65 lines
1.6 KiB
Python
65 lines
1.6 KiB
Python
"""Unary operations on graphs"""
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# Copyright (C) 2004-2019 by
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# Aric Hagberg <hagberg@lanl.gov>
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# Dan Schult <dschult@colgate.edu>
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# Pieter Swart <swart@lanl.gov>
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# All rights reserved.
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# BSD license.
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import networkx as nx
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from networkx.utils import not_implemented_for
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__author__ = """\n""".join(['Aric Hagberg <aric.hagberg@gmail.com>',
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'Pieter Swart (swart@lanl.gov)',
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'Dan Schult(dschult@colgate.edu)'])
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__all__ = ['complement', 'reverse']
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def complement(G):
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"""Returns the graph complement of G.
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Parameters
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----------
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G : graph
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A NetworkX graph
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Returns
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-------
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GC : A new graph.
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Notes
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------
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Note that complement() does not create self-loops and also
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does not produce parallel edges for MultiGraphs.
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Graph, node, and edge data are not propagated to the new graph.
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"""
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R = G.__class__()
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R.add_nodes_from(G)
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R.add_edges_from(((n, n2)
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for n, nbrs in G.adjacency()
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for n2 in G if n2 not in nbrs
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if n != n2))
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return R
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def reverse(G, copy=True):
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"""Returns the reverse directed graph of G.
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Parameters
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----------
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G : directed graph
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A NetworkX directed graph
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copy : bool
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If True, then a new graph is returned. If False, then the graph is
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reversed in place.
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Returns
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-------
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H : directed graph
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The reversed G.
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"""
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if not G.is_directed():
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raise nx.NetworkXError("Cannot reverse an undirected graph.")
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else:
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return G.reverse(copy=copy)
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