<!--

@license Apache-2.0

Copyright (c) 2025 The Stdlib Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

-->

# flattenShapeFrom

> Flatten a shape starting from a specified 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>

<!-- /.intro -->

<!-- Package usage documentation. -->

<section class="usage">

## Usage

```javascript
var flattenShapeFrom = require( '@stdlib/ndarray/base/flatten-shape-from' );
```

#### flattenShapeFrom( shape, dim )

Flattens a shape starting from a specified dimension.

```javascript
var sh = flattenShapeFrom( [ 3, 3, 2 ], 1 );
// returns [ 3, 6 ]
```

The function accepts the following parameters:

-   **shape**: array shape.
-   **dim**: dimension to start flattening from.

#### flattenShapeFrom.assign( shape, dim, out )

Flattens a shape starting from a specified dimension and assigns results to a provided output array.

```javascript
var sh = [ 0, 0 ];

var out = flattenShapeFrom.assign( [ 3, 3, 2 ], 1, sh );
// returns [ 3, 6 ]

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

The function accepts the following parameters:

-   **shape**: array shape.
-   **dim**: dimension to start flattening from. If provided an integer less than zero, the dimension index is resolved relative to the last dimension, with the last dimension corresponding to the value `-1`.
-   **out**: output array.

</section>

<!-- /.usage -->

<!-- Package usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->

<section class="notes">

</section>

<!-- /.notes -->

<!-- Package usage examples. -->

<section class="examples">

## Examples

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

```javascript
var discreteUniform = require( '@stdlib/random/array/discrete-uniform' );
var zip = require( '@stdlib/array/base/zip' );
var logEachMap = require( '@stdlib/console/log-each-map' );
var flattenShapeFrom = require( '@stdlib/ndarray/base/flatten-shape-from' );

var opts = {
    'dtype': 'int32'
};
var d1 = discreteUniform( 100, 1, 10, opts );
var d2 = discreteUniform( d1.length, 1, 10, opts );
var d3 = discreteUniform( d1.length, 1, 10, opts );
var d4 = discreteUniform( d1.length, 1, 10, opts );

var dims = discreteUniform( d1.length, -4, 3, opts );
var shapes = zip( [ d1, d2, d3, d4 ] );

logEachMap( 'shape: (%s). dim: %d. flattened: (%s).', shapes, dims, flattenShapeFrom );
```

</section>

<!-- /.examples -->

<!-- C interface documentation. -->

* * *

<section class="c">

## C APIs

<!-- 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>

<!-- /.intro -->

<!-- C usage documentation. -->

<section class="usage">

### Usage

```c
#include "stdlib/ndarray/base/flatten_shape_from.h"
```

#### stdlib_ndarray_flatten_shape_from( ndims, \*shape, dim, \*out )

Flattens a shape starting from a specified dimension.

```c
#include <stdint.h>

const int64_t ndims = 3;
const int64_t shape[] = { 2, 3, 10 };
int64_t out[ 2 ];

stdlib_ndarray_flatten_shape_from( ndims, shape, 1, out );
```

The function accepts the following arguments:

-   **ndims**: `[in] int64_t` number of dimensions.
-   **shape**: `[in] int64_t*` array shape (dimensions).
-   **dim**: `[in] int64_t` dimension to start flattening from.
-   **out**: `[out] int64_t*` output array.

```c
int8_t stdlib_ndarray_flatten_shape_from( const int64_t ndims, const int64_t *shape, const int64_t dim, int64_t *out );
```

</section>

<!-- /.usage -->

<!-- C API usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->

<section class="notes">

</section>

<!-- /.notes -->

<!-- C API usage examples. -->

<section class="examples">

### Examples

```c
#include "stdlib/ndarray/base/flatten_shape_from.h"
#include <stdio.h>
#include <inttypes.h>

int main( void ) {
    const int64_t shape[] = { 2, 3, 4, 10 };
    const int64_t ndims = 4;
    const int64_t dim = 2;
    int64_t out[ 3 ];

    stdlib_ndarray_flatten_shape_from( ndims, shape, dim, out );

    int i;
    printf( "shape = ( " );
    for ( i = 0; i < ndims-dim+1; i++ ) {
        printf( "%"PRId64"", out[ i ] );
        if ( i < ndims-dim ) {
            printf( ", " );
        }
    }
    printf( " )\n" );
}
```

</section>

<!-- /.examples -->

</section>

<!-- /.c -->

<!-- Section to include cited references. If references are included, add a horizontal rule *before* the section. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->

<section class="references">

</section>

<!-- /.references -->

<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. -->

<section class="related">

</section>

<!-- /.related -->

<!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->

<section class="links">

</section>

<!-- /.links -->
