27 lines
699 B
Markdown
27 lines
699 B
Markdown
---
|
|
title: sampleSize
|
|
tags: array,random,intermediate
|
|
---
|
|
|
|
Gets `n` random elements at unique keys from an array up to the size of the array.
|
|
|
|
- Shuffle the array using the [Fisher-Yates algorithm](https://github.com/30-seconds/30-seconds-of-code#shuffle).
|
|
- Use `Array.prototype.slice()` to get the first `n` elements.
|
|
- Omit the second argument, `n`, to get only one element at random from the array.
|
|
|
|
```js
|
|
const sampleSize = ([...arr], n = 1) => {
|
|
let m = arr.length;
|
|
while (m) {
|
|
const i = Math.floor(Math.random() * m--);
|
|
[arr[m], arr[i]] = [arr[i], arr[m]];
|
|
}
|
|
return arr.slice(0, n);
|
|
};
|
|
```
|
|
|
|
```js
|
|
sampleSize([1, 2, 3], 2); // [3, 1]
|
|
sampleSize([1, 2, 3], 4); // [2, 3, 1]
|
|
```
|