28 lines
983 B
JavaScript
28 lines
983 B
JavaScript
|
define(['./_isArrayLike', './values', './_getLength', './random', './toArray'], function (_isArrayLike, values, _getLength, random, toArray) {
|
|||
|
|
|
|||
|
|
// 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`.
|
|||
|
|
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);
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
return sample;
|
|||
|
|
|
|||
|
|
});
|