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# Singleton Dimensions

> Return the number of singleton dimensions.

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## Usage

```javascript
var singletonDimensions = require( '@stdlib/ndarray/base/singleton-dimensions' );
```

#### singletonDimensions( shape )

Returns the number of singleton dimensions.

```javascript
var n = singletonDimensions( [ 3, 1, 3 ] );
// returns 1
```

</section>

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## Notes

-   A singleton dimension is a dimension whose size is equal to `1`.

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## Examples

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

```javascript
var discreteUniform = require( '@stdlib/random/base/discrete-uniform' );
var singletonDimensions = require( '@stdlib/ndarray/base/singleton-dimensions' );

var shape;
var n;
var i;

shape = [ 0, 0, 0 ];
for ( i = 0; i < 100; i++ ) {
    shape[ 0 ] = discreteUniform( 1, 5 );
    shape[ 1 ] = discreteUniform( 1, 5 );
    shape[ 2 ] = discreteUniform( 1, 5 );
    n = singletonDimensions( shape );
    console.log( 'shape: %s. singleton dimensions: %d.', shape.join( 'x' ), n );
}
```

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* * *

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## C APIs

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### Usage

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

#### stdlib_ndarray_singleton_dimensions( ndims, \*shape )

Returns the number of singleton dimensions.

```c
int64_t ndims = 2;
int64_t shape[] = { 10, 1 };

int64_t n = stdlib_ndarray_singleton_dimensions( ndims, shape );
// returns 1
```

The function accepts the following arguments:

-   **ndims**: `[in] int64_t` number of dimensions.
-   **shape**: `[in] int64_t*` array shape.

```c
int64_t stdlib_ndarray_singleton_dimensions( int64_t ndims, int64_t *shape );
```

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### Examples

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

int main( void ) {
    int64_t shape[] = { 10, 3, 1, 1, 5 };

    int64_t n = stdlib_ndarray_singleton_dimensions( 5, shape );
    printf( "shape: %"PRId64"x%"PRId64"x%"PRId64"x%"PRId64"x%"PRId64". singleton dimensions: %"PRId64"\n", shape[ 0 ], shape[ 1 ], shape[ 2 ], shape[ 3 ], shape[ 4 ], n );
}
```

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</section>

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</section>

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