From 4fc0ed0477cf552dff32b91bd648b0998aa34eec Mon Sep 17 00:00:00 2001
From: Bert Chang <jrweizhang@gmail.com>
Date: Fri, 2 May 2014 23:49:06 +0800
Subject: [PATCH] Add euclidean distance test.

---
 metrics/pairwise/euclidean.go      |  7 ++++++-
 metrics/pairwise/euclidean_test.go | 29 +++++++++++++++++++++--------
 2 files changed, 27 insertions(+), 9 deletions(-)

diff --git a/metrics/pairwise/euclidean.go b/metrics/pairwise/euclidean.go
index 696e93f..ff96a75 100644
--- a/metrics/pairwise/euclidean.go
+++ b/metrics/pairwise/euclidean.go
@@ -23,7 +23,12 @@ func (self *Euclidean) InnerProduct(vectorX *mat.DenseMatrix, vectorY *mat.Dense
 // We may need to create Metrics / Vector interface for this
 func (self *Euclidean) Distance(vectorX *mat.DenseMatrix, vectorY *mat.DenseMatrix) (float64, error) {
 	difference, err := vectorY.MinusDense(vectorX)
+
+	if err != nil {
+		return 0, err
+	}
+
 	result := self.InnerProduct(difference, difference)
 
-	return math.Sqrt(result), err
+	return math.Sqrt(result), nil
 }
diff --git a/metrics/pairwise/euclidean_test.go b/metrics/pairwise/euclidean_test.go
index 08c0d9f..14827af 100644
--- a/metrics/pairwise/euclidean_test.go
+++ b/metrics/pairwise/euclidean_test.go
@@ -7,27 +7,40 @@ import (
 	mat "github.com/skelterjohn/go.matrix"
 )
 
-func TestEuclideanInnerProduct(t *testing.T) {
+func TestEuclidean(t *testing.T) {
 	euclidean := NewEuclidean()
 
 	Convey("Given two vectors", t, func() {
 		vectorX := mat.MakeDenseMatrix([]float64{1, 2, 3}, 3, 1)
-		vectorY := mat.MakeDenseMatrix([]float64{3, 4, 5}, 3, 1)
+		vectorY := mat.MakeDenseMatrix([]float64{2, 4, 5}, 3, 1)
 
 		Convey("When doing inner product", func() {
 			result := euclidean.InnerProduct(vectorX, vectorY)
 
-			Convey("The result should be 26", func() {
-				So(result, ShouldEqual, 26)
+			Convey("The result should be 25", func() {
+				So(result, ShouldEqual, 25)
+			})
+
+			Convey("When dimension not match", func() {
+				vectorZ := mat.MakeDenseMatrix([]float64{3, 4, 5}, 1, 3)
+
+				Convey("It should panic with Dimension mismatch", func() {
+					So(func() { euclidean.InnerProduct(vectorX, vectorZ) }, ShouldPanicWith, "Dimension mismatch")
+				})
+
 			})
 
 		})
 
-		Convey("When dimension not match", func() {
-			vectorY = mat.MakeDenseMatrix([]float64{3, 4, 5}, 1, 3)
+		Convey("When calculating distance", func() {
+			result, err := euclidean.Distance(vectorX, vectorY)
 
-			Convey("It should panic with Dimension mismatch", func() {
-				So(func() { euclidean.InnerProduct(vectorX, vectorY) }, ShouldPanicWith, "Dimension mismatch")
+			Convey("The err should be nil", func() {
+				So(err, ShouldBeNil)
+			})
+
+			Convey("The result should be 3", func() {
+				So(result, ShouldEqual, 3)
 			})
 
 		})