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exercises-in-programming-style/24-declared-intentions/tf-24.py
2013-11-28 20:54:31 -08:00

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Python
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#!/usr/bin/env python
import sys, re, operator, string, inspect
#
# Decorator for enforcing types of arguments in method calls
#
class AcceptTypes():
def __init__(self, *args):
self._args = args
def __call__(self, f):
def wrapped_f(*args):
for i in range(len(self._args)):
if type(args[i]) <> self._args[i]:
raise TypeError("Expecting %s got %s" % (str(self._args[i]), str(type(args[i]))))
return f(*args)
return wrapped_f
#
# The functions
#
@AcceptTypes(str)
def extract_words(path_to_file):
"""
Takes a path to a file and returns the non-stop
words, after properly removing nonalphanumeric chars
and normalizing for lower case
"""
with open(path_to_file) as f:
str_data = f.read()
pattern = re.compile('[\W_]+')
word_list = pattern.sub(' ', str_data).lower().split()
with open('../stop_words.txt') as f:
stop_words = f.read().split(',')
stop_words.extend(list(string.ascii_lowercase))
return [w for w in word_list if not w in stop_words]
@AcceptTypes(list)
def frequencies(word_list):
"""
Takes a list of words and returns a dictionary associating
words with frequencies of occurrence
"""
word_freqs = {}
for w in word_list:
if w in word_freqs:
word_freqs[w] += 1
else:
word_freqs[w] = 1
return word_freqs
@AcceptTypes(dict)
def sort(word_freq):
"""
Takes a dictionary of words and their frequencies
and returns a list of pairs where the entries are
sorted by frequency
"""
return sorted(word_freq.iteritems(), key=operator.itemgetter(1), reverse=True)
#
# The main function
#
word_freqs = sort(frequencies(extract_words(sys.argv[1])))
for tf in word_freqs[0:25]:
print tf[0], ' - ', tf[1]