npm package: @stdlib/ndarray-fill
Description: Fill an input ndarray with a specified value.
Author: The Stdlib Authors
Latest version: 0.1.1

<!--

@license Apache-2.0

Copyright (c) 2025 The Stdlib Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

-->


<details>
  <summary>
    About stdlib...
  </summary>
  <p>We believe in a future in which the web is a preferred environment for numerical computation. To help realize this future, we've built stdlib. stdlib is a standard library, with an emphasis on numerical and scientific computation, written in JavaScript (and C) for execution in browsers and in Node.js.</p>
  <p>The library is fully decomposable, being architected in such a way that you can swap out and mix and match APIs and functionality to cater to your exact preferences and use cases.</p>
  <p>When you use stdlib, you can be absolutely certain that you are using the most thorough, rigorous, well-written, studied, documented, tested, measured, and high-quality code out there.</p>
  <p>To join us in bringing numerical computing to the web, get started by checking us out on <a href="https://github.com/stdlib-js/stdlib">GitHub</a>, and please consider <a href="https://opencollective.com/stdlib">financially supporting stdlib</a>. We greatly appreciate your continued support!</p>
</details>

# fill

[![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url] <!-- [![dependencies][dependencies-image]][dependencies-url] -->

> Fill an input [`ndarray`][@stdlib/ndarray/ctor] with a specified value.

<section class="intro">

</section>

<!-- /.intro -->

<section class="installation">

## Installation

```bash
npm install @stdlib/ndarray-fill
```

</section>

<section class="usage">

## Usage

```javascript
var fill = require( '@stdlib/ndarray-fill' );
```

#### fill( x, value )

Fills an input [`ndarray`][@stdlib/ndarray/ctor] with a specified value.

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

var x = zeros( [ 3, 1, 2 ], {
    'dtype': 'float64'
});

var y = fill( x, 10.0 );
// returns <ndarray>

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

var arr = ndarray2array( x );
// returns [ [ [ 10.0, 10.0 ] ], [ [ 10.0, 10.0 ] ], [ [ 10.0, 10.0 ] ] ]
```

The function accepts the following arguments:

-   **x**: array-like object containing an input [`ndarray`][@stdlib/ndarray/ctor].
-   **value**: scalar value.

</section>

<!-- /.usage -->

<section class="notes">

## Notes

-   An input [`ndarray`][@stdlib/ndarray/ctor] **must** be writable. If provided a **read-only** [`ndarray`][@stdlib/ndarray/ctor], the function throws an error.
-   If `value` is a number and `x` has a complex [data type][@stdlib/ndarray/dtypes], the function fills an input [`ndarray`][@stdlib/ndarray/ctor] with a complex number whose real component equals the provided scalar `value` and whose imaginary component is zero.
-   A `value` must be able to safely cast to the input [`ndarray`][@stdlib/ndarray/ctor] [data type][@stdlib/ndarray/dtypes]. Scalar values having floating-point data types (both real and complex) are allowed to downcast to a lower precision data type of the same kind (e.g., a scalar double-precision floating-point number can be used to fill a `'float32'` input [`ndarray`][@stdlib/ndarray/ctor]).
-   The function **mutates** the input [`ndarray`][@stdlib/ndarray/ctor].

</section>

<!-- /.notes -->

<section class="examples">

## Examples

<!-- eslint no-undef: "error" -->

```javascript
var zeros = require( '@stdlib/ndarray-zeros' );
var ndarray2array = require( '@stdlib/ndarray-to-array' );
var fill = require( '@stdlib/ndarray-fill' );

// Create a zero-filled ndarray:
var x = zeros( [ 5, 2 ], {
    'dtype': 'generic'
});
console.log( ndarray2array( x ) );

// Fill the ndarray with a scalar value:
fill( x, 10.0 );
console.log( ndarray2array( x ) );
```

</section>

<!-- /.examples -->

<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. -->

<section class="related">

* * *

## See Also

-   <span class="package-name">[`@stdlib/ndarray-fill-by`][@stdlib/ndarray/fill-by]</span><span class="delimiter">: </span><span class="description">fill an input ndarray according to a callback function.</span>
-   <span class="package-name">[`@stdlib/ndarray-map`][@stdlib/ndarray/map]</span><span class="delimiter">: </span><span class="description">apply a callback to elements in an input ndarray and assign results to elements in a new output ndarray.</span>
-   <span class="package-name">[`@stdlib/ndarray-zeros`][@stdlib/ndarray/zeros]</span><span class="delimiter">: </span><span class="description">create a zero-filled ndarray having a specified shape and data type.</span>

</section>

<!-- /.related -->


<section class="main-repo" >

* * *

## Notice

This package is part of [stdlib][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][stdlib], see the main project [repository][stdlib].

#### Community

[![Chat][chat-image]][chat-url]

---

## License

See [LICENSE][stdlib-license].


## Copyright

Copyright &copy; 2016-2026. The Stdlib [Authors][stdlib-authors].

</section>

<!-- /.stdlib -->

<!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->

<section class="links">

[npm-image]: http://img.shields.io/npm/v/@stdlib/ndarray-fill.svg
[npm-url]: https://npmjs.org/package/@stdlib/ndarray-fill

[test-image]: https://github.com/stdlib-js/ndarray-fill/actions/workflows/test.yml/badge.svg?branch=v0.1.1
[test-url]: https://github.com/stdlib-js/ndarray-fill/actions/workflows/test.yml?query=branch:v0.1.1

[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/ndarray-fill/main.svg
[coverage-url]: https://codecov.io/github/stdlib-js/ndarray-fill?branch=main

<!--

[dependencies-image]: https://img.shields.io/david/stdlib-js/ndarray-fill.svg
[dependencies-url]: https://david-dm.org/stdlib-js/ndarray-fill/main

-->

[chat-image]: https://img.shields.io/badge/zulip-join_chat-brightgreen.svg
[chat-url]: https://stdlib.zulipchat.com

[stdlib]: https://github.com/stdlib-js/stdlib

[stdlib-authors]: https://github.com/stdlib-js/stdlib/graphs/contributors

[umd]: https://github.com/umdjs/umd
[es-module]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Modules

[deno-url]: https://github.com/stdlib-js/ndarray-fill/tree/deno
[deno-readme]: https://github.com/stdlib-js/ndarray-fill/blob/deno/README.md
[umd-url]: https://github.com/stdlib-js/ndarray-fill/tree/umd
[umd-readme]: https://github.com/stdlib-js/ndarray-fill/blob/umd/README.md
[esm-url]: https://github.com/stdlib-js/ndarray-fill/tree/esm
[esm-readme]: https://github.com/stdlib-js/ndarray-fill/blob/esm/README.md
[branches-url]: https://github.com/stdlib-js/ndarray-fill/blob/main/branches.md

[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/ndarray-fill/main/LICENSE

[@stdlib/ndarray/ctor]: https://www.npmjs.com/package/@stdlib/ndarray-ctor

[@stdlib/ndarray/dtypes]: https://www.npmjs.com/package/@stdlib/ndarray-dtypes

<!-- <related-links> -->

[@stdlib/ndarray/fill-by]: https://www.npmjs.com/package/@stdlib/ndarray-fill-by

[@stdlib/ndarray/map]: https://www.npmjs.com/package/@stdlib/ndarray-map

[@stdlib/ndarray/zeros]: https://www.npmjs.com/package/@stdlib/ndarray-zeros

<!-- </related-links> -->

</section>

<!-- /.links -->