Property maps / Graph library

Hi, The examples in libs/graph/example have property_map like vertex_name that associates a 'vertex -> user-defined name' (usually a std::string). Without having to use an external std::map, is there any way to create a property_map that provides the reverse association 'user-defined name -> vertex', so that I can retreive the vertex based on the user-defined name and without iterating thru each vertex. Thanks Rajesh