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## Re: [igraph] Clustering coefficient vs. transitivity

**From**: |
Tamas Nepusz |

**Subject**: |
Re: [igraph] Clustering coefficient vs. transitivity |

**Date**: |
Tue, 6 Jul 2010 10:17:17 +0100 |

Dear Jonathan,
>* I'm using igraph 0.6 via the Python interface. From some test cases I*
>* get the impression, that the function transitivity_undirected actually*
>* gives the mean value of transitivity_local_undirected. Is this*
>* correct?*
No; transitivity_avglocal_undirected is the mean value of
transitivity_local_undirected. transitivity_undirected is indeed according to
Eq.~(2.8) in the Boccaletti review; that is, 3 x (# of triangles) / (# of
connected triplets):
>*>> g = Graph.GRG(100, 0.2)*
>*>> g.transitivity_undirected()*
0.63212
>*>> g.transitivity_avglocal_undirected()*
0.64516
>*>> sum(g.transitivity_local_undirected())/g.vcount()*
0.64516
Also note that there are two possible ways to define
transitivity_local_undirected(), depending on how vertices with degree less
than two are treated. igraph can either treat them as havng zero local
transitivity, or return NaN (not a number).
--
Tamas