find_palindromes.py

gistfile1.txt

# Find unintentional palindromes in a text file.

import re
import argparse
from collections import defaultdict

parser = argparse.ArgumentParser(description="Find unintentional palindromes in a text file.")
parser.add_argument("filename", help="The name of the file to look in.")
parser.add_argument("--min", help="Minimum length", default=4)
parser.add_argument("--max", help="Maximum length", default=500)

def scan_file(args):
    with open(args.filename) as fh:
        content = fh.read()

    cleaned = re.sub('[^a-z]', '', content.lower())
    dromes = defaultdict(list)
    for length in range(args.min, args.max):
        for i in range(0, len(cleaned) - length):
            test = cleaned[i:i + length]
            if test == test[::-1]:
                dromes[length].append(test)
        if len(dromes[length]) > 0:
            print length, dromes[length]

if __name__ == "__main__":
    args = parser.parse_args()
    print args
    scan_file(args)