30 lines
671 B
Markdown
30 lines
671 B
Markdown
---
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title: weightedAverage
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tags: math,intermediate
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firstSeen: 2020-10-04T00:38:33+03:00
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lastUpdated: 2020-11-03T21:46:13+02:00
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---
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Calculates the weighted average of two or more numbers.
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- Use `Array.prototype.reduce()` to create the weighted sum of the values and the sum of the weights.
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- Divide them with each other to get the weighted average.
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```js
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const weightedAverage = (nums, weights) => {
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const [sum, weightSum] = weights.reduce(
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(acc, w, i) => {
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acc[0] = acc[0] + nums[i] * w;
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acc[1] = acc[1] + w;
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return acc;
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},
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[0, 0]
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);
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return sum / weightSum;
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};
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```
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```js
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weightedAverage([1, 2, 3], [0.6, 0.2, 0.3]); // 1.72727
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```
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