Use pytable's createparents flag to avoid having to create group

structure manually.

nilmdb/nilmdb.py

@@ -291,16 +291,6 @@ class NilmDB(object):
         if group == '':
             raise ValueError("invalid path")
 
-        # Make the group structure, one element at a time
-        group_path = group.lstrip('/').split("/")
-        for i in range(len(group_path)):
-            parent = "/" + "/".join(group_path[0:i])
-            child = group_path[i]
-            try:
-                self.h5file.createGroup(parent, child)
-            except tables.NodeError:
-                pass
-
         # Get description
         try:
             desc = nilmdb.layout.get_named(layout_name).description()
@@ -314,7 +304,8 @@ class NilmDB(object):
         # Create the table
         table = self.h5file.createTable(group, node,
                                         description = desc,
-                                        expectedrows = exp_rows)
+                                        expectedrows = exp_rows,
+                                        createparents = True)
 
         # Insert into SQL database once the PyTables is happy
         with self.con as con: