Hello,
I want to build non-directed and weighted graphs with average degree ranging
1-5 (variation variable g). The weights are assigned to edges are stored in W
(symmetric matrix of size 300 x 300, which is not changed) matrix. The stretch
of the highlighted code creates multiple edges, for this reason, I am using the
igraph_simplify () function. But probably the logic of the code is incorrect,
because the weight of the same edge is changing when the average degree
undergoes variation. For example, if I have 20 vertex connected to vertex 40
weighing 0123 on a graph with average degree equal to 1, when the average
degree is incremented the same edge appears with a distinct weight, for
example, 0555. The weights should remain constant throughout the execution of
the code, because the matrix W keeps unchanged. Segue abaixo, o trecho de
código.:
void TNetData::MatrixSimilarity(float sigma, int degree_initial, int
degree_final)
{
VectorXf v1, v2;
MatrixXf W(NOS,NOS);
int g, i, j, from, to;
float value, degree_average, similarity;
igraph_integer_t eid;
igraph_vector_t weights, degree;
igraph_attribute_combination_t edge_comb;
igraph_attribute_combination(&edge_comb, "weight" ,
IGRAPH_ATTRIBUTE_COMBINE_FIRST, IGRAPH_NO_MORE_ATTRIBUTES);
igraph_vector_init(&weights, 0);
igraph_vector_init(°ree,NOS);
igraph_vector_null(°ree);
W = ArrayXXf::Zero(NOS,NOS);
SETGAN(&net,"weighted", 1);
nSigma = sigma;
sigma = sigma*sigma*2.0;
// Construction of symmetric weight matrix
for (i = 0 ; i < NOS ; i++){
v1 = data.row(i);
for (j = 0 ; j < NOS ; j++){
if(i == j)
{
W(i,j) = 0.0;
W(j,i) = 0.0;
}
else{
v2 = data.row(j);
value = dist.GetDistance(v1,v2);
value = value / sigma;
value = exp(-value);
W(i,j) = value; // value is obtained using the Euclidean
distance between vectors of examples
W(j,i) = value;
}
}
}
for(g = initial_degree; g <= final_degree; g++) // g variation of the
average degree
{
igraph_degree(&net, °ree, igraph_vss_all(), IGRAPH_ALL,
IGRAPH_NO_LOOPS);
degree_average = (igraph_vector_sum(°ree)/(float)NOS);
eid = 0;
while(degree_average <= (float)g)
{
do
{
from = (rand()%(NOS-1)); // vertices are drawn and connected
// NOS - number of Samples
to = (rand()%(NOS-1));
}while(from == to);
igraph_add_edge(&net,from,to); // edge is connected to the graph
similarity = W(from,to) = W(to,from); // similarity variable
receives the value of the weight stored in W
//igraph_vector_push_back(&weights,similarity);
SETEAN(&net, "weight", eid, similarity); // the edge is set
to the value of the weight matrix W sought in
eid++; // stores the number of edges connected to the graph
igraph_degree(&net, °ree, igraph_vss_all(), IGRAPH_ALL,
IGRAPH_NO_LOOPS);
degree_average = (igraph_vector_sum(°ree)/(float)NOS); //
average degree is calculated
}
//for (i = 0; i < eid; i++)
//{
//SETEAN(&net, "weight", i, VECTOR(weights)[i]);
//}
igraph_simplify(&net,1,1,&edge_comb);
SaveNetwork(g); // method responsible for saving the graph generated
for each average degree
}
igraph_vector_destroy(&weights);
igraph_vector_destroy(°ree);
igraph_attribute_combination_destroy(&edge_comb);
}
Thank you!
> Date: Tue, 18 Nov 2014 10:44:58 +0100
> From: [email protected]
> To: [email protected]
> Subject: Re: [igraph] : multiple edges
>
> Hello,
>
> We cannot tell you what's wrong with your code without showing us a *small*
> example that demonstrates the problem.
>
> T.
>
> On 11/18, patricia wrote:
> > I am creating a weighted and undirected graph as follows:
> > - Draw two vertices randomly and make the connection between them, with a
> > weight value that is stored in an array in assorted positions. The values
> > that are stored in this matrix are unchanged.
> > For example, the sorteei positions 10 and 15 will in the weight matrix on
> > the line 10 and column 15, the value stored in that position will be the
> > weight of edge 10 --- 15.
> > But my code is generating multiple edges, so I'm using the igraph_simplify
> > (& net, 1,1, & edge_comb) with igraph_attribute_combination attribute (&
> > edge_comb, "weight", IGRAPH_ATTRIBUTE_COMBINE_FIRST,
> > IGRAPH_NO_MORE_ATTRIBUTES) function to eliminate them. But I want the value
> > of the weights remain unchanged; but even using the above attribute
> > (COMBINE_FIRST) weights are changing. What can I do to correct this error?
> >
> > Thank you
>
> > _______________________________________________
> > igraph-help mailing list
> > [email protected]
> > https://lists.nongnu.org/mailman/listinfo/igraph-help
>
>
> --
> T.
>
> _______________________________________________
> igraph-help mailing list
> [email protected]
> https://lists.nongnu.org/mailman/listinfo/igraph-help
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