Source code for networkx.algorithms.components.semiconnected

import networkx as nx
from networkx.utils import not_implemented_for, pairwise

__all__ = ["is_semiconnected"]

[docs]@not_implemented_for("undirected") def is_semiconnected(G, topo_order=None): """Returns True if the graph is semiconnected, False otherwise. A graph is semiconnected if, and only if, for any pair of nodes, either one is reachable from the other, or they are mutually reachable. Parameters ---------- G : NetworkX graph A directed graph. topo_order: list or tuple, optional A topological order for G (if None, the function will compute one) Returns ------- semiconnected : bool True if the graph is semiconnected, False otherwise. Raises ------ NetworkXNotImplemented If the input graph is undirected. NetworkXPointlessConcept If the graph is empty. Examples -------- >>> G = nx.path_graph(4, create_using=nx.DiGraph()) >>> print(nx.is_semiconnected(G)) True >>> G = nx.DiGraph([(1, 2), (3, 2)]) >>> print(nx.is_semiconnected(G)) False See Also -------- is_strongly_connected is_weakly_connected is_connected is_biconnected """ if len(G) == 0: raise nx.NetworkXPointlessConcept( "Connectivity is undefined for the null graph." ) if not nx.is_weakly_connected(G): return False G = nx.condensation(G) if topo_order is None: topo_order = nx.topological_sort(G) return all(G.has_edge(u, v) for u, v in pairwise(topo_order))