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Replace specified elements of an array with provided values.

npm install @stdlib/array-put

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.

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

Replaces specified elements of an array with provided values.

var x = [ 1, 2, 3, 4 ];

var out = put( x, [ 1, 3 ], [ 20, 40 ] );
// returns [ 1, 20, 3, 40 ]

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

The function supports the following parameters:

• x: input array.
• indices: list of indices.
• values: values to set. When indices contains one or more elements, values must be broadcast compatible with indices (i.e., must have either one element or the same number of elements as indices).
• options: function options.

The function supports the following options:

• mode: index mode. Default: 'normalize'.

If indices is an empty array, the function returns the input array unchanged.

var x = [ 1, 2, 3, 4 ];

var out = put( x, [], [ 20, 40 ] );
// returns [ 1, 2, 3, 4 ]

The function supports broadcasting a values array containing a single element against an indices array containing one or more elements.

var x = [ 1, 2, 3, 4 ];

var out = put( x, [ 1, 3 ], [ 20 ] );
// returns [ 1, 20, 3, 20 ]

By default, the function normalizes negative integer indices to positive integer index equivalents.

var x = [ 1, 2, 3, 4 ];

var out = put( x, [ -3, -1 ], [ 20, 40 ] );
// returns [ 1, 20, 3, 40 ]

To specify an alternative index mode, provide a mode option.

var x = [ 1, 2, 3, 4 ];

var out = put( x, [ -10, 10 ], [ 20, 40 ], {
    'mode': 'clamp'
});
// returns [ 20, 2, 3, 40 ]

• The function mutates the input array x.
• Because each index is only validated at the time of replacing a particular element, mutation may occur even when one or more indices are out-of-bounds, including when the index mode indicates to raise an exception.
• The values array must have a data type which can be safely cast to the input array data type. Floating-point data types (both real and complex) are allowed to downcast to a lower precision data type of the same kind (e.g., element values from a 'float64' values array can be assigned to corresponding elements in a 'float32' input array).

var filledBy = require( '@stdlib/array-base-filled-by' );
var discreteUniform = require( '@stdlib/random-base-discrete-uniform' );
var linspace = require( '@stdlib/array-base-linspace' );
var put = require( '@stdlib/array-put' );

// Generate a linearly spaced array:
var x = linspace( 0, 100, 11 );
console.log( x );

// Generate an array of random indices:
var N = discreteUniform( 5, 15 );
var indices = filledBy( N, discreteUniform.factory( 0, x.length-1 ) );
console.log( indices );

// Generate an array of random values:
var values = filledBy( N, discreteUniform.factory( 1000, 2000 ) );
console.log( values );

// Update a random sample of elements in `x`:
var out = put( x, indices, values );
console.log( out );

• @stdlib/array-mskput: replace elements of an array with provided values according to a provided mask array.
• @stdlib/array-place: replace elements of an array with provided values according to a provided mask array.
• @stdlib/array-take: take elements from an array.

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.

See LICENSE.

Copyright © 2016-2026. The Stdlib Authors.