I'm trying to identify communities in a direct graph.
I only know how to use Spectral clustering and Girvan-Newman method but the both the methods work only with undirect graph. Am I wrong?
So what method could I use to solve the following problem?
The text of the problem is the following:
Trawling - Identify the communities of the following webgraph with a minimum support of two and a minimum itemset size of two. Plot the resulting bipartite graphs.
What I tried to do was using Spectral Clustering: I transcribed the graph but what I obtained was a squared non-symmetric Adjacency matrix (A).
When there is an arrow from 1 to 2 the value a12 in the matrix is 1 instead the value a21 is 0.
Now I've problems calculating the Degree Matrix (D). All its values are 0 except for the ones along the main diagonal that are the sum of the values in their rows. Is it correct?
Finally I calculate the Laplacian Matrix (L) computing: L=D-A
Now I'm stuck I don't know how to go on, how do I calculate Eigenvalues and Eigenvectors?