from math import *
def mmm(a,b):
sumofab=0.0
for i in range(len(a)):
temp=a[i]*b[i]
sumofab+=temp
return sumofab
def corrcoef(x,y):
n=len(x)
sum1=sum(x);sum2=sum(y)
sumofxy=mmm(x,y)
sumofx2 = sum([pow(i,2) for i in x])
sumofy2 = sum([pow(j,2) for j in y])
num=sumofxy-(float(sum1)*float(sum2)/n)
den=sqrt((sumofx2-float(sum1**2)/n)*(sumofy2-float(sum2**2)/n))
return num/den
a=[1,2,3,1]
b=[2,2,4,2]
cor=corrcoef(a,b)
print(cor)
