@stdlib/array/base/mskunary2d/README.md

Arrays.

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# mskunary2d

> Apply a unary callback to elements in a two-dimensional nested input array according to elements in a two-dimensional nested mask array and assign results to elements in a two-dimensional nested output array.

<section class="intro">

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<section class="usage">

## Usage

```javascript
var mskunary2d = require( '@stdlib/array/base/mskunary2d' );
```

#### mskunary2d( arrays, shape, fcn )

Applies a unary callback to elements in a two-dimensional nested input array according to elements in a two-dimensional nested mask array and assigns results to elements in a two-dimensional nested output array.

```javascript
var abs = require( '@stdlib/math/base/special/abs' );

var x = [ [ -1.0, -2.0 ], [ -3.0, -4.0 ] ];
var mask = [ [ 0, 1 ], [ 0, 0 ] ];

var shape = [ 2, 2 ];

// Compute the absolute values in-place:
mskunary2d( [ x, mask, x ], shape, abs );
// x => [ [ 1.0, -2.0 ], [ 3.0, 4.0 ] ]
```

The function accepts the following arguments:

-   **arrays**: array-like object containing one input nested array, an input nested mask array, and one output nested array.
-   **shape**: array shape.
-   **fcn**: unary function to apply.

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<section class="notes">

## Notes

-   The function assumes that the input and output arrays have the same shape.
-   An element in an input array is "masked" if the corresponding element in the mask array is non-zero.

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<section class="examples">

## Examples

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```javascript
var discreteUniform = require( '@stdlib/random/base/discrete-uniform' ).factory;
var bernoulli = require( '@stdlib/random/base/bernoulli' ).factory;
var filled2dBy = require( '@stdlib/array/base/filled2d-by' );
var zeros2d = require( '@stdlib/array/base/zeros2d' );
var abs = require( '@stdlib/math/base/special/abs' );
var mskunary2d = require( '@stdlib/array/base/mskunary2d' );

var shape = [ 3, 3 ];

var x = filled2dBy( shape, discreteUniform( -100, 100 ) );
console.log( x );

var mask = filled2dBy( shape, bernoulli( 0.5 ) );
console.log( mask );

var y = zeros2d( shape );
console.log( y );

mskunary2d( [ x, mask, y ], shape, abs );
console.log( y );
```

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