text: #!/usr/bin/python -tt
  # Copyright 2010 Google Inc.
  # Licensed under the Apache License, Version 2.0
  # http://www.apache.org/licenses/LICENSE-2.0
  
  # Google's Python Class
  # http://code.google.com/edu/languages/google-python-class/
  
  """Mimic pyquick exercise -- optional extra exercise.
  Google's Python Class
  
  Read in the file specified on the command line.
  Do a simple split() on whitespace to obtain all the words in the file.
  Rather than read the file line by line, it's easier to read
  it into one giant string and split it once.
  
  Build a "mimic" dict that maps each word that appears in the file
  to a list of all the words that immediately follow that word in the file.
  The list of words can be in any order and should include
  duplicates. So for example the key "and" might have the list
  ["then", "best", "then", "after", ...] listing
  all the words which came after "and" in the text.
  We'll say that the empty string is what comes before
  the first word in the file.
  
  With the mimic dict, it's fairly easy to emit random
  text that mimics the original. Print a word, then look
  up what words might come next and pick one at random as
  the next word.
  Use the empty string as the first word to prime things.
  If we ever get stuck with a word that is not in the dict,
  go back to the empty string to keep things moving.
  
  Note: the standard python module 'random' includes a
  random.choice(list) method which picks a random element
  from a non-empty list.
  
  For fun, feed your program to itself as input.
  Could work on getting it to put in linebreaks around 70
  columns, so the output looks better.
  
  """
  
  import random
  import sys
  
  from collections import Counter
  
  def mimic_dict(filename):
    """Returns mimic dict mapping each word to list of words which follow it."""
   
    mimic_dict = {}
    f = open(filename, 'r')
    text = f.read()
    f.close()
    words = text.split()
    prev = ''
    for word in words:
      if not prev in mimic_dict:
        mimic_dict[prev] = [word]
        #print [word], mimic_dict[prev]
      else:
        mimic_dict[prev].append(word)
    return mimic_dict
  
  #print mimic_dict('alice2.txt')
  
  def print_mimic(mimic_dict, word):
    """Given mimic dict and start word, prints 200 random words."""
    
    for i in range (200):
      print word, 
      nexts = mimic_dict.get(word)
      if not nexts:
        nexts = mimic_dict['']
      word = random.choice(nexts)
  '''
  next_word = random.choice(mimic_words[word])
  if next_word in mimic_words: 
    output += next_word + " "
  else: next_word = " "
  word = next_word
  '''
  #print word
  #print mimic_words[next_word]
  
  
  # Provided main(), calls mimic_dict() and mimic()
  def main():
    if len(sys.argv) != 2:
      print 'usage: ./mimic.py file-to-read'
      sys.exit(1)
  
    dict = mimic_dict(sys.argv[1])
    print_mimic(dict, '')
  
  
  if __name__ == '__main__':
    main()
  