Re: [igraph] Nodes properties

[Gábor Csárdi]

From the docs at http://igraph.org/c/doc/igraph-Attributes.html#idm344008595600:

Please note that the attribute handler must be attached before you call any other igraph functions, otherwise you might end up with graphs without attributes and an active attribute handler, which might cause unexpected program behaviour. The rule is that you attach the attribute handler in the beginning of your main() and never touch it again. (Detaching the attribute handler might lead to memory leaks.)

Also, consider passing pointers to igraph_t to functions, otherwise you might get into trouble. The fixed code is below. G.

#include <igraph.h>

void f(igraph_t *g, double number){

     igraph_real_t N = number;  

     SETGAN(g, "number", N);

}

int main(void){

    igraph_t g;

    float N = 50.0;

    igraph_integer_t Kin = 8.0;

    igraph_bool_t directed = 1;

    igraph_i_set_attribute_table(&igraph_cattribute_table);

    igraph_erdos_renyi_game(&g, IGRAPH_ERDOS_RENYI_GNM, N, N*Kin/2.0, directed, 0);

        

    f(&g, 0.2);

return 0;

}

On Tue, Jan 13, 2015 at 12:09 PM, Daniel Penalva <address@hidden> wrote:

that's it:

http://pastebin.com/fAjX2M78

On Tue, Jan 13, 2015 at 2:56 PM, Gábor Csárdi <address@hidden> wrote:

Please send complete code that reproduces the error. Thanks. G.

On Tue, Jan 13, 2015 at 11:55 AM, Daniel Penalva <address@hidden> wrote:

i setted igraph_i_set_attribute_table(&igraph_cattribute_table) in the  int main(void)

On Tue, Jan 13, 2015 at 2:46 PM, Daniel Penalva <address@hidden> wrote:

Hi

Iam trying to use this interface, but got a error when encapsulated the functions inside another, eg:

void  f(igraph_t g, double prickles){

igraph_real_t good = prickles;

SETGAN(&g, "food", good);

}

got a error:

vector_ptr.c:258: igraph_vector_ptr_size: Assertion `v != ((void *)0)' failed.

any hint ? thank-you

On Mon, Jan 12, 2015 at 2:25 PM, Daniel Penalva <address@hidden> wrote:

thank you

On Mon, Jan 12, 2015 at 7:56 AM, Tamas Nepusz <address@hidden> wrote:

Hi,

> How can i add properties to the nodes of a graph ? Iam using igraph with C
> language.
Please refer to http://igraph.org/c/doc/igraph-Attributes.html

> I want to add:
>
> char *
> doubles
> int
>
> and access by the adjacency matrix structure.  Is there any doc to this ?
igraph does not use adjacency matrices to represent a graph. If you want to
retrieve an attribute corresponding to an edge, you have to query the ID of the
edge first using igraph_get_eid() and then retrieve the attribute of interest
using igraph_cattribute_EAN() for numeric attributes, igraph_cattribute_EAS()
for string attributes, or igraph_cattribute_EAB() for booleans.

--
T.

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