@stdlib/array-base-bifurcate-indices-by v0.2.1

bifurcateIndicesBy

Split element indices into two groups according to a predicate function.

Installation

npm install @stdlib/array-base-bifurcate-indices-by

Usage

var bifurcateIndicesBy = require( '@stdlib/array-base-bifurcate-indices-by' );

bifurcateIndicesBy( x, predicate[, thisArg] )

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

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

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

var out = bifurcateIndicesBy( x, predicate );
// returns [ [ 0, 1, 3 ], [ 2 ] ]

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.

function predicate( v ) {
    this.count += 1;
    return v[ 0 ] === 'b';
}

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

var context = {
    'count': 0
};
var out = bifurcateIndicesBy( x, predicate, context );
// returns [ [ 0, 1, 3 ], [ 2 ] ]

var cnt = context.count;
// returns 4

Examples

var discreteUniform = require( '@stdlib/random-array-discrete-uniform' );
var take = require( '@stdlib/array-base-take-indexed' );
var bifurcateIndicesBy = require( '@stdlib/array-base-bifurcate-indices-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 = bifurcateIndicesBy( x, predicate );
// returns [...]

console.log( out );

Notice

This package is part of 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, see the main project repository.

Community

License

See LICENSE.

Copyright

Copyright © 2016-2024. The Stdlib Authors.