31 lines
794 B
Markdown
31 lines
794 B
Markdown
---
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title: N random elements in array
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type: snippet
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language: javascript
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tags: [array,random]
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cover: peaches
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dateModified: 2020-10-22T20:24:30+03:00
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---
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Gets `n` random elements at unique keys from an array up to the size of the array.
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- Shuffle the array using the [Fisher-Yates algorithm](https://github.com/30-seconds/30-seconds-of-code#shuffle).
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- Use `Array.prototype.slice()` to get the first `n` elements.
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- Omit the second argument, `n`, to get only one element at random from the array.
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```js
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const sampleSize = ([...arr], n = 1) => {
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let m = arr.length;
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while (m) {
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const i = Math.floor(Math.random() * m--);
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[arr[m], arr[i]] = [arr[i], arr[m]];
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}
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return arr.slice(0, n);
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};
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```
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```js
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sampleSize([1, 2, 3], 2); // [3, 1]
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sampleSize([1, 2, 3], 4); // [2, 3, 1]
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```
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