Re: [igraph] Transitivity

[Tamás Nepusz]

> Transitivity is the ratio of the triangles and the connected triples 
> in the graph

"The global [clustering] coefficient is the fraction of triplets or 2-paths 
(i.e., three nodes connected by two ties) that are closed by the presence of a 
tie between the first and the third node. It is formally defined as:

C = 3 x triangles / triplets"

according to http://arxiv.org/pdf/1006.0887v3.pdf. I think this the same as the 
definition on Wikipedia and in the Wasserman-Faust book.

In your graph, the number of 2-paths is 10: {021}, {023}, {032}, {123}, {203} 
and their reversed variants: {120}, {320}, {230}, {321}, {302}. 6 out of these 
are connected by a tie between the first and the third node: {023}, {032}, 
{203} and their reversed variants. Therefore, you have 6 / 10 = 0.6.

Cheers,
Tamas