Random-from-collection NPM

`random-from-collection`

Get a random set of n distinct values from a standard collection (i.e. Map, Set).

Why?

Types like Map and Set do not allow for access by index, so pulling a random set of values requires using an iterator. This package handles that scenario.

API

This package exports a single function that accepts a collection and a number of values to select. The collection can be any object that provides a size or length property/getter, and a keys() method that returns an iterator. In particular, it is useful for built-in types like Map and Set.

It can be used on Arrays, but wouldn't really be very efficient, as Array allows for direct access by index so it is much faster to use a package like array-shuffle instead.

Usage

const randomFromCollection = require('random-from-collection');

const mySet = new Set([1, 2, 3, 4, 5, 6, 7, 8, 9]);
const setResults = randomFromCollection(mySet, 5);
/*
[1, 4, 6, 8, 9]
*/

const myMap = new Map([
  ['a', 'A'],
  ['b', 'B'],
  ['c', 'C']
]);
const mapResults = randomFromCollection(myMap, 2);
/*
['a', 'c']
*/

// Need Map values?
const mapResultsValues = mapResults.map(k => myMap.get(k));
/*
['A', 'C']
*/