My second Python script, dispersion.py

Posted on November 19, 2014 in Uncategorized by Eric Lease Morgan

This is my second Python script, dispersion.py, and it illustrates where common words appear in a text. 

#!/usr/bin/env python2

# dispersion.py - illustrate where common words appear in a text
#
# usage: ./dispersion.py <file>

# Eric Lease Morgan <emorgan@nd.edu>
# November 19, 2014 - my second real python script; "Thanks for the idioms, Don!"


# configure
MAXIMUM = 25
POS     = 'NN'

# require
import nltk
import operator
import sys

# sanity check
if len( sys.argv ) != 2 :
  print "Usage:", sys.argv[ 0 ], "<file>"
  quit()
  
# get input
file = sys.argv[ 1 ]

# initialize
with open( file, 'r' ) as handle : text = handle.read()
sentences = nltk.sent_tokenize( text )
pos       = {}

# process each sentence
for sentence in sentences : 
  
  # POS the sentence and then process each of the resulting words
  for word in nltk.pos_tag( nltk.word_tokenize( sentence ) ) :
    
    # check for configured POS, and increment the dictionary accordingly
    if word[ 1 ] == POS : pos[ word[ 0 ] ] = pos.get( word[ 0 ], 0 ) + 1

# sort the dictionary
pos = sorted( pos.items(), key = operator.itemgetter( 1 ), reverse = True )

# do the work; create a dispersion chart of the MAXIMUM most frequent pos words
text = nltk.Text( nltk.word_tokenize( text ) )
text.dispersion_plot( [ p[ 0 ] for p in pos[ : MAXIMUM ] ] )

# done
quit()

I used the program to analyze two works: 1) Thoreau’s Walden, and 2) Emerson’s Representative Men. From the dispersion plots displayed below, we can conclude a few things:

  • The words “man”, “life”, “day”, and “world” are common between both works.
  • Thoreau discusses water, ponds, shores, and surfaces together.
  • While Emerson seemingly discussed man and nature in the same breath, but none of his core concepts are discussed as densely as Thoreau’s.
Thoreau's Walden

Thoreau’s Walden

Emerson's Representative Men

Emerson’s Representative Men

Python’s Natural Langauge Toolkit (NLTK) is a good library to get start with for digital humanists. I have to learn more though. My jury is still out regarding which is better, Perl or Python. So far, they have more things in common than differences.

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