networkx.to_scipy_sparse_matrix

to_scipy_sparse_matrix(G, nodelist=None, dtype=None)

Return the graph adjacency matrix as a SciPy sparse matrix.

Parameters:

G : graph

The NetworkX graph used to construct the NumPy matrix.

nodelist : list, optional

The rows and columns are ordered according to the nodes in nodelist. If nodelist is None, then the ordering is produced by G.nodes().

dtype : NumPy data-type, optional

A valid NumPy dtype used to initialize the array. If None, then the NumPy default is used.

Returns:

M : SciPy sparse matrix

Graph adjacency matrix.

Notes

The matrix entries are populated using the ‘weight’ edge attribute. When an edge does not have the ‘weight’ attribute, the value of the entry is 1. For multiple edges, the values of the entries are the sums of the edge attributes for each edge.

When nodelist does not contain every node in G, the matrix is built from the subgraph of G that is induced by the nodes in nodelist.

Uses lil_matrix format. To convert to other formats see the documentation for scipy.sparse.

Examples

>>> G = nx.MultiDiGraph()
>>> G.add_edge(0,1,weight=2)
>>> G.add_edge(1,0)
>>> G.add_edge(2,2,weight=3)
>>> G.add_edge(2,2)
>>> S = nx.to_scipy_sparse_matrix(G, nodelist=[0,1,2])
>>> S.todense()
matrix([[ 0.,  2.,  0.],
        [ 1.,  0.,  0.],
        [ 0.,  0.,  4.]])