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"""Unary operations on graphs"""
# Copyright (C) 2004-2015 by
# Aric Hagberg <hagberg@lanl.gov>
# Dan Schult <dschult@colgate.edu>
# Pieter Swart <swart@lanl.gov>
# All rights reserved.
# BSD license.
import networkx as nx
__author__ = """\n""".join(['Aric Hagberg <aric.hagberg@gmail.com>',
'Pieter Swart (swart@lanl.gov)',
'Dan Schult(dschult@colgate.edu)'])
__all__ = ['complement', 'reverse']
def complement(G, name=None):
"""Return the graph complement of G.
Parameters
----------
G : graph
A NetworkX graph
name : string
Specify name for new graph
Returns
-------
GC : A new graph.
Notes
------
Note that complement() does not create self-loops and also
does not produce parallel edges for MultiGraphs.
Graph, node, and edge data are not propagated to the new graph.
"""
if name is None:
name = "complement(%s)" % (G.name)
R = G.__class__()
R.name = name
R.add_nodes_from(G)
R.add_edges_from(((n, n2)
for n, nbrs in G.adjacency()
for n2 in G if n2 not in nbrs
if n != n2))
return R
def reverse(G, copy=True):
"""Return the reverse directed graph of G.
Parameters
----------
G : directed graph
A NetworkX directed graph
copy : bool
If True, then a new graph is returned. If False, then the graph is
reversed in place.
Returns
-------
H : directed graph
The reversed G.
"""
if not G.is_directed():
raise nx.NetworkXError("Cannot reverse an undirected graph.")
else:
return G.reverse(copy=copy)
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