Find Correlation Coefficient in C++

In this tutorial, we will be discussing a program to find correlation coefficient.

For this we will be provided with two arrays. Our task is to find the correlation coefficient denoting the strength of the relation between the given values.

Example

 Live Demo

#include<bits/stdc++.h>
using namespace std;
//function returning correlation coefficient
float find_coefficient(int X[], int Y[], int n){
   int sum_X = 0, sum_Y = 0, sum_XY = 0;
   int squareSum_X = 0, squareSum_Y = 0;
   for (int i = 0; i < n; i++){
      sum_X = sum_X + X[i];
      sum_Y = sum_Y + Y[i];
      sum_XY = sum_XY + X[i] * Y[i];
      squareSum_X = squareSum_X + X[i] * X[i];
      squareSum_Y = squareSum_Y + Y[i] * Y[i];
   }
   float corr = (float)(n * sum_XY - sum_X * sum_Y) / sqrt((n * squareSum_X - sum_X * sum_X) * (n * squareSum_Y - sum_Y * sum_Y));
   return corr;
}
int main(){
   int X[] = {15, 18, 21, 24, 27};
   int Y[] = {25, 25, 27, 31, 32};
   int n = sizeof(X)/sizeof(X[0]);
   cout<<find_coefficient(X, Y, n);
   return 0;
}

Output

0.953463