"""
 craps.py

 in class Oct 13 looking at craps

 Jim M et al

 ... we didn't get this debugged or quite finished,
 the first part with craps works, but the statistics
 routines haven't been tested or used with craps yet.

"""

def d6():
  """ Return a random integer from 1 to 6 inclusive.
      >>> x = d6()
      >>> int(x) == x
      True
      >>> 1 <= x <= 6
      True
  """
  from random import randrange
  return randrange(1,7)

def two_d6():
    """ Return sum of two six sided dice. """
    return d6() + d6()

def win_craps():
    """Play one game of craps. Return True if you win."""
    first_roll = two_d6()
    # print "first_roll = ", first_roll
    if first_roll == 2 or first_roll == 3 or first_roll == 12:
        # print "first roll was 2,3,12"
        return False
    elif first_roll == 7 or first_roll == 11:
        # print "first roll was 7,11"
        return True
    else:
        while True:
            next_roll = two_d6()
            # print "next roll is ", next_roll
            if next_roll == first_roll:
                # print "point achieved"
                return True
            elif next_roll == 7:
                # print "crapped out"
                return False

def count_games(n):
    """Play n games of craps. Return number won."""
    count = 0
    for i in range(n):
        if win_craps():
            count = count + 1
    return count

def list_of_count_games(n_game, list_size):
    """Return list of playing n_games rounds of craps."""
    answer = [0] * list_size
    for i in range(list_size):
        answer[i] = count_games(n_game)
    return answer

def mean(numbers):
    """Return mean of a list of numbers.
       >>> mean([1,2,3])
       2.0
    """
    return float(sum(numbers))/len(numbers)

def standard_deviation(numbers):
    """Return standard deviation of list of numbers.
       # >>> 
    """
    from math import sqrt
    average = mean(numbers)
    n = len(numbers)
    square_diffs = [0] * n
    for i in range(n):
        square_diffs[i] = (numbers[i] - average)**2
    return sqrt(mean(square_diffs))

def main():
    print "--- Estimated odds of winning at craps ---"
    number_of_games = input("How many games would you like to simulate? (100) ")
    print "Simulating %i games ..." % number_of_games
    number_won = count_games(number_of_games)
    print "done."
    print "Number of simulated wins : %i" % number_won
    odds = float(number_won)/number_of_games
    print "Estimated odds of winning : %.3f " % odds

if __name__ == "__main__":
    from doctest import testmod
    testmod()
    main()