is relative to the first index. To introduce an offset, use typed array views.

var Float64Array = require( '@stdlib/array-float64' );

// Initial array...
var x0 = new Float64Array( [ 1.0, 2.0, 3.0, 4.0 ] );

// Create an offset view...
var x1 = new Float64Array( x0.buffer, x0.BYTES_PER_ELEMENT*1 ); // start at 2nd element

// Sort every other element...
gsort( 2, -1.0, x1, 2 );
// x0 => <Float64Array>[ 1.0, 4.0, 3.0, 2.0 ]

gsort.ndarray( N, order, x, strideX, offsetX )

Sorts a strided array using alternative indexing semantics.

var x = [ 1.0, -2.0, 3.0, -4.0 ];

gsort.ndarray( x.length, 1.0, x, 1, 0 );
// x => [ -4.0, -2.0, 1.0, 3.0 ]

The function has the following additional parameters:

• offsetX: starting index.

While typed array views mandate a view offset based on the underlying buffer, the offset parameter supports indexing semantics based on a starting index. For example, to access only the last three elements:

var x = [ 1.0, -2.0, 3.0, -4.0, 5.0, -6.0 ];

gsort.ndarray( 3, 1.0, x, 1, x.length-3 );
// x => [ 1.0, -2.0, 3.0, -6.0, -4.0, 5.0 ]

Notes

• If N <= 0 or order == 0.0, both functions return x unchanged.
• The algorithm distinguishes between -0 and +0. When sorted in increasing order, -0 is sorted before +0. When sorted in decreasing order, -0 is sorted after +0.
• The algorithm sorts NaN values to the end. When sorted in increasing order, NaN values are sorted last. When sorted in decreasing order, NaN values are sorted first.
• The input strided array is sorted in-place (i.e., the input strided array is mutated).

Examples

var discreteUniform = require( '@stdlib/random-array-discrete-uniform' );
var gsort = require( '@stdlib/blas-ext-base-gsort' );

var x = discreteUniform( 10, -100, 100, {
    'dtype': 'generic'
});
console.log( x );

gsort( x.length, -1.0, x, -1 );
console.log( x );

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 © 2016-2026. The Stdlib Authors.