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# forEach

> Invoke a callback function once for each element in an ndarray.

<section class="intro">

</section>

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<section class="usage">

## Usage

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

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

Invokes a callback function once for each element in an ndarray.

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

// Create data buffers:
var xbuf = new Float64Array( 12 );

// Define the shape of the array:
var shape = [ 3, 1, 2 ];

// Define the array strides:
var sx = [ 4, 4, 1 ];

// Define the index offset:
var ox = 1;

// Create an ndarray-like object:
var x = {
    'dtype': 'float64',
    'data': xbuf,
    'shape': shape,
    'strides': sx,
    'offset': ox,
    'order': 'row-major'
};

// Apply the callback function:
forEach( [ x ], naryFunction( log, 1 ) );
```

The function accepts the following arguments:

-   **arrays**: array-like object containing an input ndarray.
-   **fcn**: callback to apply.
-   **thisArg**: callback execution context.

The callback function is provided the following arguments:

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

</section>

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<section class="notes">

## Notes

-   The provided ndarray should be an object with the following properties:

    -   **dtype**: data type.
    -   **data**: data buffer.
    -   **shape**: dimensions.
    -   **strides**: stride lengths.
    -   **offset**: index offset.
    -   **order**: specifies whether an ndarray is row-major (C-style) or column major (Fortran-style).

-   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>

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<section class="examples">

## Examples

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

```javascript
var ndarray2array = require( '@stdlib/ndarray/base/to-array' );
var zeroTo = require( '@stdlib/array/base/zero-to' );
var naryFunction = require( '@stdlib/utils/nary-function' );
var log = require( '@stdlib/console/log' );
var forEach = require( '@stdlib/ndarray/base/for-each' );

var x = {
    'dtype': 'generic',
    'data': zeroTo( 10 ),
    'shape': [ 5, 2 ],
    'strides': [ -2, 1 ],
    'offset': 8,
    'order': 'row-major'
};

log( ndarray2array( x.data, x.shape, x.strides, x.offset, x.order ) );
forEach( [ x ], naryFunction( log, 2 ) );

x = {
    'dtype': 'generic',
    'data': zeroTo( 10 ),
    'shape': [ 5, 2 ],
    'strides': [ 1, -5 ],
    'offset': 5,
    'order': 'column-major'
};

log( ndarray2array( x.data, x.shape, x.strides, x.offset, x.order ) );
forEach( [ x ], naryFunction( log, 2 ) );

x = {
    'dtype': 'generic',
    'data': zeroTo( 18 ),
    'shape': [ 2, 3, 3 ],
    'strides': [ 9, 3, 1 ],
    'offset': 0,
    'order': 'row-major'
};

log( ndarray2array( x.data, x.shape, x.strides, x.offset, x.order ) );
forEach( [ x ], naryFunction( log, 2 ) );

x = {
    'dtype': 'generic',
    'data': zeroTo( 18 ),
    'shape': [ 2, 3, 3 ],
    'strides': [ -1, -2, -6 ],
    'offset': 17,
    'order': 'column-major'
};

log( ndarray2array( x.data, x.shape, x.strides, x.offset, x.order ) );
forEach( [ x ], naryFunction( log, 2 ) );
```

</section>

<!-- /.examples -->

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<section class="related">

</section>

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<section class="links">

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</section>

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