markov.py

import random
from collections import defaultdict

def get_words(fname='fyad.txt'):
    with open(fname) as f:
        return f.read().split()

def triplets(words):
    for i in xrange(len(words) - 2):
        yield (words[i], words[i+1], words[i+2])

def chain(words):
    d = defaultdict(list)
    for w1, w2, w3 in triplets(words):
        pair = (w1, w2)
        d[pair].append(w3)
    return d