28 lines
779 B
Markdown
28 lines
779 B
Markdown
---
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title: Most frequent element in array
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tags: array
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author: chalarangelo
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cover: blog_images/clock.jpg
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firstSeen: 2020-01-03T15:32:46+02:00
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lastUpdated: 2020-09-15T16:28:04+03:00
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---
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Returns the most frequent element in an array.
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- Use `Array.prototype.reduce()` to map unique values to an object's keys, adding to existing keys every time the same value is encountered.
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- Use `Object.entries()` on the result in combination with `Array.prototype.reduce()` to get the most frequent value in the array.
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```js
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const mostFrequent = arr =>
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Object.entries(
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arr.reduce((a, v) => {
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a[v] = a[v] ? a[v] + 1 : 1;
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return a;
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}, {})
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).reduce((a, v) => (v[1] >= a[1] ? v : a), [null, 0])[0];
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```
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```js
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mostFrequent(['a', 'b', 'a', 'c', 'a', 'a', 'b']); // 'a'
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```
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