Refactor: grouping parent and their space by including array.

app/helpers/graph_helper.rb

@@ -2,4 +2,9 @@ module GraphHelper
   def join_with_space(ary)
     ary.collect{|r|r.name}.join(" ") unless ary.nil?
   end
+
+  def parents_zip_spaces(parents, parent_spaces)
+    ids = parents.map { |p| p.id }
+    ids.zip(parent_spaces)
+  end
 end