@stdlib/array/base/cuany-by/README.md

Arrays.

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# cuanyBy

> Cumulatively test whether at least one element in a provided array passes a test implemented by a predicate function.

<section class="usage">

## Usage

```javascript
var cuanyBy = require( '@stdlib/array/base/cuany-by' );
```

#### cuanyBy( x, predicate\[, thisArg] )

Cumulatively tests whether at least one element in a provided array passes a test implemented by a `predicate` function.

```javascript
function isPositive( value ) {
    return ( value > 0 );
}

var x = [ 0, 0, 0, 1, 0 ];

var y = cuanyBy( x, isPositive );
// returns [ false, false, false, true, true ]
```

The `predicate` function is provided three arguments:

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

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

```javascript
function isPositive( value ) {
    this.count += 1;
    return ( value > 0 );
}

var x = [ 0, 0, 0, 1, 0 ];

var context = {
    'count': 0
};

var out = cuanyBy( x, isPositive, context );
// returns [ false, false, false, true, true ]

var cnt = context.count;
// returns 4
```

#### cuanyBy.assign( x, out, stride, offset, predicate\[, thisArg] )

Cumulatively tests whether at least one element in a provided array passes a test implemented by a `predicate` function and assigns results to a provided output array.

```javascript
function isPositive( value ) {
    return ( value > 0 );
}

var x = [ 0, 0, 0, 1, 0 ];
var y = [ false, null, false, null, false, null, false, null, false, null ];

var out = cuanyBy.assign( x, y, 2, 0, isPositive );
// returns [ false, null, false, null, false, null, true, null, true, null ]

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

The function supports the following parameters:

-   **x**: input array.
-   **out**: output array.
-   **stride**: output array stride.
-   **offset**: output array offset.
-   **predicate**: test function.

</section>

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<section class="notes">

</section>

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<section class="examples">

## Examples

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

```javascript
var bernoulli = require( '@stdlib/random/array/bernoulli' );
var cuanyBy = require( '@stdlib/array/base/cuany-by' );

function isPositive( value ) {
    return ( value > 0 );
}

// Create an array of random values:
var x = bernoulli( 10, 0.1 );
console.log( x );

// Cumulatively determine whether at least one element is positive:
var out = cuanyBy( x, isPositive );
console.log( out );
```

</section>

<!-- /.examples -->

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