networkx.generators.degree_seq.directed_configuration_model¶

directed_configuration_model
(in_degree_sequence, out_degree_sequence, create_using=None, seed=None)[source]¶ Returns a directed_random graph with the given degree sequences.
The configuration model generates a random directed pseudograph (graph with parallel edges and self loops) by randomly assigning edges to match the given degree sequences.
 Parameters
in_degree_sequence (list of nonnegative integers) – Each list entry corresponds to the indegree of a node.
out_degree_sequence (list of nonnegative integers) – Each list entry corresponds to the outdegree of a node.
create_using (NetworkX graph constructor, optional (default MultiDiGraph)) – Graph type to create. If graph instance, then cleared before populated.
seed (integer, random_state, or None (default)) – Indicator of random number generation state. See Randomness.
 Returns
G – A graph with the specified degree sequences. Nodes are labeled starting at 0 with an index corresponding to the position in deg_sequence.
 Return type
 Raises
NetworkXError – If the degree sequences do not have the same sum.
See also
Notes
Algorithm as described by Newman 1.
A nongraphical degree sequence (not realizable by some simple graph) is allowed since this function returns graphs with self loops and parallel edges. An exception is raised if the degree sequences does not have the same sum.
This configuration model construction process can lead to duplicate edges and loops. You can remove the selfloops and parallel edges (see below) which will likely result in a graph that doesn’t have the exact degree sequence specified. This “finitesize effect” decreases as the size of the graph increases.
References
 1
Newman, M. E. J. and Strogatz, S. H. and Watts, D. J. Random graphs with arbitrary degree distributions and their applications Phys. Rev. E, 64, 026118 (2001)
Examples
One can modify the in and outdegree sequences from an existing directed graph in order to create a new directed graph. For example, here we modify the directed path graph:
>>> D = nx.DiGraph([(0, 1), (1, 2), (2, 3)]) >>> din = list(d for n, d in D.in_degree()) >>> dout = list(d for n, d in D.out_degree()) >>> din.append(1) >>> dout[0] = 2 >>> # We now expect an edge from node 0 to a new node, node 3. ... D = nx.directed_configuration_model(din, dout)
The returned graph is a directed multigraph, which may have parallel edges. To remove any parallel edges from the returned graph:
>>> D = nx.DiGraph(D)
Similarly, to remove selfloops:
>>> D.remove_edges_from(nx.selfloop_edges(D))