Report the most common phrases in a text file

textanalyzer.py

#!/usr/bin/env python3

from collections import Counter
from itertools import islice
import re
import string
import sys


MIN_PHRASE_LENGTH = 2
MAX_PHRASE_LENGTH = 5
NUMBER_TO_REPORT = 10


def window(seq, n=2):
    it = iter(seq)
    result = tuple(islice(it, n))
    if len(result) == n:
        yield result
    for elem in it:
        result = result[1:] + (elem,)
        yield result


def main(argv):
    if len(argv) != 2:
        command = argv[0]
        raise SystemExit(f'Usage: {command} FILE')

    filename = argv[1]
    text = open(filename, errors='replace').read()
    words = list(filter(None, re.split(r'\W+', text.casefold())))

    for n in range(MIN_PHRASE_LENGTH, MAX_PHRASE_LENGTH+1):
        histogram = Counter(window(words, n))
        results = histogram.most_common(NUMBER_TO_REPORT)
        print(f'Top {NUMBER_TO_REPORT} phrases with {n} words:')
        for phrase, count in results:
            joined_phrase = ' '.join(phrase)
            print(f'- {joined_phrase} ({count})')
        print()


if __name__ == '__main__':
    main(sys.argv)