"""
SGBWords() returns an undirected graph over the 5757 5-letter
words in the datafile words_dat.txt. Two words are connected by an edge
if they differ in one letter, resulting in 14,135 edges. This example
is described in Section 1.1 in Knuth's book [1,2].
References.
----------
[1] Donald E. Knuth,
"The Stanford GraphBase: A Platform for Combinatorial Computing",
ACM Press, New York, 1993.
[2] http://www-cs-faculty.stanford.edu/~knuth/sgb.html
"""
__author__ = """Brendt Wohlberg\nAric Hagberg (hagberg@lanl.gov)"""
__date__ = "$Date: 2005-04-01 07:56:04 -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>
# All rights reserved.
# BSD license.
from networkx import *
import re
import sys
__author__ = """"""
__date__ = ""
__credits__ = """"""
__version__ = ""
# $Header$
#-------------------------------------------------------------------
# The Words/Ladder graph of Section 1.1
#-------------------------------------------------------------------
def _notComment(line):
return not(line.startswith('*'))
def _wdist(a,b):
""" Return simple edit distance between two words a and b. """
d=abs(len(a)-len(b))
for k in range(0,min(len(a),len(b))):
if a[k] != b[k]:
d = d + 1
return d
def words_graph():
""" Return the words example graph from the Stanford GraphBase"""
import sys
# open file words_dat.txt.gz (or words_dat.txt)
try:
try:
import gzip
fh=gzip.open('words_dat.txt.gz','r')
except:
fh=open("words_dat.txt","r")
except IOError:
raise "File words_dat.txt not found."
G = Graph(name="words")
sys.stderr.write("Loading words_dat.txt: ")
for line in fh.readlines():
if line.startswith("*"):
continue
w=line[0:5]
G.add_node(w)
nwords=number_of_nodes(G)
words=G.nodes()
for k in xrange(0,nwords):
if (k%100==0):
sys.stderr.softspace=0
sys.stderr.write(".")
for l in xrange(k+1,nwords):
if _wdist(words[k],words[l]) == 1:
G.add_edge(words[k],words[l])
return G
if __name__ == '__main__':
from networkx import *
G=words_graph()
print "Loaded words_dat.txt containing 5757 five-letter English words."
print "Two words are connected if they differ in one letter."
print "graph has %d nodes with %d edges"\
%(number_of_nodes(G),number_of_edges(G))
sp=shortest_path(G, 'chaos', 'order')
print "shortest path between 'chaos' and 'order' is:\n", sp
sp=shortest_path(G, 'nodes', 'graph')
print "shortest path between 'nodes' and 'graph' is:\n", sp
sp=shortest_path(G, 'pound', 'marks')
print "shortest path between 'pound' and 'marks' is:\n", sp
print number_connected_components(G),"connected components"
|