Re: [igraph] Shortest Paths of Weighted networks in Pajek format

[Gábor Csárdi]

You need to turn on the attribute handler before reading the file, because the C attribute handler is turned off by default:

igraph_i_set_attribute_table(&igraph_cattribute_table);

See http://igraph.sourceforge.net/doc/html/ch12s02.html.

Gabor

On Thu, Dec 6, 2012 at 11:22 PM, Charles Novaes de Santana <address@hidden> wrote:

Dear all,

Just to keep this topic in a new thread I am writing you this new email.

Once I have calculated correctly the shortest paths of my large
networks, I would like to calculate it considering the weights of the
edges.

To do it I am using Igraph 0.6, Gcc compiler 4.6.3 in a Ubuntu 12.04
in a machine 32 bits.

I am trying to use the function igraph_shortest_paths_dijkstra. I know
I need to give the weights of the graph as parameter to this function,
and to read the weights I am using the macro EANV. But I got a
"Segmentation fault" in my program just when I run EANV.

I saw in the manual webpage
(http://igraph.sourceforge.net/doc/html/ch19s05.html) that "Only a
subset of the Pajek format is implemented", but there you also say
that "The `weight' edge attribute might be added if there are edge
weights present". My network file has the weights, but I am not sure
if the format is correct. Could it be my problem?

Could you be so kind in helping me (again), please?

Please find in attach a small network file I am testing, and below the
source code I am using (is the same I was using in the previous
thread, but with the proper changes in order to work with weights).


#include<igraph.h>

int main(void){

        igraph_t g1;
        igraph_matrix_t l1,v1;
        igraph_vs_t vertices;
        igraph_vector_t myweights;

        int i,j,nverts,nedges;
        FILE *ifile1;

        ifile1=fopen("./network.net", "r");
        if (ifile1==0) {return 10;}
        igraph_read_graph_pajek(&g1, ifile1);
        fclose(ifile1);

        nedges=igraph_ecount(&g1);
        igraph_vector_init(&myweights,nedges);
        EANV(&g1,"weight",&myweights);
        nverts = igraph_vcount(&g1);
        igraph_vs_all(&vertices);
        igraph_matrix_init(&l1,0,nverts );
        igraph_matrix_init(&v1,1,nverts );
        for(i=0;i<nverts;i++){
                igraph_shortest_paths_dijkstra(&g1,&v1,igraph_vss_1(i),vertices,&myweights,IGRAPH_ALL);
                igraph_matrix_rbind(&l1,&v1);
        }

        igraph_matrix_destroy(&l1);
        igraph_matrix_destroy(&v1);
        igraph_vs_destroy(&vertices);
        igraph_vector_destroy(&myweights);
        igraph_destroy(&g1);

        return;
}


Thank you very much for any help!

Best,

Charles
--
Um axé! :)

--
Charles Novaes de Santana
http://www.imedea.uib-csic.es/~charles
PhD student - Global Change
Laboratorio Internacional de Cambio Global
Department of Global Change Research
Instituto Mediterráneo de Estudios Avanzados(CSIC/UIB)
Calle Miquel Marques 21, 07190
Esporles - Islas Baleares - España

Office phone - +34 971 610 896
Cell phone - +34 660 207 940

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Gabor Csardi <address@hidden>     MTA KFKI RMKI