dgl.DGLGraph.incidence_matrix

DGLGraph.incidence_matrix(typestr, ctx=device(type='cpu'))[source]

Return the incidence matrix representation of this graph.

An incidence matrix is an n x m sparse matrix, where n is the number of nodes and m is the number of edges. Each nnz value indicating whether the edge is incident to the node or not.

There are three types of an incidence matrix \(I\):

  • in:

    • \(I[v, e] = 1\) if \(e\) is the in-edge of \(v\) (or \(v\) is the dst node of \(e\));
    • \(I[v, e] = 0\) otherwise.

  • out:

    • \(I[v, e] = 1\) if \(e\) is the out-edge of \(v\) (or \(v\) is the src node of \(e\));
    • \(I[v, e] = 0\) otherwise.

  • both:

    • \(I[v, e] = 1\) if \(e\) is the in-edge of \(v\);
    • \(I[v, e] = -1\) if \(e\) is the out-edge of \(v\);
    • \(I[v, e] = 0\) otherwise (including self-loop).
Parameters:
  • typestr (str) – Can be either in, out or both
  • ctx (context, optional (default=cpu)) – The context of returned incidence matrix.
Returns:

The incidence matrix.
Return type:

SparseTensor