Markov chain text generator in python

markov.py

#!/usr/bin/env python
from __future__ import print_function
 
import argparse
from collections import defaultdict
import os
import random
import sys
 
def main(args):
    result = os.EX_OK
 
    markov_data = defaultdict(list)
    for inputfilename in args.FILE:
        key = ("\n",)*args.sequence_length
        if inputfilename == '-':
            inputfile = sys.stdin
        else:
            inputfile = open(inputfilename, 'r')
 
        for line in inputfile:
            words = line.split(args.delimiter) + ["\n"]
            if len(words):
                for word in words:
                    markov_data[key].append(word)
                    key = key[1:] + (word,)
 
    key = ("\n",)*args.sequence_length
    for x in range(args.output_words):
        word = random.choice(markov_data.get(key, ("\n",)*args.sequence_length))
        key = key[1:] + (word,)
        print(word, end=" ")
 
    return result
 
 
if __name__ == "__main__":
    exit_code = os.EX_OK
    parser = argparse.ArgumentParser()
 
    parser.add_argument('--delimiter', '-d', default=None)
    parser.add_argument('--sequence-length', '-l', type=int, default=2)
    parser.add_argument('--output-words', '-o', type=int, default=1000)
    parser.add_argument("FILE", nargs="*", default=['-'])
 
    parsed_args = parser.parse_args()
 
    try:
        exit_code = main(parsed_args)
    except KeyboardInterrupt:
        pass
    sys.exit(exit_code)