Re: [igraph] graph.edgelist() behavior

[Tamas Nepusz]

> and give the command graph.edgelist(E, directed = FALSE), I instead
> get 8 edges. The adjacency matrix for this graph instead has zeros and
> twos, which means that 1 2 and 2 1 were counted separately and they're
> NOT the same.
That's the expected behaviour (and I hope you intended to write 6  
edges instead of 8, otherwise it is really a bug :)). Consider this as  
follows: if you have an undirected graph, then adding an edge from  
vertex A to B "automatically creates" its counterpart from vertex B to  
A. After that, adding an edge from B to A creates _another_ edge along  
with its counterpart. You simply get multiple edges between A and B.  
If you want to get rid of multiple edges, you can use simplify() on  
your graph after creation -- this removes multiple and loop edges.

--
Tamas