This documents an unmaintained version of NetworkX. Please upgrade to a maintained version and see the current NetworkX documentation.

Source code for networkx.algorithms.components.semiconnected

# -*- coding: utf-8 -*-
#    Copyright (C) 2004-2019 by
#    Aric Hagberg <hagberg@lanl.gov>
#    Dan Schult <dschult@colgate.edu>
#    Pieter Swart <swart@lanl.gov>
#    All rights reserved.
#    BSD license.
# Authors: ysitu (ysitu@users.noreply.github.com)
import networkx as nx
from networkx.utils import not_implemented_for, pairwise

__all__ = ['is_semiconnected']

[docs]@not_implemented_for('undirected') def is_semiconnected(G): """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. 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) path = nx.topological_sort(G) return all(G.has_edge(u, v) for u, v in pairwise(path))