npm package: @stdlib/utils-bifurcate
Description: Split values into two groups.
Author: The Stdlib Authors
Latest version: 0.2.3

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# bifurcate

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> Split values into two groups.

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<section class="intro">

</section>

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<!-- Package usage documentation. -->

<section class="installation">

## Installation

```bash
npm install @stdlib/utils-bifurcate
```

</section>

<section class="usage">

## Usage

```javascript
var bifurcate = require( '@stdlib/utils-bifurcate' );
```

#### bifurcate( collection, \[options,] filter )

Splits values into two groups. If an element in `filter` is truthy, the corresponding element in `collection` belongs to the first group; otherwise, the `collection` element belongs to the second group.

```javascript
var arr = [ 'beep', 'boop', 'foo', 'bar' ];
var filter = [ true, true, false, true ];

var out = bifurcate( arr, filter );
// returns [ [ 'beep', 'boop', 'bar' ], [ 'foo' ] ]
```

The function accepts the following `options`:

-   **returns**: specifies the output format. If the option equals `'values'`, the function outputs element values. If the option equals `'indices'`, the function outputs element indices. If the option equals `'*'`, the function outputs both element indices and values. Default: `'values'`.

By default, the function returns element values. To return element indices, set the `returns` option to `'indices'`.

```javascript
var arr = [ 'beep', 'boop', 'foo', 'bar' ];
var filter = [ true, true, false, true ];

var opts = {
    'returns': 'indices'
};
var out = bifurcate( arr, opts, filter );
// returns [ [ 0, 1, 3 ], [ 2 ] ]
```

To return index-element pairs, set the `returns` option to `'*'`.

```javascript
var arr = [ 'beep', 'boop', 'foo', 'bar' ];
var filter = [ true, true, false, true ];

var opts = {
    'returns': '*'
};
var out = bifurcate( arr, opts, filter );
// returns [ [ [ 0, 'beep' ], [ 1, 'boop' ], [ 3, 'bar' ] ], [ [ 2, 'foo' ] ] ]
```

</section>

<!-- /.usage -->

<!-- Package usage notes. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->

<section class="notes">

## Notes

-   Both `collection` and `filter` **must** be collections. A collection may be either an [`Array`][mdn-array], [`Typed Array`][mdn-typed-array], or an array-like [`Object`][mdn-object] (excluding `strings` and `functions`).

</section>

<!-- /.notes -->

<!-- Package usage examples. -->

<section class="examples">

## Examples

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

```javascript
var randu = require( '@stdlib/random-base-randu' );
var floor = require( '@stdlib/math-base-special-floor' );
var bifurcate = require( '@stdlib/utils-bifurcate' );

var vals;
var arr;
var out;
var f;
var i;
var j;

vals = [ 'beep', 'boop', 'foo', 'bar', 'woot', 'woot' ];

// Generate a random collection...
arr = new Array( 100 );
for ( i = 0; i < arr.length; i++ ) {
    j = floor( randu()*vals.length );
    arr[ i ] = vals[ j ];
}

// Randomly assign collection values to a group...
f = new Array( arr.length );
for ( i = 0; i < arr.length; i++ ) {
    f[ i ] = ( randu() < 0.5 );
}

// Compute the groups:
out = bifurcate( arr, f );
console.log( out );
```

</section>

<!-- /.examples -->

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<section class="references">

</section>

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<section class="related">

* * *

## See Also

-   <span class="package-name">[`@stdlib/utils-bifurcate-by`][@stdlib/utils/bifurcate-by]</span><span class="delimiter">: </span><span class="description">split values into two groups according to a predicate function.</span>
-   <span class="package-name">[`@stdlib/object-bifurcate-own`][@stdlib/object/bifurcate-own]</span><span class="delimiter">: </span><span class="description">split an object's own property values into two groups according to a predicate function.</span>
-   <span class="package-name">[`@stdlib/utils-group`][@stdlib/utils/group]</span><span class="delimiter">: </span><span class="description">group values as arrays associated with distinct keys.</span>

</section>

<!-- /.related -->

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<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

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---

## License

See [LICENSE][stdlib-license].


## Copyright

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

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[umd]: https://github.com/umdjs/umd
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[deno-url]: https://github.com/stdlib-js/utils-bifurcate/tree/deno
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[mdn-array]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array

[mdn-typed-array]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray

[mdn-object]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object

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