@stdlib/array/base/bifurcate-indices/README.md

Arrays.

<!--

@license Apache-2.0

Copyright (c) 2023 The Stdlib Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

-->

# bifurcateIndices

> Split array element indices into two groups.

<!-- Section to include introductory text. Make sure to keep an empty line after the intro `section` element and another before the `/section` close. -->

<section class="intro">

</section>

<!-- /.intro -->

<!-- Package usage documentation. -->

<section class="usage">

## Usage

```javascript
var bifurcateIndices = require( '@stdlib/array/base/bifurcate-indices' );
```

#### bifurcateIndices( x, filter )

Splits array element indices into two groups.

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

var out = bifurcateIndices( x, filter );
// returns [ [ 0, 1, 3 ], [ 2 ] ]
```

</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

-   If an element in `filter` is truthy, the corresponding element in the input array `x` belongs to the first group; otherwise, the input array element belongs to the second group.

</section>

<!-- /.notes -->

<!-- Package usage examples. -->

<section class="examples">

## Examples

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

```javascript
var discreteUniform = require( '@stdlib/random/array/discrete-uniform' );
var take = require( '@stdlib/array/base/take-indexed' );
var bifurcateIndices = require( '@stdlib/array/base/bifurcate-indices' );

// Define an initial array of values:
var values = [ 'beep', 'boop', 'foo', 'bar', 'woot', 'woot' ];

// Sample from the initial array to generate a random collection:
var indices = discreteUniform( 100, 0, values.length-1, {
    'dtype': 'generic'
});
var x = take( values, indices );
// returns [...]

// Randomly assign collection values to groups:
var groups = discreteUniform( x.length, 0, 1, {
    'dtype': 'generic'
});

// Group the values:
var out = bifurcateIndices( x, groups );
// returns [...]

console.log( out );
```

</section>

<!-- /.examples -->

<!-- Section to include cited references. If references are included, add a horizontal rule *before* the section. Make sure to keep an empty line after the `section` element and another before the `/section` close. -->

<section class="references">

</section>

<!-- /.references -->

<!-- Section for related `stdlib` packages. 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">

</section>

<!-- /.links -->