“nodelist” is an interchange structure of nodes from a spatial network into an “igraph” object. It is a two-column data frame, of which each row is designed as [NodeID,coordinate(X,Y)].
Both “nodelist” and “edgelist” are interchange structures of nodes and edges extracted from a spatial network in a “SpatialLines” or “SpatialLinesDataFrame” object. They are always concerned together, and returned by the function readshpnw as initial results for the following steps.