Lanl Routes

[source code]

#!/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>
#    Distributed under the terms of the GNU Lesser General Public License
#    http://www.gnu.org/copyleft/lesser.html


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(xx for xx,yy in pos.values())
    plt.xlim(0,xmax)
    plt.ylim(0,ymax)
    plt.savefig("lanl_routes.png")