strongly_connected_components¶

strongly_connected_components(G)[source]¶

Generate nodes in strongly connected components of graph.

Parameters

GNetworkX Graph: A directed graph.

Returns

compgenerator of sets: A generator of sets of nodes, one for each strongly connected component of G.

Raises

NetworkXNotImplemented: If G is undirected.

See also

connected_components
weakly_connected_components
kosaraju_strongly_connected_components

Notes

Uses Tarjan’s algorithm[R827335e01166-1]_ with Nuutila’s modifications[R827335e01166-2]_. Nonrecursive version of algorithm.

References

1: Depth-first search and linear graph algorithms, R. Tarjan SIAM Journal of Computing 1(2):146-160, (1972).
2: On finding the strongly connected components in a directed graph. E. Nuutila and E. Soisalon-Soinen Information Processing Letters 49(1): 9-14, (1994)..

Examples

Generate a sorted list of strongly connected components, largest first.

>>> G = nx.cycle_graph(4, create_using=nx.DiGraph())
>>> nx.add_cycle(G, [10, 11, 12])
>>> [
...     len(c)
...     for c in sorted(nx.strongly_connected_components(G), key=len, reverse=True)
... ]
[4, 3]

If you only want the largest component, it’s more efficient to use max instead of sort.

>>> largest = max(nx.strongly_connected_components(G), key=len)