https://github.com/stdlib-js/ndarray-fill-by
Fill an input ndarray according to a callback function.
https://github.com/stdlib-js/ndarray-fill-by
apply array fill for-each foreach javascript map ndarray node node-js nodejs stdlib strided transform unary
Last synced: about 2 months ago
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Fill an input ndarray according to a callback function.
- Host: GitHub
- URL: https://github.com/stdlib-js/ndarray-fill-by
- Owner: stdlib-js
- License: apache-2.0
- Created: 2025-03-23T03:23:30.000Z (about 1 year ago)
- Default Branch: main
- Last Pushed: 2026-04-17T11:17:17.000Z (2 months ago)
- Last Synced: 2026-04-17T12:32:55.038Z (2 months ago)
- Topics: apply, array, fill, for-each, foreach, javascript, map, ndarray, node, node-js, nodejs, stdlib, strided, transform, unary
- Language: JavaScript
- Homepage: https://github.com/stdlib-js/stdlib
- Size: 1.23 MB
- Stars: 0
- Watchers: 2
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- Changelog: CHANGELOG.md
- Contributing: CONTRIBUTING.md
- License: LICENSE
- Code of conduct: CODE_OF_CONDUCT.md
- Citation: CITATION.cff
- Security: SECURITY.md
- Notice: NOTICE
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README
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# fillBy
[![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url]
> Fill an input [ndarray][@stdlib/ndarray/ctor] according to a callback function.
## Installation
```bash
npm install @stdlib/ndarray-fill-by
```
Alternatively,
- To load the package in a website via a `script` tag without installation and bundlers, use the [ES Module][es-module] available on the [`esm`][esm-url] branch (see [README][esm-readme]).
- If you are using Deno, visit the [`deno`][deno-url] branch (see [README][deno-readme] for usage intructions).
- For use in Observable, or in browser/node environments, use the [Universal Module Definition (UMD)][umd] build available on the [`umd`][umd-url] branch (see [README][umd-readme]).
The [branches.md][branches-url] 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
```javascript
var fillBy = require( '@stdlib/ndarray-fill-by' );
```
#### fillBy( x, fcn\[, thisArg] )
Fills an input [ndarray][@stdlib/ndarray/ctor] according to a callback function.
```javascript
var zeros = require( '@stdlib/ndarray-zeros' );
var ndarray2array = require( '@stdlib/ndarray-to-array' );
function fcn( value ) {
return value + 10.0;
}
var x = zeros( [ 3, 1, 2 ], {
'dtype': 'float64'
});
var y = fillBy( x, fcn );
// returns
var bool = ( y === x );
// returns true
var arr = ndarray2array( y );
// 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].
- **fcn**: callback function.
- **thisArg**: callback function execution context (_optional_).
To set the callback function execution context, provide a `thisArg`.
```javascript
var zeros = require( '@stdlib/ndarray-zeros' );
var ndarray2array = require( '@stdlib/ndarray-to-array' );
function fcn( value ) {
return value + this.factor;
}
var x = zeros( [ 3, 1, 2 ], {
'dtype': 'float64'
});
var ctx = {
'factor': 10.0
};
var y = fillBy( x, fcn, ctx );
// returns
var arr = ndarray2array( y );
// returns [ [ [ 10.0, 10.0 ] ], [ [ 10.0, 10.0 ] ], [ [ 10.0, 10.0 ] ] ]
```
The callback function is provided the following arguments:
- **value**: current array element.
- **indices**: current array element indices.
- **arr**: the input [ndarray][@stdlib/ndarray/ctor].
## Notes
- An input [ndarray][@stdlib/ndarray/ctor] **must** be writable. If provided a **read-only** [ndarray][@stdlib/ndarray/ctor], the function throws an error.
- The function **mutates** the input [ndarray][@stdlib/ndarray/ctor].
- The function assumes that each element in the underlying input [ndarray][@stdlib/ndarray/ctor] data buffer has one, and only one, corresponding element in input [ndarray][@stdlib/ndarray/ctor] view (i.e., a provided [ndarray][@stdlib/ndarray/ctor] is not a broadcasted [ndarray][@stdlib/ndarray/ctor] view).
## Examples
```javascript
var discreteUniform = require( '@stdlib/random-base-discrete-uniform' ).factory;
var ndarray2array = require( '@stdlib/ndarray-to-array' );
var zeros = require( '@stdlib/ndarray-zeros' );
var fillBy = require( '@stdlib/ndarray-fill-by' );
// Create a zero-filled ndarray:
var x = zeros( [ 5, 2 ], {
'dtype': 'generic'
});
console.log( ndarray2array( x ) );
// Fill the ndarray with random values:
fillBy( x, discreteUniform( -100, 100 ) );
console.log( ndarray2array( x ) );
```
* * *
## See Also
- [`@stdlib/ndarray-fill`][@stdlib/ndarray/fill]: fill an input ndarray with a specified value.
- [`@stdlib/ndarray-map`][@stdlib/ndarray/map]: apply a callback to elements in an input ndarray and assign results to elements in a new output ndarray.
- [`@stdlib/ndarray-zeros`][@stdlib/ndarray/zeros]: create a zero-filled ndarray having a specified shape and data type.
* * *
## 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 © 2016-2026. The Stdlib [Authors][stdlib-authors].
[npm-image]: http://img.shields.io/npm/v/@stdlib/ndarray-fill-by.svg
[npm-url]: https://npmjs.org/package/@stdlib/ndarray-fill-by
[test-image]: https://github.com/stdlib-js/ndarray-fill-by/actions/workflows/test.yml/badge.svg?branch=main
[test-url]: https://github.com/stdlib-js/ndarray-fill-by/actions/workflows/test.yml?query=branch:main
[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/ndarray-fill-by/main.svg
[coverage-url]: https://codecov.io/github/stdlib-js/ndarray-fill-by?branch=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-by/tree/deno
[deno-readme]: https://github.com/stdlib-js/ndarray-fill-by/blob/deno/README.md
[umd-url]: https://github.com/stdlib-js/ndarray-fill-by/tree/umd
[umd-readme]: https://github.com/stdlib-js/ndarray-fill-by/blob/umd/README.md
[esm-url]: https://github.com/stdlib-js/ndarray-fill-by/tree/esm
[esm-readme]: https://github.com/stdlib-js/ndarray-fill-by/blob/esm/README.md
[branches-url]: https://github.com/stdlib-js/ndarray-fill-by/blob/main/branches.md
[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/ndarray-fill-by/main/LICENSE
[@stdlib/ndarray/ctor]: https://github.com/stdlib-js/ndarray-ctor
[@stdlib/ndarray/fill]: https://github.com/stdlib-js/ndarray-fill
[@stdlib/ndarray/map]: https://github.com/stdlib-js/ndarray-map
[@stdlib/ndarray/zeros]: https://github.com/stdlib-js/ndarray-zeros