diff --git a/src/pkg/container/vector/Makefile b/src/pkg/container/vector/Makefile
index f664b43f94..1eb310c6d8 100644
--- a/src/pkg/container/vector/Makefile
+++ b/src/pkg/container/vector/Makefile
@@ -42,7 +42,7 @@ generate: vector.go vector_test.go
 	| gofmt -r='make_vector -> make_vectorInt'\
 	| gofmt -r='TestInsertVector -> TestIntInsertVector'\
 	| gofmt -r='TestDo -> TestIntDo'\
-	| gofmt -r='TestVectorData -> TestIntVectorData'\
+	| gofmt -r='TestVectorCopy -> TestIntVectorCopy'\
 	| gofmt -r='interface{} -> int'\
 	> intvector_test.go\
 	
@@ -64,6 +64,6 @@ generate: vector.go vector_test.go
 	| gofmt -r='make_vector -> make_vectorStr'\
 	| gofmt -r='TestInsertVector -> TestStrInsertVector'\
 	| gofmt -r='TestDo -> TestStrDo'\
-	| gofmt -r='TestVectorData -> TestStrVectorData'\
+	| gofmt -r='TestVectorCopy -> TestStrVectorCopy'\
 	| gofmt -r='interface{} -> string'\
 	> stringvector_test.go
diff --git a/src/pkg/container/vector/intvector.go b/src/pkg/container/vector/intvector.go
index 5f4d6fa3d7..5ad9e294b7 100644
--- a/src/pkg/container/vector/intvector.go
+++ b/src/pkg/container/vector/intvector.go
@@ -104,8 +104,8 @@ func (p *IntVector) Set(i int, x int) { (*p)[i] = x }
 func (p *IntVector) Last() int { return (*p)[len(*p)-1] }
 
 
-// Data returns all the elements as a slice.
-func (p *IntVector) Data() []int {
+// Copy makes a copy of the vector and returns it.
+func (p *IntVector) Copy() IntVector {
 	arr := make(IntVector, len(*p))
 	copy(arr, *p)
 	return arr
diff --git a/src/pkg/container/vector/intvector_test.go b/src/pkg/container/vector/intvector_test.go
index 2f853ebfac..fcc7403b36 100644
--- a/src/pkg/container/vector/intvector_test.go
+++ b/src/pkg/container/vector/intvector_test.go
@@ -326,14 +326,14 @@ func TestIntDo(t *testing.T) {
 }
 
 
-func TestIntVectorData(t *testing.T) {
-	// verify Data() returns a slice of a copy, not a slice of the original vector
+func TestIntVectorCopy(t *testing.T) {
+	// verify Copy() returns a copy, not simply a slice of the original vector
 	const Len = 10
 	var src IntVector
 	for i := 0; i < Len; i++ {
 		src.Push(int2IntValue(i * i))
 	}
-	dest := src.Data()
+	dest := src.Copy()
 	for i := 0; i < Len; i++ {
 		src[i] = int2IntValue(-1)
 		v := elem2IntValue(dest[i])
diff --git a/src/pkg/container/vector/stringvector.go b/src/pkg/container/vector/stringvector.go
index a9b727a908..852685f5a1 100644
--- a/src/pkg/container/vector/stringvector.go
+++ b/src/pkg/container/vector/stringvector.go
@@ -104,8 +104,8 @@ func (p *StringVector) Set(i int, x string) { (*p)[i] = x }
 func (p *StringVector) Last() string { return (*p)[len(*p)-1] }
 
 
-// Data returns all the elements as a slice.
-func (p *StringVector) Data() []string {
+// Copy makes a copy of the vector and returns it.
+func (p *StringVector) Copy() StringVector {
 	arr := make(StringVector, len(*p))
 	copy(arr, *p)
 	return arr
diff --git a/src/pkg/container/vector/stringvector_test.go b/src/pkg/container/vector/stringvector_test.go
index 1c05145a24..2f3f082bdc 100644
--- a/src/pkg/container/vector/stringvector_test.go
+++ b/src/pkg/container/vector/stringvector_test.go
@@ -326,14 +326,14 @@ func TestStrDo(t *testing.T) {
 }
 
 
-func TestStrVectorData(t *testing.T) {
-	// verify Data() returns a slice of a copy, not a slice of the original vector
+func TestStrVectorCopy(t *testing.T) {
+	// verify Copy() returns a copy, not simply a slice of the original vector
 	const Len = 10
 	var src StringVector
 	for i := 0; i < Len; i++ {
 		src.Push(int2StrValue(i * i))
 	}
-	dest := src.Data()
+	dest := src.Copy()
 	for i := 0; i < Len; i++ {
 		src[i] = int2StrValue(-1)
 		v := elem2StrValue(dest[i])
diff --git a/src/pkg/container/vector/vector.go b/src/pkg/container/vector/vector.go
index f219cdcaaf..f43e4d23ca 100644
--- a/src/pkg/container/vector/vector.go
+++ b/src/pkg/container/vector/vector.go
@@ -104,8 +104,8 @@ func (p *Vector) Set(i int, x interface{}) { (*p)[i] = x }
 func (p *Vector) Last() interface{} { return (*p)[len(*p)-1] }
 
 
-// Data returns all the elements as a slice.
-func (p *Vector) Data() []interface{} {
+// Copy makes a copy of the vector and returns it.
+func (p *Vector) Copy() Vector {
 	arr := make(Vector, len(*p))
 	copy(arr, *p)
 	return arr
diff --git a/src/pkg/container/vector/vector_test.go b/src/pkg/container/vector/vector_test.go
index ba15398c28..986dff2da7 100644
--- a/src/pkg/container/vector/vector_test.go
+++ b/src/pkg/container/vector/vector_test.go
@@ -326,14 +326,14 @@ func TestDo(t *testing.T) {
 }
 
 
-func TestVectorData(t *testing.T) {
-	// verify Data() returns a slice of a copy, not a slice of the original vector
+func TestVectorCopy(t *testing.T) {
+	// verify Copy() returns a copy, not simply a slice of the original vector
 	const Len = 10
 	var src Vector
 	for i := 0; i < Len; i++ {
 		src.Push(int2Value(i * i))
 	}
-	dest := src.Data()
+	dest := src.Copy()
 	for i := 0; i < Len; i++ {
 		src[i] = int2Value(-1)
 		v := elem2Value(dest[i])
diff --git a/src/pkg/exp/iterable/iterable.go b/src/pkg/exp/iterable/iterable.go
index aefff94272..85e5f38b0e 100644
--- a/src/pkg/exp/iterable/iterable.go
+++ b/src/pkg/exp/iterable/iterable.go
@@ -39,11 +39,11 @@ func Any(iter Iterable, f func(interface{}) bool) bool {
 
 // Data returns a slice containing the elements of iter.
 func Data(iter Iterable) []interface{} {
-	vec := new(vector.Vector)
+	var v vector.Vector
 	for e := range iter.Iter() {
-		vec.Push(e)
+		v.Push(e)
 	}
-	return vec.Data()
+	return v
 }
 
 // filteredIterable is a struct that implements Iterable with each element
diff --git a/src/pkg/exp/iterable/iterable_test.go b/src/pkg/exp/iterable/iterable_test.go
index 1d60d4b910..26a2eecc45 100644
--- a/src/pkg/exp/iterable/iterable_test.go
+++ b/src/pkg/exp/iterable/iterable_test.go
@@ -371,7 +371,7 @@ func TestGroupBy(t *testing.T) {
 	for x := range GroupBy(elevenToTwenty, intkey{}).Iter() {
 		out.Push(x.(Group).Key)
 	}
-	assertArraysAreEqual(t, out.Data(), elevenToTwenty)
+	assertArraysAreEqual(t, out, elevenToTwenty)
 }
 
 func TestUnique(t *testing.T) {