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#!/usr/bin/env python
"""
Routes to LANL from 186 sites on the Internet.
"""
__author__ = """Aric Hagberg (hagberg@lanl.gov)"""
__date__ = "$Date: 2005-04-01 11:51:23 -0700 (Fri, 01 Apr 2005) $"
__credits__ = """"""
__revision__ = ""
# Copyright (C) 2004 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
import sys
def lanl_graph():
""" Return the lanl internet view graph from lanl.edges
"""
try:
fh=open("lanl.edges","r")
except IOError:
print "lanl.edges not found"
raise
G=NX.Graph()
time={}
time[0]=0 # assign 0 to center node
for line in fh.readlines():
(head,tail,rtt)=line.split()
G.add_edge(int(head),int(tail))
time[int(head)]=float(rtt)
# get largest component and assign ping times to G0time dictionary
G0=NX.connected_component_subgraphs(G)[0]
G0.rtt={}
for n in G0:
G0.rtt[n]=time[n]
return G0
if __name__ == '__main__':
import networkx as NX
import math
G=lanl_graph()
print "graph has %d nodes with %d edges"\
%(NX.number_of_nodes(G),NX.number_of_edges(G))
print NX.number_connected_components(G),"connected components"
try: # drawing
import pylab as P
P.figure(figsize=(8,8))
# use graphviz to find radial layout
pos=NX.graphviz_layout(G,prog="twopi",root=0)
# draw nodes, coloring by rtt ping time
NX.draw(G,pos,
node_color=P.array([G.rtt[v] for v in G]),
with_labels=False,
alpha=0.5,
node_size=15)
P.savefig("lanl.png")
print "Wrote lanl.png"
except:
print "This example could not find pylab or graphviz for drawing."
pass
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