Re: [igraph] read.graph query

[Tamás Nepusz]

> When I write out and then read in a graph, it's average path length 
> changes - code and output below. Anyone know why this is happening?

Yes.

Option #1) You have isolated vertices in your graph. These are lost when you 
save it into edge list format, therefore the average path length changes when 
you load the graph back.

Option #2) Your original graph is undirected and the graph becomes directed 
when you load it back (or vice versa). The edge list format does not store 
whether your graph is directed or not, hence you have to provide this 
information when you load a graph from the edge list format. This does not 
change the transitivity because edge directions are ignored when calculating 
the transitivity, but obviously it changes the average path length.

Best,
Tamas