diff --git a/kdtree/kdtree.go b/kdtree/kdtree.go
index a88a4ab..2797719 100644
--- a/kdtree/kdtree.go
+++ b/kdtree/kdtree.go
@@ -111,29 +111,31 @@ func (t *Tree) buildHandle(data []int, featureIndex int) *node {
 	return n
 }
 
-// Search return []int contained k nearest neighbor from
-// specific distance function.
-func (t *Tree) Search(k int, disType pairwise.PairwiseDistanceFunc, target []float64) ([]int, error) {
+// Search return srcRowNo([]int) and length([]float64) contained
+// k nearest neighbors from specific distance function.
+func (t *Tree) Search(k int, disType pairwise.PairwiseDistanceFunc, target []float64) ([]int, []float64, error) {
 	if k > len(t.data) {
-		return []int{}, errors.New("k is largerer than amount of trainData")
+		return []int{}, []float64{}, errors.New("k is largerer than amount of trainData")
 	}
 
 	if len(target) != len(t.data[0]) {
-		return []int{}, errors.New("amount of features is not equal")
+		return []int{}, []float64{}, errors.New("amount of features is not equal")
 	}
 
 	h := newHeap()
 	t.searchHandle(k, disType, target, h, t.firstDiv)
 
-	out := make([]int, k)
+	srcRowNo := make([]int, k)
+	length := make([]float64, k)
 	i := k - 1
 	for h.size() != 0 {
-		out[i] = h.maximum().srcRowNo
+		srcRowNo[i] = h.maximum().srcRowNo
+		length[i] = h.maximum().length
 		i--
 		h.extractMax()
 	}
 
-	return out, nil
+	return srcRowNo, length, nil
 }
 
 func (t *Tree) searchHandle(k int, disType pairwise.PairwiseDistanceFunc, target []float64, h *heap, n *node) {
diff --git a/kdtree/kdtree_test.go b/kdtree/kdtree_test.go
index c8f80ba..8d2a565 100644
--- a/kdtree/kdtree_test.go
+++ b/kdtree/kdtree_test.go
@@ -16,7 +16,7 @@ func TestKdtree(t *testing.T) {
 		euclidean := pairwise.NewEuclidean()
 
 		Convey("When k is 3 with euclidean", func() {
-			result, _ := kd.Search(3, euclidean, []float64{7, 3})
+			result, _, _ := kd.Search(3, euclidean, []float64{7, 3})
 
 			Convey("The result[0] should be 4", func() {
 				So(result[0], ShouldEqual, 4)
@@ -30,7 +30,7 @@ func TestKdtree(t *testing.T) {
 		})
 
 		Convey("When k is 2 with euclidean", func() {
-			result, _ := kd.Search(2, euclidean, []float64{7, 3})
+			result, _, _ := kd.Search(2, euclidean, []float64{7, 3})
 
 			Convey("The result[0] should be 4", func() {
 				So(result[0], ShouldEqual, 4)