@stdlib/strided-base-nullary

Nullary

Apply a nullary callback and assign results to elements in a strided output array.

Installation

npm install @stdlib/strided-base-nullary

Usage

var nullary = require( '@stdlib/strided-base-nullary' );

nullary( arrays, shape, strides, fcn )

Applies a nullary callback and assigns results to elements in a strided output array.

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

function fill() {
    return 3.0;
}

var x = new Float64Array( [ -2.0, 1.0, 3.0, -5.0, 4.0, 0.0, -1.0, -3.0 ] );

nullary( [ x ], [ x.length ], [ 1 ], fill );
// x => <Float64Array>[ 3.0, 3.0, 3.0, 3.0, 3.0, 3.0, 3.0, 3.0 ]

The function accepts the following arguments:

• arrays: array-like object containing one strided output array.
• shape: array-like object containing a single element, the number of indexed elements.
• strides: array-like object containing the stride length for the strided output array.
• fcn: nullary function to apply.

The shape and strides parameters determine which elements in the strided output array are accessed at runtime. For example, to index the first N elements of the strided output array in reverse order,

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

function fill() {
    return 3.0;
}

var x = new Float64Array( [ -1.0, -2.0, -3.0, -4.0, -5.0, -6.0 ] );

nullary( [ x ], [ 3 ], [ -1 ], fill );
// x => <Float64Array>[ 3.0, 3.0, 3.0, -4.0, -5.0, -6.0 ]

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

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

function fill() {
    return 3.0;
}

// Initial arrays...
var x0 = new Float64Array( [ -1.0, -2.0, -3.0, -4.0, -5.0, -6.0 ] );

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

nullary( [ x1 ], [ 3 ], [ 1 ], fill );
// x0 => <Float64Array>[ -1.0, 3.0, 3.0, 3.0, -5.0, -6.0 ]

nullary.ndarray( arrays, shape, strides, offsets, fcn )

Applies a nullary callback and assigns results to elements in a strided output array using alternative indexing semantics.

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

function fill() {
    return 3.0;
}

var x = new Float64Array( [ -1.0, -2.0, -3.0, -4.0, -5.0 ] );

nullary.ndarray( [ x ], [ x.length ], [ 1 ], [ 0 ], fill );
// x => <Float64Array>[ 3.0, 3.0, 3.0, 3.0, 3.0 ]

The function accepts the following additional arguments:

• offsets: array-like object containing the starting index (i.e., index offset) for the strided output array.

While typed array views mandate a view offset based on the underlying buffer, the offsets parameter supports indexing semantics based on starting indices. For example, to index the last N elements in the strided output array,

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

function fill() {
    return 3.0;
}

var x = new Float64Array( [ -1.0, -2.0, -3.0, -4.0, -5.0, -6.0 ] );

nullary.ndarray( [ x ], [ 3 ], [ -1 ], [ x.length-1 ], fill );
// x => <Float64Array>[ -1.0, -2.0, -3.0, 3.0, 3.0, 3.0 ]

Examples

var discreteUniform = require( '@stdlib/random-base-discrete-uniform' ).factory;
var filledarray = require( '@stdlib/array-filled' );
var nullary = require( '@stdlib/strided-base-nullary' );

var x = filledarray( 0.0, 10, 'generic' );
console.log( x );

var shape = [ x.length ];
var strides = [ 1 ];
var offsets = [ 0 ];

nullary.ndarray( [ x ], shape, strides, offsets, discreteUniform( -100, 100 ) );
console.log( x );

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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

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License

See LICENSE.

Copyright

Copyright © 2016-2022. The Stdlib Authors.