Roget¶
Build a directed graph of 1022 categories and 5075 cross-references as defined in the 1879 version of Roget’s Thesaurus contained in the datafile roget_dat.txt. This example is described in Section 1.2 in Knuth’s book (see [1] and [2]).
Note that one of the 5075 cross references is a self loop yet
it is included in the graph built here because
the standard networkx DiGraph
class allows self loops.
(cf. 400pungency:400 401 403 405).
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 |
Out:
Loaded roget_dat.txt containing 1022 categories.
digraph has 1022 nodes with 5075 edges
21 connected components
from __future__ import print_function
# Authors: Brendt Wohlberg, Aric Hagberg (hagberg@lanl.gov)
# Date: 2005-04-01 07:56:22 -0700 (Fri, 01 Apr 2005)
# Copyright (C) 2004-2018 by
# Aric Hagberg <hagberg@lanl.gov>
# Dan Schult <dschult@colgate.edu>
# Pieter Swart <swart@lanl.gov>
# All rights reserved.
# BSD license.
import gzip
import re
import sys
import matplotlib.pyplot as plt
from networkx import nx
def roget_graph():
""" Return the thesaurus graph from the roget.dat example in
the Stanford Graph Base.
"""
# open file roget_dat.txt.gz (or roget_dat.txt)
fh = gzip.open('roget_dat.txt.gz', 'r')
G = nx.DiGraph()
for line in fh.readlines():
line = line.decode()
if line.startswith("*"): # skip comments
continue
if line.startswith(" "): # this is a continuation line, append
line = oldline + line
if line.endswith("\\\n"): # continuation line, buffer, goto next
oldline = line.strip("\\\n")
continue
(headname, tails) = line.split(":")
# head
numfind = re.compile("^\d+") # re to find the number of this word
head = numfind.findall(headname)[0] # get the number
G.add_node(head)
for tail in tails.split():
if head == tail:
print("skipping self loop", head, tail, file=sys.stderr)
G.add_edge(head, tail)
return G
if __name__ == '__main__':
G = roget_graph()
print("Loaded roget_dat.txt containing 1022 categories.")
print("digraph has %d nodes with %d edges"
% (nx.number_of_nodes(G), nx.number_of_edges(G)))
UG = G.to_undirected()
print(nx.number_connected_components(UG), "connected components")
options = {
'node_color': 'black',
'node_size': 1,
'line_color': 'grey',
'linewidths': 0,
'width': 0.1,
}
nx.draw_circular(UG, **options)
plt.show()
Total running time of the script: ( 0 minutes 0.217 seconds)