setup-maven-cached/node_modules/underscore/modules/sample.js

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2022-06-28 16:39:30 +08:00
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/FisherYates_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);
}