hog.py

"""The Game of Hog."""

from dice import six_sided, four_sided, make_test_dice
from ucb import main, trace, interact

GOAL_SCORE = 100  # The goal of Hog is to score 100 points.

######################
# Phase 1: Simulator #
######################


def roll_dice(num_rolls, dice=six_sided):
    """Simulate rolling the DICE exactly NUM_ROLLS > 0 times. Return the sum of
    the outcomes unless any of the outcomes is 1. In that case, return 1.

    num_rolls:  The number of dice rolls that will be made.
    dice:       A function that simulates a single dice roll outcome.
    """
    # These assert statements ensure that num_rolls is a positive integer.
    assert type(num_rolls) == int, 'num_rolls must be an integer.'
    assert num_rolls > 0, 'Must roll at least once.'

    n = num_rolls
    prev = 0
    curr = 0
    while (n > 0):
        prev, curr = curr, curr + dice()
        n = n - 1
        if(curr == prev + 1):
            curr = 1
            while(n > 0):
                dice()
                n = n - 1
            return curr
    return curr



def free_bacon(score):
    """Return the points scored from rolling 0 dice (Free Bacon).

    score:  The opponent's current score.
    """
    assert score < 100, 'The game should be over.'


    left, right = score // 10, score % 10
    if(left > right):
        return right + 1
    else:
        return left + 1



def take_turn(num_rolls, opponent_score, dice=six_sided):
    """Simulate a turn rolling NUM_ROLLS dice, which may be 0 (Free Bacon).
    Return the points scored for the turn by the current player.

    num_rolls:       The number of dice rolls that will be made.
    opponent_score:  The total score of the opponent.
    dice:            A function that simulates a single dice roll outcome.
    """
    # Leave these assert statements here; they help check for errors.
    assert type(num_rolls) == int, 'num_rolls must be an integer.'
    assert num_rolls >= 0, 'Cannot roll a negative number of dice in take_turn.'
    assert num_rolls <= 10, 'Cannot roll more than 10 dice.'
    assert opponent_score < 100, 'The game should be over.'

    if(num_rolls == 0):
        return free_bacon(opponent_score)
    else:
        return roll_dice(num_rolls,dice)



def is_swap(player_score, opponent_score):
    """
    Return whether the two scores should be swapped
    """

    p, o = player_score, opponent_score
    while(p != 0 and o != 0):
        if(p % 10 == o % 10):
            return True
        p, o = p // 10, o // 10
    return False



def other(player):
    """Return the other player, for a player PLAYER numbered 0 or 1.

    >>> other(0)
    1
    >>> other(1)
    0
    """
    return 1 - player


def silence(score0, score1):
    """Announce nothing (see Phase 2)."""
    return silence


def play(strategy0, strategy1, score0=0, score1=0, dice=six_sided,
         goal=GOAL_SCORE, say=silence):
    """Simulate a game and return the final scores of both players, with Player
    0's score first, and Player 1's score second.

    A strategy is a function that takes two total scores as arguments (the
    current player's score, and the opponent's score), and returns a number of
    dice that the current player will roll this turn.

    strategy0:  The strategy function for Player 0, who plays first.
    strategy1:  The strategy function for Player 1, who plays second.
    score0:     Starting score for Player 0
    score1:     Starting score for Player 1
    dice:       A function of zero arguments that simulates a dice roll.
    goal:       The game ends and someone wins when this score is reached.
    say:        The commentary function to call at the end of the first turn.
    """
    player = 0  # Which player is about to take a turn, 0 (first) or 1 (second)


    score0 = score0 + take_turn(strategy0(score0,score1),score1,dice)
    if(is_swap(score0,score1)):
        score0, score1 = score1, score0
    x = say(score0,score1)

    while(score0 < goal and score1 < goal):
        score1 = score1 + take_turn(strategy1(score1,score0),score0,dice)
        if(is_swap(score1,score0)):
            score0, score1 = score1, score0
        x = x(score0,score1)
        if(score0 >= goal or score1 >= goal):
            break
        score0 = score0 + take_turn(strategy0(score0,score1),score1,dice)
        if(is_swap(score0,score1)):
            score0, score1 = score1, score0
        x = x(score0,score1)

    return score0, score1


#######################
# Phase 2: Commentary #
#######################


def say_scores(score0, score1):
    """A commentary function that announces the score for each player."""
    print("Player 0 now has", score0, "and Player 1 now has", score1)
    return say_scores

def announce_lead_changes(previous_leader=None):
    """Return a commentary function that announces lead changes.

    >>> f0 = announce_lead_changes()
    >>> f1 = f0(5, 0)
    Player 0 takes the lead by 5
    >>> f2 = f1(5, 12)
    Player 1 takes the lead by 7
    >>> f3 = f2(8, 12)
    >>> f4 = f3(8, 13)
    >>> f5 = f4(15, 13)
    Player 0 takes the lead by 2
    """
    def say(score0, score1):
        if score0 > score1:
            leader = 0
        elif score1 > score0:
            leader = 1
        else:
            leader = None
        if leader != None and leader != previous_leader:
            print('Player', leader, 'takes the lead by', abs(score0 - score1))
        return announce_lead_changes(leader)
    return say

def both(f, g):
    """Return a commentary function that says what f says, then what g says.

    NOTE: the following game is not possible under the rules, it's just
    an example for the sake of the doctest

    >>> h0 = both(say_scores, announce_lead_changes())
    >>> h1 = h0(10, 0)
    Player 0 now has 10 and Player 1 now has 0
    Player 0 takes the lead by 10
    >>> h2 = h1(10, 6)
    Player 0 now has 10 and Player 1 now has 6
    >>> h3 = h2(6, 17)
    Player 0 now has 6 and Player 1 now has 17
    Player 1 takes the lead by 11
    """
    def say(score0, score1):
        return both(f(score0, score1), g(score0, score1))
    return say


def announce_highest(who, previous_high=0, previous_score=0):
    """Return a commentary function that announces when WHO's score
    increases by more than ever before in the game.

    NOTE: the following game is not possible under the rules, it's just
    an example for the sake of the doctest

    >>> f0 = announce_highest(1) # Only announce Player 1 score gains
    >>> f1 = f0(12, 0)
    >>> f2 = f1(12, 11)
    11 point(s)! That's the biggest gain yet for Player 1
    >>> f3 = f2(20, 11)
    >>> f4 = f3(13, 20)
    >>> f5 = f4(20, 35)
    15 point(s)! That's the biggest gain yet for Player 1
    >>> f6 = f5(20, 47) # Player 1 gets 12 points; not enough for a new high
    >>> f7 = f6(21, 47)
    >>> f8 = f7(21, 77)
    30 point(s)! That's the biggest gain yet for Player 1
    >>> f9 = f8(77, 22) # Swap!
    >>> f10 = f9(33, 77) # Swap!
    55 point(s)! That's the biggest gain yet for Player 1
    """
    assert who == 0 or who == 1, 'The who argument should indicate a player.'


    def lala(s0,s1):
        if(who == 0):
            x = s0
        else:
            x = s1
        if(x - previous_score > previous_high):
            print(x - previous_score, 'point(s)! That\'s the biggest gain yet for Player',who)
            return announce_highest(who,x - previous_score,x)
        return announce_highest(who,previous_high,x)
    return lala



#######################
# Phase 3: Strategies #
#######################


def always_roll(n):
    """Return a strategy that always rolls N dice.

    A strategy is a function that takes two total scores as arguments (the
    current player's score, and the opponent's score), and returns a number of
    dice that the current player will roll this turn.

    >>> strategy = always_roll(5)
    >>> strategy(0, 0)
    5
    >>> strategy(99, 99)
    5
    """
    def strategy(score, opponent_score):
        return n
    return strategy


def make_averaged(fn, num_samples=1000):
    """Return a function that returns the average value of FN when called.

    To implement this function, you will have to use *args syntax, a new Python
    feature introduced in this project.  See the project description.

    >>> dice = make_test_dice(4, 2, 5, 1)
    >>> averaged_dice = make_averaged(dice, 1000)
    >>> averaged_dice()
    3.0
    """


    def mom(*args):
        x, avg = num_samples, 0
        while(x > 0):
            avg = avg + fn(*args)
            x = x - 1
        return avg / num_samples
    return mom



def max_scoring_num_rolls(dice=six_sided, num_samples=1000):
    """Return the number of dice (1 to 10) that gives the highest average turn
    score by calling roll_dice with the provided DICE over NUM_SAMPLES times.
    Assume that the dice always return positive outcomes.

    >>> dice = make_test_dice(1, 6)
    >>> max_scoring_num_rolls(dice)
    1
    """


    x, roll, prev, score = 1, 1, 0, 0
    la = make_averaged(roll_dice,num_samples)
    while x <= 10:
        score = la(x,dice)
        if score > prev:
            prev = score
            roll = x
        x = x + 1
    return roll



def winner(strategy0, strategy1):
    """Return 0 if strategy0 wins against strategy1, and 1 otherwise."""
    score0, score1 = play(strategy0, strategy1)
    if score0 > score1:
        return 0
    else:
        return 1


def average_win_rate(strategy, baseline=always_roll(4)):
    """Return the average win rate of STRATEGY against BASELINE. Averages the
    winrate when starting the game as player 0 and as player 1.
    """
    win_rate_as_player_0 = 1 - make_averaged(winner)(strategy, baseline)
    win_rate_as_player_1 = make_averaged(winner)(baseline, strategy)

    return (win_rate_as_player_0 + win_rate_as_player_1) / 2


def run_experiments():
    """Run a series of strategy experiments and report results."""
    if False:  # Change to False when done finding max_scoring_num_rolls
        six_sided_max = max_scoring_num_rolls(six_sided)
        print('Max scoring num rolls for six-sided dice:', six_sided_max)

    if False:  # Change to True to test always_roll(8)
        print('always_roll(6) win rate:', average_win_rate(always_roll(6)))

    if False:  # Change to True to test bacon_strategy
        print('bacon_strategy win rate:', average_win_rate(bacon_strategy))

    if True:  # Change to True to test swap_strategy
        print('swap_strategy win rate:', average_win_rate(swap_strategy))

    if False:  # Change to True to test final_strategy
        print('final_strategy win rate:', average_win_rate(final_strategy))




def bacon_strategy(score, opponent_score, margin=8, num_rolls=4):
    """This strategy rolls 0 dice if that gives at least MARGIN points, and
    rolls NUM_ROLLS otherwise.
    """

    if free_bacon(opponent_score) >= margin:
        return 0
    return num_rolls



def swap_strategy(score, opponent_score, margin=8, num_rolls=4):
    """This strategy rolls 0 dice when it triggers a beneficial swap. It also
    rolls 0 dice if it gives at least MARGIN points and does not trigger a
    non-beneficial swap. Otherwise, it rolls NUM_ROLLS.
    """

    if free_bacon(opponent_score) >= margin and not(is_swap(score + free_bacon(opponent_score),opponent_score)):
        return 0
    elif free_bacon(opponent_score) >= margin and (score + free_bacon(opponent_score)) <= opponent_score:
        return 0
    elif is_swap(score + free_bacon(opponent_score),opponent_score) and opponent_score > score + free_bacon(opponent_score):
        return 0
    return num_rolls



def final_strategy(score, opponent_score):
    """Write a brief description of your final strategy.

    *** YOUR DESCRIPTION HERE ***
    """

    return 4  # Replace this statement



##########################
# Command Line Interface #
##########################



@main
def run(*args):
    """Read in the command-line argument and calls corresponding functions.

    This function uses Python syntax/techniques not yet covered in this course.
    """
    import argparse
    parser = argparse.ArgumentParser(description="Play Hog")
    parser.add_argument('--run_experiments', '-r', action='store_true',
                        help='Runs strategy experiments')

    args = parser.parse_args()

    if args.run_experiments:
        run_experiments()