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292 changes: 292 additions & 0 deletions lib/node_modules/@stdlib/ndarray/any-by/README.md
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# anyBy

> Test whether at least one element along one or more [`ndarray`][@stdlib/ndarray/ctor] dimensions passes a test implemented by a predicate function.
<section class="intro">

</section>

<!-- /.intro -->

<section class="usage">

## Usage

```javascript
var anyBy = require( '@stdlib/ndarray/any-by' );
```

#### anyBy( x\[, options], predicate\[, thisArg] )

Tests whether at least one element along one or more [`ndarray`][@stdlib/ndarray/ctor] dimensions passes a test implemented by a predicate function.

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

function isPositive( value ) {
return value > 0.0;
}

// Create an input ndarray:
var x = array( [ [ 1.0, -2.0 ], [ 3.0, -4.0 ] ] );

// Test whether at least one element is positive:
var out = anyBy( x, isPositive );
// returns <ndarray>

var v = out.get();
// returns true
```

The function accepts the following arguments:

- **x**: input [`ndarray`][@stdlib/ndarray/ctor].
- **options**: function options _(optional)_.
- **predicate**: predicate function.
- **thisArg**: predicate function execution context _(optional)_.

The function accepts the following options:

- **dims**: list of dimensions over which to perform a reduction.
- **keepdims**: boolean indicating whether the reduced dimensions should be included in the returned [`ndarray`][@stdlib/ndarray/ctor] as singleton dimensions. Default: `false`.

By default, the function performs a reduction over all elements in a provided [`ndarray`][@stdlib/ndarray/ctor]. To reduce specific dimensions, set the `dims` option.

```javascript
var ndarray2array = require( '@stdlib/ndarray/to-array' );
var array = require( '@stdlib/ndarray/array' );

function isPositive( value ) {
return value > 0.0;
}

// Create an input ndarray:
var x = array( [ [ 1.0, 2.0 ], [ -3.0, -4.0 ] ] );

var opts = {
'dims': [ 1 ]
};

// Perform reduction:
var out = anyBy( x, opts, isPositive );
// returns <ndarray>

var v = ndarray2array( out );
// returns [ true, false ]
```

By default, the function returns an [`ndarray`][@stdlib/ndarray/ctor] having a shape matching only the non-reduced dimensions of the input [`ndarray`][@stdlib/ndarray/ctor] (i.e., the reduced dimensions are dropped). To include the reduced dimensions as singleton dimensions in the output [`ndarray`][@stdlib/ndarray/ctor], set the `keepdims` option to `true`.

```javascript
var ndarray2array = require( '@stdlib/ndarray/to-array' );
var array = require( '@stdlib/ndarray/array' );

function isPositive( value ) {
return value > 0.0;
}

// Create an input ndarray:
var x = array( [ [ 1.0, 2.0 ], [ -3.0, -4.0 ] ] );

var opts = {
'keepdims': true
};

// Perform reduction:
var out = anyBy( x, opts, isPositive );
// returns <ndarray>

var v = ndarray2array( out );
// returns [ [ [ true ] ] ]
```

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

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

function isPositive( value ) {
this.count += 1;
return value > 0.0;
}

// Create an input ndarray:
var x = array( [ [ -1.0, -2.0 ], [ -3.0, 4.0 ] ] );
// returns <ndarray>

// Create a context object:
var ctx = {
'count': 0
};

// Perform reduction:
var out = anyBy( x, isPositive, ctx );
// returns <ndarray>

var v = out.get();
// returns true

var count = ctx.count;
// returns 4
```

#### anyBy.assign( x, y\[, options], predicate\[, thisArg] )

Tests whether at least one element along one or more [`ndarray`][@stdlib/ndarray/ctor] dimensions passes a test implemented by a predicate function and assigns the result to a provided output [`ndarray`][@stdlib/ndarray/ctor].

```javascript
var array = require( '@stdlib/ndarray/array' );
var empty = require( '@stdlib/ndarray/empty' );

function isPositive( value ) {
return value > 0.0;
}

// Create an input ndarray:
var x = array( [ [ 1.0, -2.0 ], [ 3.0, -4.0 ] ] );

// Create an output ndarray:
var y = empty( [], {
'dtype': 'bool'
});

// Perform reduction:
var out = anyBy.assign( x, y, isPositive );
// returns <ndarray>

var v = out.get();
// returns true

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

The function accepts the following arguments:

- **x**: input [`ndarray`][@stdlib/ndarray/ctor].
- **y**: output [`ndarray`][@stdlib/ndarray/ctor]. The output [`ndarray`][@stdlib/ndarray/ctor] must have a shape matching the non-reduced dimensions of the input [`ndarray`][@stdlib/ndarray/ctor].
- **options**: function options _(optional)_.
- **predicate**: predicate function.
- **thisArg**: predicate function execution context _(optional)_.

The function accepts the following options:

- **dims**: list of dimensions over which to perform a reduction.

By default, the function performs a reduction over all elements in a provided [`ndarray`][@stdlib/ndarray/ctor]. To reduce specific dimensions, set the `dims` option.

```javascript
var array = require( '@stdlib/ndarray/array' );
var empty = require( '@stdlib/ndarray/empty' );
var ndarray2array = require( '@stdlib/ndarray/to-array' );

function predicate( value ) {
return value > 0.0;
}

// Create an input ndarray:
var x = array( [ [ 1.0, 2.0 ], [ -3.0, -4.0 ] ] );
// returns <ndarray>

// Create an output ndarray:
var y = empty( [ 2 ], {
'dtype': 'bool'
});

var opts = {
'dims': [ 1 ]
};

// Perform reduction:
var out = anyBy.assign( x, y, opts, predicate );

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

var v = ndarray2array( y );
// returns [ true, false ]
```

</section>

<!-- /.usage -->

<section class="notes">

## Notes

- The predicate function is provided the following arguments:

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

</section>

<!-- /.notes -->

<section class="examples">

## Examples

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

```javascript
var discreteUniform = require( '@stdlib/random/base/discrete-uniform' ).factory;
var isEven = require( '@stdlib/assert/is-even' ).isPrimitive;
var ndarray2array = require( '@stdlib/ndarray/to-array' );
var fillBy = require( '@stdlib/ndarray/fill-by' );
var zeros = require( '@stdlib/ndarray/zeros' );
var anyBy = require( '@stdlib/ndarray/any-by' );

var x = zeros( [ 2, 4, 5 ], {
'dtype': 'float64'
});
x = fillBy( x, discreteUniform( 0, 10 ) );
console.log( ndarray2array( x ) );

var y = anyBy( x, isEven );
console.log( y.get() );
```

</section>

<!-- /.examples -->

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

<section class="related">

</section>

<!-- /.related -->

<!-- Section for all links. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->

<section class="links">

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

</section>

<!-- /.links -->
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