[igraph] igraph - problem at summary function: number of nodes does not match

[Csaba Ragany]

Dear igraph community,

I'm new to igraph, I use it with Python (Anaconda) 2.7 (x64).

My problem is the following:
I created a small test graph given with edgelist: it has 8 nodes and 9 edges. The summary(my_graph) function returns with this:
IGRAPH U--- 8 9 --

It' OK.

After that I read the Stanford DBLP collaboration network graph that is available here:
http://snap.stanford.edu/data/com-DBLP.html

It has 317080 nodes and 1049866 edges. But the summary(my_graph) function returns with this:
IGRAPH U--- 425957 1049865 --

Can anyone explain why the number of nodes is 425957 instead 317080?

If I load this graph into Gephi, the number of nodes and edges are correctly determined.

Thank you for any help!

ragesz