def _property_name_to_values(entities):
 property_name_to_values = {}
 for entity in entities:
  for (property_name, value) in entity.iteritems():
   property_name_to_values.setdefault(property_name, []).append(value)
 return property_name_to_values

def _property_name_to_values ( entities ) : property_name_to_values = { } for entity in entities : for ( property_name , value ) in entity . iteritems ( ) : property_name_to_values . setdefault ( property_name , [ ] ) . append ( value ) return property_name_to_values
returns a a mapping of entity property names to a list of their values .