npm package: @stdlib/ndarray-concat
Description: Concatenate a list of ndarrays along a specified ndarray dimension.
Author: The Stdlib Authors
Latest version: 0.1.1

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# concat

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> Concatenate a list of [ndarrays][@stdlib/ndarray/ctor] along a specified [ndarray][@stdlib/ndarray/ctor] dimension.

<!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. -->

<section class="intro">

</section>

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<!-- Package usage documentation. -->

<section class="installation">

## Installation

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

</section>

<section class="usage">

## Usage

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

#### concat( arrays\[, options] )

Concatenates a list of [ndarrays][@stdlib/ndarray/ctor] along a specified [ndarray][@stdlib/ndarray/ctor] dimension.

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

var x = array( [ [ -1.0, 2.0 ], [ -3.0, 4.0 ] ] );
var y = array( [ [ -5.0, 6.0, -7.0 ], [ 8.0, -9.0, 10.0 ] ] );

var out = concat( [ x, y ], {
    'dim': -1
});
// returns <ndarray>[ [ -1.0, 2.0, -5.0, 6.0, -7.0 ], [ -3.0, 4.0, 8.0, -9.0, 10.0 ] ]
```

The function accepts the following arguments:

-   **arrays**: a list of input [ndarrays][@stdlib/ndarray/ctor]. Must be [broadcast compatible][@stdlib/ndarray/base/broadcast-shapes] except for the dimension along which to concatenate. The data type of the output [ndarray][@stdlib/ndarray/ctor] is determined by applying [type promotion rules][@stdlib/ndarray/promotion-rules] to the list of input [ndarrays][@stdlib/ndarray/ctor]. If provided [ndarrays][@stdlib/ndarray/ctor] having different [memory layouts][@stdlib/ndarray/orders], the output [ndarray][@stdlib/ndarray/ctor] has the [default order][@stdlib/ndarray/defaults].
-   **options**: function options (_optional_).

The function accepts the following `options`:

-   **dim**: dimension along which to concatenate input [ndarrays][@stdlib/ndarray/ctor]. Must be a negative integer. The index of the dimension along which to concatenate is resolved relative to the last dimension, with the last dimension corresponding to the value `-1`. Default: `-1`.

#### concat.assign( arrays, out\[, options] )

Concatenates a list of ndarrays along a specified ndarray dimension and assigns results to an output ndarray.

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

var x = array( [ [ -1.0, 2.0 ], [ -3.0, 4.0 ] ] );
var y = array( [ [ -5.0, 6.0, -7.0 ], [ 8.0, -9.0, 10.0 ] ] );

var z = zeros( [ 2, 5 ] );

var out = concat.assign( [ x, y ], z, {
    'dim': -1
});
// returns <ndarray>[ [ -1.0, 2.0, -5.0, 6.0, -7.0 ], [ -3.0, 4.0, 8.0, -9.0, 10.0 ] ]

var bool = ( out === z );
// returns true
```

The function accepts the following arguments:

-   **arrays**: a list of input [ndarrays][@stdlib/ndarray/ctor]. Must be [broadcast compatible][@stdlib/ndarray/base/broadcast-shapes] except for the dimension along which to concatenate. Must [promote][@stdlib/ndarray/promotion-rules] to a [data type][@stdlib/ndarray/dtypes] which can be (mostly) [safely cast][@stdlib/ndarray/mostly-safe-casts] to the [data type][@stdlib/ndarray/dtypes] of the output [ndarray][@stdlib/ndarray/ctor].
-   **out**: output [ndarray][@stdlib/ndarray/ctor].
-   **options**: function options (_optional_).

The function accepts the following `options`:

-   **dim**: dimension along which to concatenate input [ndarrays][@stdlib/ndarray/ctor]. Must be a negative integer. The index of the dimension along which to concatenate is resolved relative to the last dimension, with the last dimension corresponding to the value `-1`. Default: `-1`.

</section>

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</section>

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<!-- Package usage examples. -->

<section class="examples">

## Examples

```javascript
var discreteUniform = require( '@stdlib/random-array-discrete-uniform' );
var ndarray = require( '@stdlib/ndarray-ctor' );
var ndarray2array = require( '@stdlib/ndarray-to-array' );
var concat = require( '@stdlib/ndarray-concat' );

var xbuf = discreteUniform( 6, 0, 10, {
    'dtype': 'generic'
});
var x = new ndarray( 'generic', xbuf, [ 2, 3 ], [ 3, 1 ], 0, 'row-major' );
console.log( ndarray2array( x ) );

var ybuf = discreteUniform( 8, 0, 10, {
    'dtype': 'generic'
});
var y = new ndarray( 'generic', ybuf, [ 2, 4 ], [ 4, 1 ], 0, 'row-major' );
console.log( ndarray2array( y ) );

var out = concat( [ x, y ] );
console.log( ndarray2array( out ) );
```

</section>

<!-- /.examples -->

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* * *

## 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].

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---

## License

See [LICENSE][stdlib-license].


## Copyright

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

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