def cos_sim(data,usr1,usr2):
fenzi=0
for i in range(len(data[usr1])):
a=data[usr1][i]*data[usr2][i]
fenzi+=a
fenmu1=0
for i in data[usr2]:
fenmu1+=i*i
fenmu2=0
for i in data[usr1]:
fenmu2+=i*i
from math import sqrt
cos_s=fenzi/sqrt(fenmu1*fenmu2)
return cos_s
网友评论