@stdlib/array/base/flatten/README.md

Arrays.

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# flatten

> Flatten an n-dimensional nested array.

<section class="usage">

## Usage

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

#### flatten( x, shape, colexicographic )

Flattens an n-dimensional nested array.

```javascript
var x = [ [ 1, 2 ], [ 3, 4 ] ];

var out = flatten( x, [ 2, 2 ], false );
// returns [ 1, 2, 3, 4 ]
```

To flatten in colexicographic order, provide a third argument equal to `true`.

```javascript
var x = [ [ 1, 2 ], [ 3, 4 ] ];

var out = flatten( x, [ 2, 2 ], true );
// returns [ 1, 3, 2, 4 ]
```

#### flatten.assign( x, shape, colexicographic, out, stride, offset )

Flattens an n-dimensional nested array and assigns elements to a provided output array.

```javascript
var Float64Array = require( '@stdlib/array/float64' );

var x = [ [ 1, 2 ], [ 3, 4 ] ];
var out = new Float64Array( 4 );

var y = flatten.assign( x, [ 2, 2 ], false, out, 1, 0 );
// returns <Float64Array>[ 1, 2, 3, 4 ]

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

y = flatten.assign( x, [ 2, 2 ], true, out, 1, 0 );
// returns <Float64Array>[ 1, 3, 2, 4 ]
```

</section>

<!-- /.usage -->

<section class="notes">

## Notes

-   Both functions assume that all nested arrays have the same length (i.e., the input array is **not** a ragged array).

</section>

<!-- /.notes -->

<section class="examples">

## Examples

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

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

// Define a 2x2x1x2x2 array:
var x = [
    [
        [
            [
                [ 1, 2 ], [ 3, 4 ]
            ]
        ],
        [
            [
                [ 5, 6 ], [ 7, 8 ]
            ]
        ]
    ],
    [
        [
            [
                [ 9, 10 ], [ 11, 12 ]
            ]
        ],
        [
            [
                [ 13, 14 ], [ 15, 16 ]
            ]
        ]
    ]
];

var out = flatten( x, [ 0, 0, 0, 0, 0 ], false );
// returns []

out = flatten( x, [ 0, 0, 0, 0, 0 ], true );
// returns []

out = flatten( x, [ 1, 1, 1, 1, 1 ], false );
// returns [ 1 ]

out = flatten( x, [ 1, 1, 1, 1, 1 ], true );
// returns [ 1 ]

out = flatten( x, [ 1, 2, 1, 2, 2 ], false );
// returns [ 1, 2, 3, 4, 5, 6, 7, 8 ]

out = flatten( x, [ 1, 2, 1, 2, 2 ], true );
// returns [ 1, 5, 3, 7, 2, 6, 4, 8 ]

out = flatten( x, [ 2, 2, 1, 2, 2 ], false );
// returns [ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16 ]

out = flatten( x, [ 2, 2, 1, 2, 2 ], true );
// returns [ 1, 9, 5, 13, 3, 11, 7, 15, 2, 10, 6, 14, 4, 12, 8, 16 ]
```

</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/array/base/flatten-by`][@stdlib/array/base/flatten-by]</span><span class="delimiter">: </span><span class="description">flatten an n-dimensional nested array according to a callback function.</span>

</section>

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<section class="links">

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

[@stdlib/array/base/flatten-by]: https://github.com/stdlib-js/array/tree/main/base/flatten-by

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

</section>

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