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copyWithin

Perform an in-place copy of elements within an ndarray along an ndarray dimension.

Installation

npm install @stdlib/blas-ext-copy-within

Alternatively,

• To load the package in a website via a script tag without installation and bundlers, use the ES Module available on the esm branch (see README).
• If you are using Deno, visit the deno branch (see README for usage intructions).
• For use in Observable, or in browser/node environments, use the Universal Module Definition (UMD) build available on the umd branch (see README).

The branches.md file summarizes the available branches and displays a diagram illustrating their relationships.

To view installation and usage instructions specific to each branch build, be sure to explicitly navigate to the respective README files on each branch, as linked to above.

Usage

var copyWithin = require( '@stdlib/blas-ext-copy-within' );

copyWithin( x, target, start[, end][, options] )

Performs an in-place copy of elements within an ndarray along an ndarray dimension.

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

// Create an input ndarray:
var x = array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ] );
// returns <ndarray>[ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ]

// Perform operation:
var y = copyWithin( x, 3, 1, 4 );
// returns <ndarray>[ 1.0, 2.0, 3.0, 2.0, 3.0, 4.0 ]

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

The function has the following parameters:

• x: input ndarray.
• target: target index. May be either an integer or an ndarray having an integer index 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.dim. For example, given the input shape [2, 3, 4] and options.dim=0, an ndarray target index must have a shape which is broadcast-compatible with the shape [3, 4].
• start: source start index (inclusive). May be either an integer or an ndarray having an integer index or "generic" data type and following the same broadcasting semantics as the target argument.
• end: source end index (exclusive) (optional). May be either an integer or an ndarray having an integer index or "generic" data type and following the same broadcasting semantics as the target argument. By default, the source end index is N, where N is the number of elements along the dimension specified by options.dim.
• options: function options (optional).

The function accepts the following options:

• dim: dimension over which to perform operation. If provided a negative integer, the dimension along which to perform the operation is determined by counting backward from the last dimension (where -1 refers to the last dimension). Default: -1.

When a target, start, and/or end index is negative, the respective index is determined relative to the last indexed element, with out-of-bounds indices clamped to index bounds.

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

var x = array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ] );

var y = copyWithin( x, 0, -2 );
// returns <ndarray>[ 5.0, 6.0, 3.0, 4.0, 5.0, 6.0 ]

By default, the function performs the operation over elements along the last dimension. To perform the operation over a different dimension, provide a dim option.

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

var x = array( [ [ 1.0, 2.0, 3.0, 4.0 ], [ 5.0, 6.0, 7.0, 8.0 ] ] );

var y = copyWithin( x, 1, 0, {
    'dim': 0
});
// returns <ndarray>[ [ 1.0, 2.0, 3.0, 4.0 ], [ 1.0, 2.0, 3.0, 4.0 ] ]

Notes

• The input ndarray is copied in-place (i.e., the input ndarray is mutated).

Examples

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

// Generate an ndarray of random numbers:
var x = discreteUniform( [ 5, 5 ], 0, 20, {
    'dtype': 'generic'
});
console.log( ndarray2array( x ) );

// Perform operation:
copyWithin( x, -2, 0, 2, {
    'dim': 0
});

// Print the results:
console.log( ndarray2array( 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 © 2016-2026. The Stdlib Authors.