28 lines
978 B
JavaScript
28 lines
978 B
JavaScript
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);
|
||
}
|