余弦相似度

yingl · yingl · commit b2c14b2db11f · 2016-08-04T14:15:22.000+08:00
diff --git a/cosine_similarity.py b/cosine_similarity.py
@@ -0,0 +1,18 @@
+# -*- coding: utf-8 -*-
+
+class Solution:
+    """
+    @param A: An integer array.
+    @param B: An integer array.
+    @return: Cosine similarity.
+    """
+    def cosineSimilarity(self, A, B):
+        # write your code here
+        sqr_a, sqr_b, sum_a_dot_b = 0, 0, 0
+        for i in xrange(len(A)):
+            sqr_a += A[i] * A[i]
+            sqr_b += B[i] * B[i]
+            sum_a_dot_b += A[i] * B[i]
+        if sqr_a == 0 or sqr_b == 0:
+            return 2.0
+        return sum_a_dot_b / math.sqrt(sqr_a * sqr_b)
