81 lines
2.2 KiB
Python
81 lines
2.2 KiB
Python
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"""
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=====
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Roget
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=====
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Build a directed graph of 1022 categories and 5075 cross-references as defined
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in the 1879 version of Roget's Thesaurus. This example is described in Section
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1.2 of
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Donald E. Knuth, "The Stanford GraphBase: A Platform for Combinatorial
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Computing", ACM Press, New York, 1993.
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http://www-cs-faculty.stanford.edu/~knuth/sgb.html
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Note that one of the 5075 cross references is a self loop yet it is included in
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the graph built here because the standard networkx `DiGraph` class allows self
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loops. (cf. 400pungency:400 401 403 405).
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The data file can be found at:
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- https://github.com/networkx/networkx/blob/master/examples/graph/roget_dat.txt.gz
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"""
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import gzip
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import re
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import sys
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import matplotlib.pyplot as plt
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from networkx import nx
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def roget_graph():
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""" Return the thesaurus graph from the roget.dat example in
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the Stanford Graph Base.
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"""
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# open file roget_dat.txt.gz
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fh = gzip.open("roget_dat.txt.gz", "r")
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G = nx.DiGraph()
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for line in fh.readlines():
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line = line.decode()
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if line.startswith("*"): # skip comments
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continue
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if line.startswith(" "): # this is a continuation line, append
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line = oldline + line
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if line.endswith("\\\n"): # continuation line, buffer, goto next
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oldline = line.strip("\\\n")
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continue
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(headname, tails) = line.split(":")
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# head
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numfind = re.compile(r"^\d+") # re to find the number of this word
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head = numfind.findall(headname)[0] # get the number
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G.add_node(head)
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for tail in tails.split():
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if head == tail:
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print("skipping self loop", head, tail, file=sys.stderr)
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G.add_edge(head, tail)
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return G
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G = roget_graph()
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print("Loaded roget_dat.txt containing 1022 categories.")
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print(f"digraph has {nx.number_of_nodes(G)} nodes with {nx.number_of_edges(G)} edges")
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UG = G.to_undirected()
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print(nx.number_connected_components(UG), "connected components")
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options = {
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"node_color": "black",
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"node_size": 1,
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"edge_color": "gray",
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"linewidths": 0,
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"width": 0.1,
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}
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nx.draw_circular(UG, **options)
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plt.show()
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