@stdlib/array/base/map2d/README.md

Arrays.

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# map2d

> Apply a function to elements in a two-dimensional nested input array and assign results to elements in a new two-dimensional nested output array.

<section class="intro">

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<section class="usage">

## Usage

```javascript
var map2d = require( '@stdlib/array/base/map2d' );
```

#### map2d( x, shape, fcn\[, thisArg] )

Applies a function to elements in a two-dimensional nested input array and assigns results to elements in a new two-dimensional nested output array.

```javascript
var naryFunction = require( '@stdlib/utils/nary-function' );
var abs = require( '@stdlib/math/base/special/abs' );

var x = [ [ -1.0, -2.0 ], [ -3.0, -4.0 ] ];
var shape = [ 2, 2 ];

var y = map2d( x, shape, naryFunction( abs, 1 ) );
// returns [ [ 1.0, 2.0 ], [ 3.0, 4.0 ] ]
```

The function accepts the following arguments:

-   **x**: input nested array.
-   **shape**: array shape.
-   **fcn**: function to apply.
-   **thisArg**: applied function execution context (_optional_).

To set the applied function's execution context, provide a `thisArg`.

<!-- eslint-disable no-invalid-this -->

```javascript
function fcn( x ) {
    this.count += 1;
    return x;
}

var x = [ [ 1.0, 2.0 ], [ 3.0, 4.0 ] ];
var shape = [ 2, 2 ];

var ctx = {
    'count': 0
};

var y = map2d( x, shape, fcn, ctx );
// returns [ [ 1.0, 2.0 ], [ 3.0, 4.0 ] ]

var v = ctx.count;
// returns 4
```

#### map2d.assign( x, y, shape, fcn\[, thisArg] )

Applies a function to elements in a two-dimensional nested input array and assigns results to elements in a two-dimensional nested output array.

```javascript
var naryFunction = require( '@stdlib/utils/nary-function' );
var zeros2d = require( '@stdlib/array/base/zeros2d' );
var abs = require( '@stdlib/math/base/special/abs' );

var x = [ [ -1.0, -2.0 ], [ -3.0, -4.0 ] ];
var shape = [ 2, 2 ];

var y = zeros2d( shape );

var out = map2d.assign( x, y, shape, naryFunction( abs, 1 ) );
// returns [ [ 1.0, 2.0 ], [ 3.0, 4.0 ] ]

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

The function accepts the following arguments:

-   **x**: input nested array.
-   **y**: output nested array.
-   **shape**: array shape.
-   **fcn**: function to apply.
-   **thisArg**: applied function execution context (_optional_).

The function assumes that the input and output arrays have the same shape.

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<section class="examples">

## Examples

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

```javascript
var discreteUniform = require( '@stdlib/random/base/discrete-uniform' ).factory;
var filled2dBy = require( '@stdlib/array/base/filled2d-by' );
var naryFunction = require( '@stdlib/utils/nary-function' );
var abs = require( '@stdlib/math/base/special/abs' );
var map2d = require( '@stdlib/array/base/map2d' );

var shape = [ 3, 3 ];

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

var y = map2d( x, shape, naryFunction( abs, 1 ) );
console.log( y );
```

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