question: public TIntIntMap buildOneDistanceTable ( int stop ) { int originVertex = streetVertexForStop . get ( stop ) ; if ( originVertex == - 1 ) { LOG . warn ( "Stop {} has not been linked to the street network, cannot build a distance table for it." , stop ) ; return null ; } StreetRouter router = new StreetRouter ( parentNetwork . streetLayer ) ; router . distanceLimitMeters = DISTANCE_TABLE_SIZE_METERS ; router . dominanceVariable = StreetRouter . State . RoutingVariable . DISTANCE_MILLIMETERS ; router . setOrigin ( originVertex ) ; router . route ( ) ; return router . getReachedVertices ( ) ; }
target:  Perform a single on-street search from the specified transit stop. Return the distance in millimeters to every reached street vertex.