Re: [igraph] Question on max id node

[Gabor Csardi]

Richard, this is quite strange indeed. I've just tried read_graph_ncol
with various graphs and it seems to work fine. Could you send 
me a small file that reproduces the strange results?

Btw, is this the 0.5 version?

Thanks,
G.

On Sun, Mar 09, 2008 at 06:22:42PM -0400, Richard Geddes wrote:
> Well, initially I imported an edgelist with
> 
> igraph_read_graph_edgelist(&graph, input_file, 0, false);
> 
> and ran
> 
> igraph_community_fastgreedy(&graph, NULL, &merges, &modularity);
> 
> and got normal results.
> 
> Then, to get at the graph attributes,  I attached the C attribute handler:
> 
> igraph_i_set_attribute_table(&igraph_cattribute_table);
> 
> imported the edgelist with:
> 
> igraph_read_graph_ncol(&graph, input_file, NULL true, false,
> IGRAPH_UNDIRECTED);
> 
> and ran the community function on the graph and I get different results...
> 
> when importing with igraph_read_graph_edgelist, 11 nodes and 19 edges are
> reported are reported.. which is correct,
> however when importing with the igraph_read_graph_ncol function, 19 nodes and
> 19 edges are reported.
> 
> Am I using igraph_read_graph_ncol correctly?
> 
> Thanks
> Richard
> 
> Richard Geddes wrote:
> 
>     Thanks.  Looks like what I was looking for.
> 
>     Tamas Nepusz wrote:
> 
> 
>         Hi Richard,
> 
> 
> 
>             Is there a function that provides the value of the largest node 
> id in
>             the imported graph?
> 
> 
> 
>         If you are using C (I assume you do), try to attach the C attribute
>         handler and then read your graph using igraph_read_graph_ncol (this is
>         for the NCOL format which is practically a named edge list). This is
>         able to store the vertex names used in the NCOL file as a vertex
>         attribute. After that, you can scan the attribute values to find the
>         largest one.
> 
>         See http://cneurocvs.rmki.kfki.hu/igraph/doc-0.5/html/ch09s02.html for
>         the usage of the C attribute handler.
> 
> 
> 
> 
> 
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> 
> 

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-- 
Csardi Gabor <address@hidden>    UNIL DGM