networkx.algorithms.components.strongly_connected_components

strongly_connected_components(G)[source]

Generate nodes in strongly connected components of graph.

Parameters

G (NetworkX Graph) – A directed graph.

Returns

comp – A generator of sets of nodes, one for each strongly connected component of G.

Return type

generator of sets

Raises

NetworkXNotImplemented – If G is undirected.

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)

Notes

Uses Tarjan’s algorithm[1]_ with Nuutila’s modifications[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)..