mean-square-error.md

Mean Square Error ^{5 Kyu}

^{LINK TO THE KATA - ARRAYS MATHEMATICS ALGORITHMS}

Description

Complete the function that

• accepts two integer arrays of equal length
• compares the value each member in one array to the corresponding member in the other
• squares the absolute value difference between those two values
• and returns the average of those squared absolute value difference between each member pair.

Examples

[1, 2, 3], [4, 5, 6]              -->   9   because (9 + 9 + 9) / 3
[10, 20, 10, 2], [10, 25, 5, -2]  -->  16.5 because (0 + 25 + 25 + 16) / 4
[-1, 0], [0, -1]                  -->   1   because (1 + 1) / 2

Solution

const getDifferenceBetweenTwoNumbersSquared = (num1, num2) => {
  return Math.pow(Math.abs(num1 - num2), 2)
}

const solution = (firstArray, secondArray) => {
  return (
    firstArray.reduce((acc, cur, ind) => {
      return acc + getDifferenceBetweenTwoNumbersSquared(cur, secondArray[ind])
    }, 0) / firstArray.length
  )
}