@stdlib/utils/map3d/README.md

Standard utilities.

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# map3d

> Apply a function to each nested element in a three-dimensional nested array and assign the result to a nested element in a new three-dimensional nested array.

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## Usage

```javascript
var map3d = require( '@stdlib/utils/map3d' );
```

#### map3d( arr, fcn\[, thisArg] )

Applies a function to each nested element in a three-dimensional nested array and assigns the result to a nested element in a new three-dimensional nested array.

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

var arr = [
    [ [ -1, -2, -3 ] ],
    [ [ -4, -5, -6 ] ]
];

var out = map3d( arr, naryFunction( abs, 1 ) );
// returns [ [ [ 1, 2, 3 ] ], [ [ 4, 5, 6 ] ] ]
```

The applied function is provided the following arguments:

-   **value**: array element.
-   **indices**: current array element indices.
-   **arr**: input array.

To set the `this` context when invoking the input function, provide a `thisArg`.

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

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

function fcn( v ) {
    this.count += 1;
    return abs( v );
}

var arr = [
    [ [ -1, -2, -3 ] ],
    [ [ -4, -5, -6 ] ]
];

var ctx = {
    'count': 0
};

var out = map3d( arr, fcn, ctx );
// returns [ [ [ 1, 2, 3 ] ], [ [ 4, 5, 6 ] ] ]

var cnt = ctx.count;
// returns 6
```

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## Examples

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

```javascript
var filledarrayBy = require( '@stdlib/array/filled-by' );
var discreteUniform = require( '@stdlib/random/base/discrete-uniform' ).factory;
var naryFunction = require( '@stdlib/utils/nary-function' );
var abs2 = require( '@stdlib/math/base/special/abs2' );
var map3d = require( '@stdlib/utils/map3d' );

function nestedFill( i ) {
    var rand = discreteUniform( -10*(i+1), 10*(i+1) );
    return filledarrayBy( 10, 'float64', rand );
}

function fill() {
    return filledarrayBy( 10, 'generic', nestedFill );
}

// Create a three-dimensional nested array:
var x = filledarrayBy( 10, 'generic', fill );

// Create an explicit unary function:
var f = naryFunction( abs2, 1 );

// Compute the element-wise squared absolute value...
var y = map3d( x, f );

console.log( 'x:' );
console.log( x );

console.log( 'y:' );
console.log( y );
```

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* * *

## See Also

-   <span class="package-name">[`@stdlib/utils/map`][@stdlib/utils/map]</span><span class="delimiter">: </span><span class="description">apply a function to each element in an array and assign the result to an element in an output array.</span>
-   <span class="package-name">[`@stdlib/utils/map2d`][@stdlib/utils/map2d]</span><span class="delimiter">: </span><span class="description">apply a function to each nested element in an array of arrays and assign the result to a nested element in a new array of arrays.</span>
-   <span class="package-name">[`@stdlib/utils/map4d`][@stdlib/utils/map4d]</span><span class="delimiter">: </span><span class="description">apply a function to each nested element in a four-dimensional nested array and assign the result to a nested element in a new four-dimensional nested array.</span>
-   <span class="package-name">[`@stdlib/utils/map5d`][@stdlib/utils/map5d]</span><span class="delimiter">: </span><span class="description">apply a function to each nested element in a five-dimensional nested array and assign the result to a nested element in a new five-dimensional nested array.</span>

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[@stdlib/utils/map]: https://github.com/stdlib-js/utils/tree/main/map

[@stdlib/utils/map2d]: https://github.com/stdlib-js/utils/tree/main/map2d

[@stdlib/utils/map4d]: https://github.com/stdlib-js/utils/tree/main/map4d

[@stdlib/utils/map5d]: https://github.com/stdlib-js/utils/tree/main/map5d

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