Hello, I'm using a cvsreader to parse a very big file and create an undirected graph accordingly. The file can contain duplicated edges (i.e. A B in one row, B A in another one), so I'm checking if g.edge(v1,v2)==None: e = g.add_edge(v1,v2) in order to discard them (v1 and v2 are vertices created from what it's read from the file). However the graph contains a lot of edges (few millions) and vertices (many thousands), with a potentially high degree for the vertices, and it takes a lot to process the data. As far as I read in the soruce code, the Graph.edge() method checks all the outgoing edges of the source node, but even if I check which node has the highest degree, it takes a lot of time to build the graph. Is there any other way to remove the duplicated edges? Maybe an edge filter based on some lambda wizardry? Thanks in advance, Giuseppe -- Researcher at University of Bologna, Italy