Rename should return a pandas DF, not a numpy array
@@ -195,7 +195,7 @@ class Rename(Transformation):
''' Rename happens automatically in the base class, so all we need to
do is unset the original variable in the collection. '''
self.collection.variables.pop(var.name)
- return var.values.values
+ return var.values
class Replace(Transformation):
