npm package: @stdlib/ndarray-base-find
Description: Return the first element in an ndarray which passes a test implemented by a predicate function.
Author: The Stdlib Authors
Latest version: 0.1.1

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</details>

# find

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> Return the first element in an ndarray which passes a test implemented by a predicate function.

<section class="intro">

</section>

<!-- /.intro -->

<section class="installation">

## Installation

```bash
npm install @stdlib/ndarray-base-find
```

</section>

<section class="usage">

## Usage

<!-- eslint-disable no-redeclare -->

```javascript
var find = require( '@stdlib/ndarray-base-find' );
```

<!-- eslint-enable no-redeclare -->

#### find( arrays, predicate\[, thisArg] )

Returns the first element in an ndarray which passes a test implemented by a predicate function.

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

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

function isEven( value ) {
    return value % 2.0 === 0.0;
}

// Create a data buffer:
var xbuf = 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 ] );

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

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

// Define the index offset:
var ox = 0;

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

// Create an ndarray-like object containing a sentinel value:
var sentinelValue = {
    'dtype': 'float64',
    'data': new Float64Array( [ NaN ] ),
    'shape': [],
    'strides': [ 0 ],
    'offset': 0,
    'order': 'row-major'
};

// Perform reduction:
var out = find( [ x, sentinelValue ], isEven );
// returns 2.0
```

The function accepts the following arguments:

-   **arrays**: array-like object containing an input ndarray and a zero-dimensional ndarray containing a sentinel value. The sentinel value is returned when no element in an input ndarray passes a test implemented by the predicate function.
-   **predicate**: predicate function.
-   **thisArg**: predicate function execution context (_optional_).

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

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

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

function isEven( value ) {
    this.count += 1;
    return value % 2.0 === 0.0;
}

// Create a data buffer:
var xbuf = 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 ] );

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

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

// Define the index offset:
var ox = 0;

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

// Create an ndarray-like object containing a sentinel value:
var sentinelValue = {
    'dtype': 'float64',
    'data': new Float64Array( [ NaN ] ),
    'shape': [],
    'strides': [ 0 ],
    'offset': 0,
    'order': 'row-major'
};

var ctx = {
    'count': 0
};

// Perform reduction:
var out = find( [ x, sentinelValue ], isEven, ctx );
// returns 2.0

var count = ctx.count;
// returns 2
```

</section>

<!-- /.usage -->

<section class="notes">

## Notes

-   Each 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).

-   The predicate function is provided the following arguments:

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

-   For very high-dimensional ndarrays which are non-contiguous, one should consider copying the underlying data to contiguous memory before performing the operation 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 Float64Array = require( '@stdlib/array-float64' );
var ndarray2array = require( '@stdlib/ndarray-base-to-array' );
var find = require( '@stdlib/ndarray-base-find' );

function isEven( value ) {
    return value % 2.0 === 0.0;
}

var x = {
    'dtype': 'float64',
    'data': discreteUniform( 10, 0.0, 10.0, {
        'dtype': 'float64'
    }),
    'shape': [ 5, 2 ],
    'strides': [ 2, 1 ],
    'offset': 0,
    'order': 'row-major'
};
console.log( ndarray2array( x.data, x.shape, x.strides, x.offset, x.order ) );

var sv = {
    'dtype': 'float64',
    'data': new Float64Array( [ NaN ] ),
    'shape': [],
    'strides': [ 0 ],
    'offset': 0,
    'order': x.order
};
console.log( 'Sentinel Value: %d', sv.data[ 0 ] );

var out = find( [ x, sv ], isEven );
console.log( out );
```

</section>

<!-- /.examples -->

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

<section class="related">

</section>

<!-- /.related -->


<section class="main-repo" >

* * *

## Notice

This package is part of [stdlib][stdlib], a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.

For more information on the project, filing bug reports and feature requests, and guidance on how to develop [stdlib][stdlib], see the main project [repository][stdlib].

#### Community

[![Chat][chat-image]][chat-url]

---

## License

See [LICENSE][stdlib-license].


## Copyright

Copyright &copy; 2016-2026. The Stdlib [Authors][stdlib-authors].

</section>

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</section>

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