#!/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)
