@stdlib/array/base/bifurcate-values-by/README.md

Arrays.

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# bifurcateValuesBy

> Split element values into two groups according to a predicate function.

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## Usage

```javascript
var bifurcateValuesBy = require( '@stdlib/array/base/bifurcate-values-by' );
```

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

Splits element values into two groups according to a predicate function.

```javascript
function predicate( v ) {
    return v[ 0 ] === 'b';
}

var x = [ 'beep', 'boop', 'foo', 'bar' ];

var out = bifurcateValuesBy( x, predicate );
// returns [ [ 'beep', 'boop', 'bar' ], [ 'foo' ] ]
```

A `predicate` function is provided the following 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 predicate( v ) {
    this.count += 1;
    return v[ 0 ] === 'b';
}

var x = [ 'beep', 'boop', 'foo', 'bar' ];

var context = {
    'count': 0
};
var out = bifurcateValuesBy( x, predicate, context );
// returns [ [ 'beep', 'boop', 'bar' ], [ 'foo' ] ]

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

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## Examples

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

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

function predicate( v ) {
    // Use the first letter of each element to define groups:
    return v[ 0 ] === 'b';
}

// 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 [...]

// Split the values:
var out = bifurcateValuesBy( x, predicate );
// returns [...]

console.log( out );
```

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