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# colcat

> Concatenate a list of one-dimensional or two-dimensional [ndarrays][@stdlib/ndarray/ctor] as columns.

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</section>

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## Usage

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

#### colcat( arrays )

Concatenates a list of one-dimensional or two-dimensional [ndarrays][@stdlib/ndarray/ctor] as columns.

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

var x = array( [ 1.0, 2.0, 3.0 ] );
// returns <ndarray>[ 1.0, 2.0, 3.0 ]

var y = array( [ [ 4.0, 5.0 ], [ 6.0, 7.0 ], [ 8.0, 9.0 ] ] );
// returns <ndarray>[ [ 4.0, 5.0 ], [ 6.0, 7.0 ], [ 8.0, 9.0 ] ]

var out = colcat( [ x, y ] );
// returns <ndarray>[ [ 1.0, 4.0, 5.0 ], [ 2.0, 6.0, 7.0 ], [ 3.0, 8.0, 9.0 ] ]
```

The function accepts the following arguments:

-   **arrays**: a list of input [ndarrays][@stdlib/ndarray/ctor]. 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].

#### colcat.assign( arrays, out )

Concatenates a list of one-dimensional or two-dimensional [ndarrays][@stdlib/ndarray/ctor] as columns and assigns results to a provided output [ndarray][@stdlib/ndarray/ctor].

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

var x = array( [ 1.0, 2.0, 3.0 ] );
// returns <ndarray>[ 1.0, 2.0, 3.0 ]

var y = array( [ [ 4.0, 5.0 ], [ 6.0, 7.0 ], [ 8.0, 9.0 ] ] );
// returns <ndarray>[ [ 4.0, 5.0 ], [ 6.0, 7.0 ], [ 8.0, 9.0 ] ]

var z = zeros( [ 3, 3 ] );
// returns <ndarray>[ [ 0.0, 0.0, 0.0 ], [ 0.0, 0.0, 0.0 ], [ 0.0, 0.0, 0.0 ] ]

var out = colcat.assign( [ x, y ], z );
// returns <ndarray>[ [ 1.0, 4.0, 5.0 ], [ 2.0, 6.0, 7.0 ], [ 3.0, 8.0, 9.0 ] ]

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

The function accepts the following arguments:

-   **arrays**: a list of input [ndarrays][@stdlib/ndarray/ctor]. 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]. Must be a two-dimensional [ndarray][@stdlib/ndarray/ctor].

</section>

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-   One-dimensional input [ndarrays][@stdlib/ndarray/ctor] having length `N` are promoted to two-dimensional [ndarrays][@stdlib/ndarray/ctor] having shape `[N, 1]`.
-   Input [ndarrays][@stdlib/ndarray/ctor] must have the same number of rows.

</section>

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<section class="examples">

## Examples

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

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

var x = discreteUniform( [ 3 ], 0, 10, {
    'dtype': 'generic'
});
console.log( ndarray2array( x ) );

var y = discreteUniform( [ 3, 2 ], 0, 10, {
    'dtype': 'generic'
});
console.log( ndarray2array( y ) );

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

</section>

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</section>

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

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

[@stdlib/ndarray/orders]: https://github.com/stdlib-js/ndarray/tree/main/orders

[@stdlib/ndarray/defaults]: https://github.com/stdlib-js/ndarray/tree/main/defaults

[@stdlib/ndarray/promotion-rules]: https://github.com/stdlib-js/ndarray/tree/main/promotion-rules

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

</section>

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