https://github.com/stdlib-js/ndarray-slice-assign

Assign element values from a broadcasted input ndarray to corresponding elements in an output ndarray view.
https://github.com/stdlib-js/ndarray-slice-assign
assign assignment copy data javascript matrix ndarray node node-js nodejs set setitem slice stdlib structure types vector view
Last synced: about 1 year ago
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Assign element values from a broadcasted input ndarray to corresponding elements in an output ndarray view.
Host: GitHub
URL: https://github.com/stdlib-js/ndarray-slice-assign
Owner: stdlib-js
License: apache-2.0
Created: 2023-09-30T09:54:20.000Z (over 2 years ago)
Default Branch: main
Last Pushed: 2025-04-07T01:19:07.000Z (about 1 year ago)
Last Synced: 2025-04-07T01:31:58.913Z (about 1 year ago)
Topics: assign, assignment, copy, data, javascript, matrix, ndarray, node, node-js, nodejs, set, setitem, slice, stdlib, structure, types, vector, view
Language: JavaScript
Homepage: https://github.com/stdlib-js/stdlib
Size: 2.68 MB
Stars: 1
Watchers: 3
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
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# sliceAssign

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

> Assign element values from a broadcasted input [`ndarray`][@stdlib/ndarray/ctor] to corresponding elements in an output [`ndarray`][@stdlib/ndarray/ctor] view.

## Installation

```bash

npm install @stdlib/ndarray-slice-assign

```

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 sliceAssign = require( '@stdlib/ndarray-slice-assign' );

```

#### sliceAssign( x, y, ...s\[, options] )

Assigns element values from a broadcasted input [`ndarray`][@stdlib/ndarray/ctor] to corresponding elements in an output [`ndarray`][@stdlib/ndarray/ctor] view.

```javascript

var Slice = require( '@stdlib/slice-ctor' );

var MultiSlice = require( '@stdlib/slice-multi' );

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

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

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

// Define an input array:

var buffer = [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0 ];

var shape = [ 3, 2 ];

var strides = [ 2, 1 ];

var offset = 0;

var x = ndarray( 'generic', buffer, shape, strides, offset, 'row-major' );

// returns 

var sh = x.shape;

// returns [ 3, 2 ]

var arr = ndarray2array( x );

// returns [ [ 1.0, 2.0 ], [ 3.0, 4.0 ], [ 5.0, 6.0 ] ]

// Define an output array:

var y = ndzeros( [ 2, 3, 2 ], {

    'dtype': x.dtype

});

// Create a slice:

var s0 = null;

var s1 = new Slice( null, null, -1 );

var s2 = new Slice( null, null, -1 );

var s = new MultiSlice( s0, s1, s2 );

// returns 

// Perform assignment:

var out = sliceAssign( x, y, s );

// returns 

var bool = ( out === y );

// returns true

arr = ndarray2array( y );

// returns [ [ [ 6.0, 5.0 ], [ 4.0, 3.0 ], [ 2.0, 1.0 ] ], [ [ 6.0, 5.0 ], [ 4.0, 3.0 ], [ 2.0, 1.0 ] ] ]

```

The function accepts the following arguments:

-   **x**: input [`ndarray`][@stdlib/ndarray/ctor].

-   **y**: output [`ndarray`][@stdlib/ndarray/ctor].

-   **s**: a [`MultiSlice`][@stdlib/slice/multi] instance, an array of slice arguments, or slice arguments as separate arguments.

-   **options**: function options.

The function supports three (mutually exclusive) means for providing slice arguments:

1.  providing a single [`MultiSlice`][@stdlib/slice/multi] instance.

2.  providing a single array of slice arguments.

3.  providing slice arguments as separate arguments.

The following example demonstrates each invocation style achieving equivalent results.

```javascript

var Slice = require( '@stdlib/slice-ctor' );

var MultiSlice = require( '@stdlib/slice-multi' );

var scalar2ndarray = require( '@stdlib/ndarray-from-scalar' );

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

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

// 1. Using a MultiSlice:

var x = scalar2ndarray( 10.0 );

var y = ndzeros( [ 2, 3 ] );

var s0 = 0;

var s1 = new Slice( 1, null, 1 );

var s = new MultiSlice( s0, s1 );

// returns 

var out = sliceAssign( x, y, s );

// returns 

var arr = ndarray2array( out );

// returns [ [ 0.0, 10.0, 10.0 ], [ 0.0, 0.0, 0.0 ] ]

// 2. Using an array of slice arguments:

x = scalar2ndarray( 10.0 );

y = ndzeros( [ 2, 3 ] );

out = sliceAssign( x, y, [ s0, s1 ] );

// returns 

arr = ndarray2array( out );

// returns [ [ 0.0, 10.0, 10.0 ], [ 0.0, 0.0, 0.0 ] ]

// 3. Providing separate arguments:

x = scalar2ndarray( 10.0 );

y = ndzeros( [ 2, 3 ] );

out = sliceAssign( x, y, s0, s1 );

// returns 

arr = ndarray2array( out );

// returns [ [ 0.0, 10.0, 10.0 ], [ 0.0, 0.0, 0.0 ] ]

```

The function supports the following `options`:

-   **strict**: boolean indicating whether to enforce strict bounds checking.

By default, the function throws an error when provided a slice which exceeds array bounds. To ignore slice indices exceeding array bounds, set the `strict` option to `false`.

```javascript

var Slice = require( '@stdlib/slice-ctor' );

var MultiSlice = require( '@stdlib/slice-multi' );

var scalar2ndarray = require( '@stdlib/ndarray-from-scalar' );

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

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

// Define an input array:

var x = scalar2ndarray( 10.0 );

// Define an output array:

var y = ndzeros( [ 3, 2 ], {

    'dtype': x.dtype

});

// Create a slice:

var s0 = new Slice( 1, null, 1 );

var s1 = new Slice( 10, 20, 1 );

var s = new MultiSlice( s0, s1 );

// returns 

// Perform assignment:

var out = sliceAssign( x, y, s, {

    'strict': false

});

// returns 

var arr = ndarray2array( y );

// returns [ [ 0.0, 0.0 ], [ 0.0, 0.0 ], [ 0.0, 0.0 ] ]

```

## Notes

-   An output [`ndarray`][@stdlib/ndarray/ctor] **must** be writable. If provided a **read-only** [`ndarray`][@stdlib/ndarray/ctor], the function throws an error.

-   A **slice argument** must be either a [`Slice`][@stdlib/slice/ctor], an integer, `null`, or `undefined`.

-   The number of slice dimensions must match the number of output array dimensions. Hence, if `y` is a zero-dimensional [`ndarray`][@stdlib/ndarray/ctor], then, if `s` is a [`MultiSlice`][@stdlib/slice/multi], `s` should be empty, and, if `s` is an array, `s` should not contain any slice arguments. Similarly, if `y` is a one-dimensional [`ndarray`][@stdlib/ndarray/ctor], then, if `s` is a [`MultiSlice`][@stdlib/slice/multi], `s` should have one slice dimension, and, if `s` is an array, `s` should contain a single slice argument. And so on and so forth.

-   The input [`ndarray`][@stdlib/ndarray/ctor] **must** be [broadcast compatible][@stdlib/ndarray/base/broadcast-shapes] with the output [`ndarray`][@stdlib/ndarray/ctor] view.

-   The input [`ndarray`][@stdlib/ndarray/ctor] must have a [data type][@stdlib/ndarray/dtypes] which can be [safely cast][@stdlib/ndarray/safe-casts] to the output [`ndarray`][@stdlib/ndarray/ctor] data type. Floating-point data types (both real and complex) are allowed to downcast to a lower precision data type of the [same kind][@stdlib/ndarray/same-kind-casts] (e.g., element values from a `'float64'` input [`ndarray`][@stdlib/ndarray/ctor] can be assigned to corresponding elements in a `'float32'` output [`ndarray`][@stdlib/ndarray/ctor]).

## Examples

```javascript

var E = require( '@stdlib/slice-multi' );

var scalar2ndarray = require( '@stdlib/ndarray-from-scalar' );

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

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

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

var sliceAssign = require( '@stdlib/ndarray-slice-assign' );

// Alias `null` to allow for more compact indexing expressions:

var _ = null;

// Create an output ndarray:

var y = ndzeros( [ 3, 3, 3 ] );

// Update each matrix...

var s1 = E( 0, _, _ );

sliceAssign( scalar2ndarray( 100 ), y, s1 );

var a1 = ndarray2array( slice( y, s1 ) );

// returns [ [ 100, 100, 100 ], [ 100, 100, 100 ], [ 100, 100, 100 ] ]

var s2 = E( 1, _, _ );

sliceAssign( scalar2ndarray( 200 ), y, s2 );

var a2 = ndarray2array( slice( y, s2 ) );

// returns [ [ 200, 200, 200 ], [ 200, 200, 200 ], [ 200, 200, 200 ] ]

var s3 = E( 2, _, _ );

sliceAssign( scalar2ndarray( 300 ), y, s3 );

var a3 = ndarray2array( slice( y, s3 ) );

// returns [ [ 300, 300, 300 ], [ 300, 300, 300 ], [ 300, 300, 300 ] ]

// Update the second rows in each matrix:

var s4 = E( _, 1, _ );

sliceAssign( scalar2ndarray( 400 ), y, s4 );

var a4 = ndarray2array( slice( y, s4 ) );

// returns [ [ 400, 400, 400 ], [ 400, 400, 400 ], [ 400, 400, 400 ] ]

// Update the second columns in each matrix:

var s5 = E( _, _, 1 );

sliceAssign( scalar2ndarray( 500 ), y, s5 );

var a5 = ndarray2array( slice( y, s5 ) );

// returns [ [ 500, 500, 500 ], [ 500, 500, 500 ], [ 500, 500, 500 ] ]

// Return the contents of the entire ndarray:

var a6 = ndarray2array( y );

/* returns

  [

    [

      [ 100, 500, 100 ],

      [ 400, 500, 400 ],

      [ 100, 500, 100 ]

    ],

    [

      [ 200, 500, 200 ],

      [ 400, 500, 400 ],

      [ 200, 500, 200 ]

    ],

    [

      [ 300, 500, 300 ],

      [ 400, 500, 400 ],

      [ 300, 500, 300 ]

    ]

  ]

*/

```

* * *

## See Also

-   [`@stdlib/ndarray-array`][@stdlib/ndarray/array]: multidimensional arrays.

-   [`@stdlib/ndarray-ctor`][@stdlib/ndarray/ctor]: multidimensional array constructor.

-   [`@stdlib/ndarray-slice`][@stdlib/ndarray/slice]: return a read-only view of an input ndarray.

* * *

## 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 © 2016-2025. The Stdlib [Authors][stdlib-authors].

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[npm-url]: https://npmjs.org/package/@stdlib/ndarray-slice-assign

[test-image]: https://github.com/stdlib-js/ndarray-slice-assign/actions/workflows/test.yml/badge.svg?branch=main

[test-url]: https://github.com/stdlib-js/ndarray-slice-assign/actions/workflows/test.yml?query=branch:main

[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/ndarray-slice-assign/main.svg

[coverage-url]: https://codecov.io/github/stdlib-js/ndarray-slice-assign?branch=main

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[chat-url]: https://app.gitter.im/#/room/#stdlib-js_stdlib:gitter.im

[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-slice-assign/tree/deno

[deno-readme]: https://github.com/stdlib-js/ndarray-slice-assign/blob/deno/README.md

[umd-url]: https://github.com/stdlib-js/ndarray-slice-assign/tree/umd

[umd-readme]: https://github.com/stdlib-js/ndarray-slice-assign/blob/umd/README.md

[esm-url]: https://github.com/stdlib-js/ndarray-slice-assign/tree/esm

[esm-readme]: https://github.com/stdlib-js/ndarray-slice-assign/blob/esm/README.md

[branches-url]: https://github.com/stdlib-js/ndarray-slice-assign/blob/main/branches.md

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

[@stdlib/slice/ctor]: https://github.com/stdlib-js/slice-ctor

[@stdlib/slice/multi]: https://github.com/stdlib-js/slice-multi

[@stdlib/ndarray/base/broadcast-shapes]: https://github.com/stdlib-js/ndarray-base-broadcast-shapes

[@stdlib/ndarray/safe-casts]: https://github.com/stdlib-js/ndarray-safe-casts

[@stdlib/ndarray/same-kind-casts]: https://github.com/stdlib-js/ndarray-same-kind-casts

[@stdlib/ndarray/dtypes]: https://github.com/stdlib-js/ndarray-dtypes

[@stdlib/ndarray/ctor]: https://github.com/stdlib-js/ndarray-ctor

[@stdlib/ndarray/array]: https://github.com/stdlib-js/ndarray-array

[@stdlib/ndarray/slice]: https://github.com/stdlib-js/ndarray-slice
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