#!/usr/bin/pythonfrom math import sqrtdef euclidean(v1, v2): length = min(len(v1), len(v2)) if length == 0: return 0 d = 0 for i in range(length): d += pow((v1[i] - v2[i]), 2) #return sqrt(d) return 1 / float(1+d)def cosine(v1, v2): length = min(len(v1), len(v2)) if length == 0: return 0 dp = 0 #dot product m1 = 0 #modulus of v1 m2 = 0 #modulus of v2 for i in range(length): dp += v1[i] * v2[i] m1 += v1[i] * v1[i] m2 += v2[i] * v2[i] if m1 == 0 or m2 == 0: return 0 distance = dp / (sqrt(m1) * sqrt(m2)) return distancedef pearson(v1, v2): length = min(len(v1), len(v2)) if length == 0: return 0 #e of v1 v2 e1 = 0 e2 = 0 for i in range(length): e1 += v1[i] e2 += v2[i] e1 /= float(length) e2 /= float(length) cov = 0 #cov of v1 v2 d1 = 0 #variance of v2 d2 = 0 #variance of v2 for i in range(length): diff1 = v1[i] - e1 diff2 = v2[i] - e2 cov += diff1 * diff2 d1 += diff1 * diff1 d2 += diff2 * diff2 cov /= float(length) d1 /= float(length) d2 /= float(length) if d1 == 0 or d2 == 0: return 0 return cov / sqrt(d1 * d2)
