Hi Tiago, I'm experimenting some problems with the remove_parallel_edges function. It seems that some edges are removed randomly. I attach some reproducible code to test. Let's suppose the following dot graph file: graph G{ 1--2 2--1 1--3 3--1 2--3 3--2 } It is basically an undirected graph with a triangle shape with parallel edges. The following code loads the graph, removes parallel edges and calculate clustering coefficient. I repeat it ten times. for i in range(0,10): aux = gt.load_graph("/tmp/sampleGraph.dot",format="dot") gt.remove_parallel_edges (aux) clust=gt.local_clustering (aux) gt.vertex_average (aux,clust) This operation is supposed to generate a tuple (1.0, 0.0), the problem is that randomly the generated output is wrong. For example: Out[111]: (1.0, 0.0) Out[111]: (1.0, 0.0) Out[111]: (1.0, 0.0) Out[111]: (1.0, 0.0) Out[111]: (0.0, 0.0) Out[111]: (1.0, 0.0) Out[111]: (1.0, 0.0) Out[111]: (1.0, 0.0) Out[111]: (1.0, 0.0) Out[111]: (1.0, 0.0) I have plotted the graph and I have found, that sometimes one edge is completely removed modifying the final result. I attach my show_config output. gt.show_config () version: 2.2.5 (commit 3ba24072, Sun Feb 21 00:46:41 2010 +0100) gcc version: 4.4.1 compilation flags: -I/usr/include/python2.6 -I/usr/include -I/usr/lib/python2.6/dist-packages/numpy/core/include/numpy -I/usr/lib/python2.6/dist-packages/scipy -O3 -Wall -ftemplate-depth-150 -Wno-deprecated -O99 -fvisibility=default -fvisibility-inlines-hidden -fopenmp -Wl,-Bsymbolic-functions -L/usr/lib/python2.6 -lpython2.6 install prefix: /usr python dir: /usr/lib/python2.6/dist-packages graph filtering: True openmp: True uname: Linux host 2.6.31-22-generic #60-Ubuntu SMP Thu May 27 02:41:03 UTC 2010 x86_64 Kind regards, Juan ================================ Juan Manuel Tirado 2.2.C02.B +34 91 624 6260 Computer Department Computer Architecture Group http://www.arcos.inf.uc3m.es University Carlos III of Madrid http://www.uc3m.es ================================