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)))
+}

backend/utils/cosimi_test.go

@@ -0,0 +1,19 @@
+package utils
+
+import (
+	"math"
+	"testing"
+)
+
+func TestSimilarity(t *testing.T) {
+	r := Similarity([]uint8{1, 2, 3}, []uint8{1, 3, 4})
+	t.Log(r)
+	if math.Abs(r-0.9958705948858224) > 1e-6 {
+		t.Fail()
+	}
+	r = Similarity([]uint8{3, 2, 1}, []uint8{1, 3, 4})
+	t.Log(r)
+	if math.Abs(r-0.6813851438692469) > 1e-6 {
+		t.Fail()
+	}
+}