add cosine similarity & 完善 PaperType

backend/utils/cosimi.go

@@ -0,0 +1,19 @@
+// edit from https://github.com/kabychow/go-cosinesimilarity
+
+package utils
+
+import "math"
+
+// Similarity len(x) must eq len(y)
+func Similarity(x, y []uint8) float64 {
+	var sum, s1, s2 uint64
+	for i := 0; i < len(x); i++ {
+		sum += uint64(x[i]) * uint64(y[i])
+		s1 += uint64(x[i]) * uint64(x[i])
+		s2 += uint64(y[i]) * uint64(y[i])
+	}
+	if s1 == 0 || s2 == 0 {
+		return 0.0
+	}
+	return float64(sum) / (math.Sqrt(float64(s1)) * math.Sqrt(float64(s2)))
+}