> ... this is a crappy solution that's underusing Python. Please > enlighten me of a better way! > > - Fencer
One thing that springs to mind is using the dict method .setdefault <untested> for dkey, vallist in old_dict.iteritems(): for val in vallist: new_dict.setdefault(val, set()).add(dkey) </untested> -- http://mail.python.org/mailman/listinfo/python-list