Thank you so much for those quick answers !

Le ven. 14 juin 2019 à 11:57, Felix Victor Münch <[email protected]>
a écrit :

> Hi Jean,
>
>
> I did a hierarchical SBM on a Twitter follow network (pretty sparse
> actually in comparison to other kinds of networks) with ca. 250k accounts.
> It took about "11 days for one run, with 60 vCPUs and a peak usage of ca.
> 400 GB RAM" (my PhD thesis, https://eprints.qut.edu.au/125543/, p. 251).
> How useful it is theoretically depends on your goals and discipline. In my
> case, feel free to read the referenced chapter and decide for yourself.
>
> I also did runs on smaller networks with ca 100k -150k nodes. Running time
> was still about in the same ball park, or even longer … I guess because the
> network structure was more complex.
>
> The amount of RAM is pretty mandatory. Swap memory won't help you much, as
> it slows the algorithm down to a degree that makes the running time
> infeasible. Number of CPUs could be lower I guess, because much of the algo
> seemed to run serially and those parts made up most of the calculation time.
>
> I had a university/QRIScloud (https://www.qriscloud.org.au/) provided VM
> with 60 cores and 900 GB RAM. On a Google VM this would have been pretty
> costly. I adjusted epsilon for less accuracy and greater speed:
>
> state = gt.inference.minimize_nested_blockmodel_dl(core, verbose=True, 
> mcmc_equilibrate_args={'epsilon': 1e-2}, )
>
> (
> https://github.com/FlxVctr/PhD-code/blob/master/1000%2B%20nested%20SBM.ipynb
> )
>
> If I wouldn't have had the computing ressources for free I wouldn't have
> done it.
>
> I'd recommend to test infomap if you're looking for a more efficient
> alternative (https://www.mapequation.org/index.html) that also works with
> entropy minimization (even though it's more flow oriented). Just did a 181k
> network community detection (non-hierarchical) in a matter of seconds on a
> last-year's Macbook Pro yesterday. I don't know how long it takes for a
> hierarchical structure, but it can do this, so it's worth a try.
>
> Also efficient, but with all the drawbacks that Tiago Peixoto elaborates
> on in his papers (which I also refer to in the chapter linked above), and
> not hierarchical, is the parallelised modularity maximisation (Parallelised
> Louvain Method) PLM in NetworKit (https://networkit.github.io/). Despite
> it's theoretical and statistical drawbacks it delivers good heuristical
> evidence for communities in networks imho. But that depends a lot on what
> you want to do
>
>
> Cheers,
>
>
> Felix
>
>
>
> *Dr. Felix Victor Münch*
> Postdoc Researcher
> Leibniz Institut for Media Research | Hans-Bredow-Institut (HBI), Hamburg
> https://leibniz-hbi.de/
> https://felixvictor.net
>
>
> On Friday, Jun 14, 2019 at 10:16 AM, Lietz Haiko <[email protected]>
> wrote:
> Hi Jean,
>
> the answer also depends how complicated the desired SBM is. A layered
> model takes longer than an unlayered one.
>
> Modeling a graph with 100k nodes should take very long. But I'd also be
> interested in a more informed answer...
>
> Haiko
>
>
>
> ------------------------------
> *Von:* graph-tool [[email protected]]" im Auftrag von "Jean
> Christophe Cazes [[email protected]]
> *Gesendet:* Freitag, 14. Juni 2019 09:59
> *An:* [email protected]
> *Betreff:* [graph-tool] [SBM on Dense Graphs]
>
> Hello, I intend to use graph_tool for a big network, +100k nodes and very
> dense.
>
> The dataset i'm working with at the moment is ~ 40/50 GB csv containing
> vertices and edges as transactions.
>
> Is it realistic to try SBM on such graph both computationnally and would
> this be theoretically useful?
>
> If it isnt computationnally, how big can my subgraph be in order to be
> feasible?
>
> Note: I will rent a Google Cloud Platform VM to do so.
>
> Thank you
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