networkx.utils.rcm.reverse_cuthill_mckee_ordering¶

reverse_cuthill_mckee_ordering(G, heuristic=None)[source]¶

Generate an ordering (permutation) of the graph nodes to make a sparse matrix.

Uses the reverse Cuthill-McKee heuristic (based on breadth-first search) 1.

Parameters

G (graph) – A NetworkX graph
heuristic (function, optional) – Function to choose starting node for RCM algorithm. If None a node from a pseudo-peripheral pair is used. A user-defined function can be supplied that takes a graph object and returns a single node.

Returns

nodes – Generator of nodes in reverse Cuthill-McKee ordering.

Return type

generator

Examples

>>> from networkx.utils import reverse_cuthill_mckee_ordering
>>> G = nx.path_graph(4)
>>> rcm = list(reverse_cuthill_mckee_ordering(G))
>>> A = nx.adjacency_matrix(G, nodelist=rcm) 

Smallest degree node as heuristic function:

>>> def smallest_degree(G):
...     return min(G, key=G.degree)
>>> rcm = list(reverse_cuthill_mckee_ordering(G, heuristic=smallest_degree))