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# forEach

> Invoke a callback function once for each [ndarray][@stdlib/ndarray/ctor] element.

<section class="intro">

</section>

<!-- /.intro -->

<section class="usage">

## Usage

```javascript
var forEach = require( '@stdlib/ndarray/for-each' );
```

#### forEach( x, fcn\[, thisArg] )

Invokes a callback function once for each [ndarray][@stdlib/ndarray/ctor] element.

<!-- eslint-disable max-len -->

```javascript
var Float64Array = require( '@stdlib/array/float64' );
var ndarray = require( '@stdlib/ndarray/ctor' );
var naryFunction = require( '@stdlib/utils/nary-function' );
var log = require( '@stdlib/console/log' );

var buffer = new Float64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, 12.0 ] );
var shape = [ 2, 3 ];
var strides = [ 6, 1 ];
var offset = 1;

var x = ndarray( 'float64', buffer, shape, strides, offset, 'row-major' );
// returns <ndarray>

forEach( x, naryFunction( log, 1 ) );
```

The function accepts the following arguments:

-   **x**: input [ndarray][@stdlib/ndarray/ctor].
-   **fcn**: callback to apply.
-   **thisArg**: callback execution context _(optional)_.

To set the callback function execution context, provide a `thisArg`.

<!-- eslint-disable no-invalid-this, max-len -->

```javascript
var Float64Array = require( '@stdlib/array/float64' );
var ndarray = require( '@stdlib/ndarray/ctor' );

function accumulate( z ) {
    this.sum += z;
}

var buffer = new Float64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, 12.0 ] );
var shape = [ 2, 3 ];
var strides = [ 6, 1 ];
var offset = 1;
var x = ndarray( 'float64', buffer, shape, strides, offset, 'row-major' );
// returns <ndarray>

var ctx = {
    'sum': 0
};

forEach( x, accumulate, ctx );
var sum = ctx.sum;
// returns 36
```

The callback function is provided the following arguments:

-   **value**: current array element.
-   **indices**: current array element indices.
-   **arr**: the input [ndarray][@stdlib/ndarray/ctor].

</section>

<!-- /.usage -->

<section class="notes">

## Notes

-   For very high-dimensional ndarrays which are non-contiguous, one should consider copying the underlying data to contiguous memory before applying a callback function in order to achieve better performance.

</section>

<!-- /.notes -->

<section class="examples">

## Examples

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

```javascript
var discreteUniform = require( '@stdlib/random/array/discrete-uniform' );
var ndarray = require( '@stdlib/ndarray/ctor' );
var ndarray2array = require( '@stdlib/ndarray/to-array' );
var naryFunction = require( '@stdlib/utils/nary-function' );
var log = require( '@stdlib/console/log' );
var forEach = require( '@stdlib/ndarray/for-each' );

var buffer = discreteUniform( 10, -100, 100, {
    'dtype': 'generic'
});
var shape = [ 5, 2 ];
var strides = [ 2, 1 ];
var offset = 0;
var x = ndarray( 'generic', buffer, shape, strides, offset, 'row-major' );

log( ndarray2array( x ) );
forEach( x, naryFunction( log, 2 ) );
```

</section>

<!-- /.examples -->

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

<section class="related">

* * *

## See Also

-   <span class="package-name">[`@stdlib/ndarray/map`][@stdlib/ndarray/map]</span><span class="delimiter">: </span><span class="description">apply a callback to elements in an input ndarray and assign results to elements in a new output ndarray.</span>

</section>

<!-- /.related -->

<section class="links">

[@stdlib/ndarray/ctor]: https://github.com/stdlib-js/ndarray/tree/main/ctor

<!-- <related-links> -->

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

<!-- </related-links> -->

</section>

<!-- /.links -->
