26 lines
605 B
Markdown
26 lines
605 B
Markdown
---
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title: Percentile of matches
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type: snippet
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tags: [math]
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cover: red-berries
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dateModified: 2020-10-22T20:24:04+03:00
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---
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Calculates the percentage of numbers in the given array that are less or equal to the given value.
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- Use `Array.prototype.reduce()` to calculate how many numbers are below the value and how many are the same value and apply the percentile formula.
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```js
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const percentile = (arr, val) =>
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(100 *
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arr.reduce(
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(acc, v) => acc + (v < val ? 1 : 0) + (v === val ? 0.5 : 0),
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0
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)) /
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arr.length;
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```
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```js
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percentile([1, 2, 3, 4, 5, 6, 7, 8, 9, 10], 6); // 55
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```
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