#!/usr/bin/env python """ Atlas of all graphs of 6 nodes or less. """ __author__ = """Aric Hagberg (hagberg@lanl.gov)""" # Copyright (C) 2008 by # Aric Hagberg <hagberg@lanl.gov> # Dan Schult <dschult@colgate.edu> # Pieter Swart <swart@lanl.gov> # Distributed under the terms of the GNU Lesser General Public License # http://www.gnu.org/copyleft/lesser.html from networkx import * from networkx.generators.atlas import * from networkx import graph_could_be_isomorphic as isomorphic import random def atlas6(): """ Return the atlas of all connected graphs of 6 nodes or less. Attempt to check for isomorphisms and remove. """ Atlas=graph_atlas_g()[0:158] # 208 # remove isolated nodes, only connected graphs are left U=Graph() # graph for union of all graphs in atlas for G in Atlas: zerodegree=[n for n in G if G.degree(n)==0] for n in zerodegree: G.delete_node(n) U=disjoint_union(U,G) # list of graphs of all connected components C=connected_component_subgraphs(U) UU=Graph() # do quick isomorphic-like check, not a true isomorphism checker nlist=[] # list of nonisomorphic graphs for G in C: # check against all nonisomorphic graphs so far if not iso(G,nlist): nlist.append(G) UU=disjoint_union(UU,G) # union the nonisomorphic graphs return UU def iso(G1, glist): """Quick and dirty nonisomorphism checker used to check isomorphisms.""" for G2 in glist: if isomorphic(G1,G2): return True return False if __name__ == '__main__': import networkx as nx import random G=atlas6() print "graph has %d nodes with %d edges"\ %(number_of_nodes(G),number_of_edges(G)) print number_connected_components(G),"connected components" C=nx.connected_component_subgraphs(G) UG=nx.UbiGraph(G) for g in C: x = random.randint(0,256*256*256) UG.set_node_attr(g.nodes(),color='#%06x'%x)