import isArrayLike from './_isArrayLike.js'; import values from './values.js'; import getLength from './_getLength.js'; import random from './random.js'; import toArray from './toArray.js'; // Sample **n** random values from a collection using the modern version of the // [Fisher-Yates shuffle](https://en.wikipedia.org/wiki/Fisher–Yates_shuffle). // If **n** is not specified, returns a single random element. // The internal `guard` argument allows it to work with `_.map`. export default function sample(obj, n, guard) { if (n == null || guard) { if (!isArrayLike(obj)) obj = values(obj); return obj[random(obj.length - 1)]; } var sample = toArray(obj); var length = getLength(sample); n = Math.max(Math.min(n, length), 0); var last = length - 1; for (var index = 0; index < n; index++) { var rand = random(index, last); var temp = sample[index]; sample[index] = sample[rand]; sample[rand] = temp; } return sample.slice(0, n); }