#!/usr/bin/env python
"""
Routes to LANL from 186 sites on the Internet.
This uses Graphviz for layout so you need PyGraphviz or Pydot.
"""
__author__ = """Aric Hagberg (hagberg@lanl.gov)"""
# Copyright (C) 2004-2008
# Aric Hagberg <hagberg@lanl.gov>
# Dan Schult <dschult@colgate.edu>
# Pieter Swart <swart@lanl.gov>
# All rights reserved.
# BSD license.
def lanl_graph():
""" Return the lanl internet view graph from lanl.edges
"""
import networkx as nx
try:
fh=open('lanl_routes.edgelist','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
try:
from networkx import graphviz_layout
except ImportError:
raise ImportError("This example needs Graphviz and either PyGraphviz or Pydot")
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"
import matplotlib.pyplot as plt
plt.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=[G.rtt[v] for v in G],
with_labels=False,
alpha=0.5,
node_size=15)
# adjust the plot limits
xmax=1.02*max(xx for xx,yy in pos.values())
ymax=1.02*max(yy for xx,yy in pos.values())
plt.xlim(0,xmax)
plt.ylim(0,ymax)
plt.savefig("lanl_routes.png")
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