sorthp

Sort an input ndarray along one or more ndarray dimensions using heapsort.

Installation

npm install @stdlib/blas-ext-sorthp

Usage

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

sorthp( x[, sortOrder][, options] )

Sorts an input ndarray along one or more ndarray dimensions using heapsort.

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

var x = array( [ -1.0, 2.0, -3.0 ] );

var y = sorthp( x );
// returns <ndarray>

var arr = ndarray2array( y );
// returns [ -3.0, -1.0, 2.0 ]

var bool = ( x === y );
// returns true

The function has the following parameters:

• x: input ndarray. Must have a real-valued or "generic" data type.
• sortOrder: sort order (optional). May be either a scalar value, string, or an ndarray having a real-valued or "generic" data type. If provided an ndarray, the value must have a shape which is broadcast-compatible with the complement of the shape defined by options.dims. For example, given the input shape [2, 3, 4] and options.dims=[0], an ndarray sort order must have a shape which is broadcast-compatible with the shape [3, 4]. Similarly, when performing the operation over all elements in a provided input ndarray, an ndarray sort order must be a zero-dimensional ndarray. By default, the sort order is 1 (i.e., increasing order).
• options: function options (optional).

The function accepts the following options:

• dims: list of dimensions over which to perform operation. If not provided, the function performs the operation over all elements in a provided input ndarray.

By default, the function sorts elements in increasing order. To sort in a different order, provide a sortOrder argument.

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

var x = array( [ -1.0, 2.0, -3.0 ] );

var y = sorthp( x, -1.0 );
// returns <ndarray>

var arr = ndarray2array( y );
// returns [ 2.0, -1.0, -3.0 ]

In addition to numeric values, one can specify the sort order via one of the following string literals: 'ascending', 'asc', 'descending', or 'desc'. The first two literals indicate to sort in ascending (i.e., increasing) order. The last two literals indicate to sort in descending (i.e., decreasing) order.

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

var x = array( [ -1.0, 2.0, -3.0 ] );

// Sort in ascending order:
var y = sorthp( x, 'asc' );
// returns <ndarray>

var arr = ndarray2array( y );
// returns [ -3.0, -1.0, 2.0 ]

// Sort in descending order:
y = sorthp( x, 'descending' );
// returns <ndarray>

arr = ndarray2array( y );
// returns [ 2.0, -1.0, -3.0 ]

By default, the function performs the operation over all elements in a provided input ndarray. To perform the operation over specific dimensions, provide a dims option.

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

var x = array( [ -1.0, 2.0, -3.0, 4.0 ], {
    'shape': [ 2, 2 ],
    'order': 'row-major'
});

var v = ndarray2array( x );
// returns [ [ -1.0, 2.0 ], [ -3.0, 4.0 ] ]

var y = sorthp( x, {
    'dims': [ 0 ]
});
// returns <ndarray>

v = ndarray2array( y );
// returns [ [ -3.0, 2.0 ], [ -1.0, 4.0 ] ]

Notes

• The input ndarray is sorted in-place (i.e., the input ndarray is mutated).
• If sortOrder < 0.0 or is either 'desc' or 'descending', the input ndarray is sorted in decreasing order. If sortOrder > 0.0 or is either 'asc' or 'ascending', the input ndarray is sorted in increasing order. If sortOrder == 0.0, the input ndarray is left 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 algorithm has space complexity O(1) and time complexity O(N log2 N).
• The algorithm is unstable, meaning that the algorithm may change the order of ndarray elements which are equal or equivalent (e.g., NaN values).
• The function iterates over ndarray elements according to the memory layout of the input ndarray. Accordingly, performance degradation is possible when operating over multiple dimensions of a large non-contiguous multi-dimensional input ndarray. In such scenarios, one may want to copy an input ndarray to contiguous memory before sorting.

Examples

var discreteUniform = require( '@stdlib/random-array-discrete-uniform' );
var ndarray2array = require( '@stdlib/ndarray-to-array' );
var ndarray = require( '@stdlib/ndarray-ctor' );
var sorthp = require( '@stdlib/blas-ext-sorthp' );

// Generate an array of random numbers:
var xbuf = discreteUniform( 25, -20, 20, {
    'dtype': 'generic'
});

// Wrap in an ndarray:
var x = new ndarray( 'generic', xbuf, [ 5, 5 ], [ 5, 1 ], 0, 'row-major' );
console.log( ndarray2array( x ) );

// Perform operation:
sorthp( x, {
    'dims': [ 0 ]
});

// Print the results:
console.log( ndarray2array( 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.