I would recommend posting the question on https://igraph.discourse.group/ as that forum is meant to replace this mailing list, and provides a nicer discussion environment.
On Sun, 29 Mar 2020 at 15:08, serafim loukas <seral...@hotmail.com> wrote: > Just to add that I just found the *python* version of BCT (the Matlab > toolbox that I used to benchmark igraph). > > Using this: > https://github.com/aestrivex/bctpy/blob/f9526a693a9af57051762442d8490dcdf2ebf4e3/bct/algorithms/modularity.py#L71, > again I get approx. 0.1466 that matches the Matlab based results but is far > from the python output (Q). > > Makis > > On 29 Mar 2020, at 14:56, serafim loukas <seral...@hotmail.com> wrote: > > Hi igraph community, > > > I have a graph and I want to estimate the modularity (Q) based on the > Louvain split of the graph. > > In python I used igraph and to compare, I also estimated Q in Matlab. > Based on igraph, the Q is negative (weird) whereas the Q based on the > Matlab estimation is possitive. > > I would expect differences in the values but not by so far (+ shows > modularity, - shows anti-modularity). > Any idea why this happens? > > Makis > > ——————————— > > My code and data: > > > PYTHON > > ``` > import numpy as np > import scipy.io > from igraph import * > > A = scipy.io.loadmat('A.mat')['A'] > > graph = Graph.Weighted_Adjacency(A.tolist(), mode=ADJ_UNDIRECTED, > attr="weight", loops=False) > Louvain = graph.community_multilevel(weights=graph.es['weight'], > return_levels=False) > Q = graph.modularity(Louvain) > print(Q) > > -0.001847596203445795 > ``` > > > MATLAB (https://sites.google.com/site/bctnet/measures/list) > using community_louvain.m: Louvain community detection algorithm > > ``` > clear all > load('A.mat') > [M,Q]=community_louvain(A); > > Q = > > 0.1466 > ``` > > <A.mat>_______________________________________________ > igraph-help mailing list > igraph-help@nongnu.org > https://lists.nongnu.org/mailman/listinfo/igraph-help > > > _______________________________________________ > igraph-help mailing list > igraph-help@nongnu.org > https://lists.nongnu.org/mailman/listinfo/igraph-help >
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