gridworld.py

# gridworld.py
# ------------
# Licensing Information:  You are free to use or extend these projects for
# educational purposes provided that (1) you do not distribute or publish
# solutions, (2) you retain this notice, and (3) you provide clear
# attribution to UC Berkeley, including a link to http://ai.berkeley.edu.
# 
# Attribution Information: The Pacman AI projects were developed at UC Berkeley.
# The core projects and autograders were primarily created by John DeNero
# (denero@cs.berkeley.edu) and Dan Klein (klein@cs.berkeley.edu).
# Student side autograding was added by Brad Miller, Nick Hay, and
# Pieter Abbeel (pabbeel@cs.berkeley.edu).


import random
import sys
import mdp
import environment
import util
import optparse

class Gridworld(mdp.MarkovDecisionProcess):
    """
      Gridworld
    """
    def __init__(self, grid):
        # layout
        if type(grid) == type([]): grid = makeGrid(grid)
        self.grid = grid

        # parameters
        self.livingReward = 0.0
        self.noise = 0.2

    def setLivingReward(self, reward):
        """
        The (negative) reward for exiting "normal" states.

        Note that in the R+N text, this reward is on entering
        a state and therefore is not clearly part of the state's
        future rewards.
        """
        self.livingReward = reward

    def setNoise(self, noise):
        """
        The probability of moving in an unintended direction.
        """
        self.noise = noise


    def getPossibleActions(self, state):
        """
        Returns list of valid actions for 'state'.

        Note that you can request moves into walls and
        that "exit" states transition to the terminal
        state under the special action "done".
        """
        if state == self.grid.terminalState:
            return ()
        x,y = state
        if type(self.grid[x][y]) == int:
            return ('exit',)
        return ('north','west','south','east')

    def getStates(self):
        """
        Return list of all states.
        """
        # The true terminal state.
        states = [self.grid.terminalState]
        for x in range(self.grid.width):
            for y in range(self.grid.height):
                if self.grid[x][y] != '#':
                    state = (x,y)
                    states.append(state)
        return states

    def getReward(self, state, action, nextState):
        """
        Get reward for state, action, nextState transition.

        Note that the reward depends only on the state being
        departed (as in the R+N book examples, which more or
        less use this convention).
        """
        if state == self.grid.terminalState:
            return 0.0
        x, y = state
        cell = self.grid[x][y]
        if type(cell) == int or type(cell) == float:
            return cell
        return self.livingReward

    def getStartState(self):
        for x in range(self.grid.width):
            for y in range(self.grid.height):
                if self.grid[x][y] == 'S':
                    return (x, y)
        raise 'Grid has no start state'

    def isTerminal(self, state):
        """
        Only the TERMINAL_STATE state is *actually* a terminal state.
        The other "exit" states are technically non-terminals with
        a single action "exit" which leads to the true terminal state.
        This convention is to make the grids line up with the examples
        in the R+N textbook.
        """
        return state == self.grid.terminalState


    def getTransitionStatesAndProbs(self, state, action):
        """
        Returns list of (nextState, prob) pairs
        representing the states reachable
        from 'state' by taking 'action' along
        with their transition probabilities.
        """

        if action not in self.getPossibleActions(state):
            raise "Illegal action!"

        if self.isTerminal(state):
            return []

        x, y = state

        if type(self.grid[x][y]) == int or type(self.grid[x][y]) == float:
            termState = self.grid.terminalState
            return [(termState, 1.0)]

        successors = []

        northState = (self.__isAllowed(y+1,x) and (x,y+1)) or state
        westState = (self.__isAllowed(y,x-1) and (x-1,y)) or state
        southState = (self.__isAllowed(y-1,x) and (x,y-1)) or state
        eastState = (self.__isAllowed(y,x+1) and (x+1,y)) or state

        if action == 'north' or action == 'south':
            if action == 'north':
                successors.append((northState,1-self.noise))
            else:
                successors.append((southState,1-self.noise))

            massLeft = self.noise
            successors.append((westState,massLeft/2.0))
            successors.append((eastState,massLeft/2.0))

        if action == 'west' or action == 'east':
            if action == 'west':
                successors.append((westState,1-self.noise))
            else:
                successors.append((eastState,1-self.noise))

            massLeft = self.noise
            successors.append((northState,massLeft/2.0))
            successors.append((southState,massLeft/2.0))

        successors = self.__aggregate(successors)

        return successors

    def __aggregate(self, statesAndProbs):
        counter = util.Counter()
        for state, prob in statesAndProbs:
            counter[state] += prob
        newStatesAndProbs = []
        for state, prob in list(counter.items()):
            newStatesAndProbs.append((state, prob))
        return newStatesAndProbs

    def __isAllowed(self, y, x):
        if y < 0 or y >= self.grid.height: return False
        if x < 0 or x >= self.grid.width: return False
        return self.grid[x][y] != '#'

class GridworldEnvironment(environment.Environment):

    def __init__(self, gridWorld):
        self.gridWorld = gridWorld
        self.reset()

    def getCurrentState(self):
        return self.state

    def getPossibleActions(self, state):
        return self.gridWorld.getPossibleActions(state)

    def doAction(self, action):
        state = self.getCurrentState()
        (nextState, reward) = self.getRandomNextState(state, action)
        self.state = nextState
        return (nextState, reward)

    def getRandomNextState(self, state, action, randObj=None):
        rand = -1.0
        if randObj is None:
            rand = random.random()
        else:
            rand = randObj.random()
        sum = 0.0
        successors = self.gridWorld.getTransitionStatesAndProbs(state, action)
        for nextState, prob in successors:
            sum += prob
            if sum > 1.0:
                raise 'Total transition probability more than one; sample failure.'
            if rand < sum:
                reward = self.gridWorld.getReward(state, action, nextState)
                return (nextState, reward)
        raise 'Total transition probability less than one; sample failure.'

    def reset(self):
        self.state = self.gridWorld.getStartState()

class Grid:
    """
    A 2-dimensional array of immutables backed by a list of lists.  Data is accessed
    via grid[x][y] where (x,y) are cartesian coordinates with x horizontal,
    y vertical and the origin (0,0) in the bottom left corner.

    The __str__ method constructs an output that is oriented appropriately.
    """
    def __init__(self, width, height, initialValue=' '):
        self.width = width
        self.height = height
        self.data = [[initialValue for y in range(height)] for x in range(width)]
        self.terminalState = 'TERMINAL_STATE'

    def __getitem__(self, i):
        return self.data[i]

    def __setitem__(self, key, item):
        self.data[key] = item

    def __eq__(self, other):
        if other == None: return False
        return self.data == other.data

    def __hash__(self):
        return hash(self.data)

    def copy(self):
        g = Grid(self.width, self.height)
        g.data = [x[:] for x in self.data]
        return g

    def deepCopy(self):
        return self.copy()

    def shallowCopy(self):
        g = Grid(self.width, self.height)
        g.data = self.data
        return g

    def _getLegacyText(self):
        t = [[self.data[x][y] for x in range(self.width)] for y in range(self.height)]
        t.reverse()
        return t

    def __str__(self):
        return str(self._getLegacyText())

def makeGrid(gridString):
    width, height = len(gridString[0]), len(gridString)
    grid = Grid(width, height)
    for ybar, line in enumerate(gridString):
        y = height - ybar - 1
        for x, el in enumerate(line):
            grid[x][y] = el
    return grid

def getCliffGrid():
    grid = [[' ',' ',' ',' ',' '],
            ['S',' ',' ',' ',10],
            [-100,-100, -100, -100, -100]]
    return Gridworld(makeGrid(grid))

def getCliffGrid2():
    grid = [[' ',' ',' ',' ',' '],
            [8,'S',' ',' ',10],
            [-100,-100, -100, -100, -100]]
    return Gridworld(grid)

def getDiscountGrid():
    grid = [[' ',' ',' ',' ',' '],
            [' ','#',' ',' ',' '],
            [' ','#', 1,'#', 10],
            ['S',' ',' ',' ',' '],
            [-10,-10, -10, -10, -10]]
    return Gridworld(grid)

def getBridgeGrid():
    grid = [[ '#',-100, -100, -100, -100, -100, '#'],
            [   1, 'S',  ' ',  ' ',  ' ',  ' ',  10],
            [ '#',-100, -100, -100, -100, -100, '#']]
    return Gridworld(grid)

def getBookGrid():
    grid = [[' ',' ',' ',+1],
            [' ','#',' ',-1],
            ['S',' ',' ',' ']]
    return Gridworld(grid)

def getMazeGrid():
    grid = [[' ',' ',' ',+1],
            ['#','#',' ','#'],
            [' ','#',' ',' '],
            [' ','#','#',' '],
            ['S',' ',' ',' ']]
    return Gridworld(grid)



def getUserAction(state, actionFunction):
    """
    Get an action from the user (rather than the agent).

    Used for debugging and lecture demos.
    """
    import graphicsUtils
    action = None
    while True:
        keys = graphicsUtils.wait_for_keys()
        if 'Up' in keys: action = 'north'
        if 'Down' in keys: action = 'south'
        if 'Left' in keys: action = 'west'
        if 'Right' in keys: action = 'east'
        if 'q' in keys: sys.exit(0)
        if action == None: continue
        break
    actions = actionFunction(state)
    if action not in actions:
        action = actions[0]
    return action

def printString(x): print(x)

def runEpisode(agent, environment, discount, decision, display, message, pause, episode):
    returns = 0
    totalDiscount = 1.0
    environment.reset()
    if 'startEpisode' in dir(agent): agent.startEpisode()
    message("BEGINNING EPISODE: "+str(episode)+"\n")
    while True:

        # DISPLAY CURRENT STATE
        state = environment.getCurrentState()
        display(state)
        pause()

        # END IF IN A TERMINAL STATE
        actions = environment.getPossibleActions(state)
        if len(actions) == 0:
            message("EPISODE "+str(episode)+" COMPLETE: RETURN WAS "+str(returns)+"\n")
            return returns

        # GET ACTION (USUALLY FROM AGENT)
        action = decision(state)
        if action == None:
            raise 'Error: Agent returned None action'

        # EXECUTE ACTION
        nextState, reward = environment.doAction(action)
        message("Started in state: "+str(state)+
                "\nTook action: "+str(action)+
                "\nEnded in state: "+str(nextState)+
                "\nGot reward: "+str(reward)+"\n")
        # UPDATE LEARNER
        if 'observeTransition' in dir(agent):
            agent.observeTransition(state, action, nextState, reward)

        returns += reward * totalDiscount
        totalDiscount *= discount

    if 'stopEpisode' in dir(agent):
        agent.stopEpisode()

def parseOptions():
    optParser = optparse.OptionParser()
    optParser.add_option('-d', '--discount',action='store',
                         type='float',dest='discount',default=0.9,
                         help='Discount on future (default %default)')
    optParser.add_option('-r', '--livingReward',action='store',
                         type='float',dest='livingReward',default=0.0,
                         metavar="R", help='Reward for living for a time step (default %default)')
    optParser.add_option('-n', '--noise',action='store',
                         type='float',dest='noise',default=0.2,
                         metavar="P", help='How often action results in ' +
                         'unintended direction (default %default)' )
    optParser.add_option('-e', '--epsilon',action='store',
                         type='float',dest='epsilon',default=0.3,
                         metavar="E", help='Chance of taking a random action in q-learning (default %default)')
    optParser.add_option('-l', '--learningRate',action='store',
                         type='float',dest='learningRate',default=0.5,
                         metavar="P", help='TD learning rate (default %default)' )
    optParser.add_option('-i', '--iterations',action='store',
                         type='int',dest='iters',default=10,
                         metavar="K", help='Number of rounds of value iteration (default %default)')
    optParser.add_option('-k', '--episodes',action='store',
                         type='int',dest='episodes',default=1,
                         metavar="K", help='Number of epsiodes of the MDP to run (default %default)')
    optParser.add_option('-g', '--grid',action='store',
                         metavar="G", type='string',dest='grid',default="BookGrid",
                         help='Grid to use (case sensitive; options are BookGrid, BridgeGrid, CliffGrid, MazeGrid, default %default)' )
    optParser.add_option('-w', '--windowSize', metavar="X", type='int',dest='gridSize',default=150,
                         help='Request a window width of X pixels *per grid cell* (default %default)')
    optParser.add_option('-a', '--agent',action='store', metavar="A",
                         type='string',dest='agent',default="random",
                         help='Agent type (options are \'random\', \'value\' and \'q\', default %default)')
    optParser.add_option('-t', '--text',action='store_true',
                         dest='textDisplay',default=False,
                         help='Use text-only ASCII display')
    optParser.add_option('-p', '--pause',action='store_true',
                         dest='pause',default=False,
                         help='Pause GUI after each time step when running the MDP')
    optParser.add_option('-q', '--quiet',action='store_true',
                         dest='quiet',default=False,
                         help='Skip display of any learning episodes')
    optParser.add_option('-s', '--speed',action='store', metavar="S", type=float,
                         dest='speed',default=1.0,
                         help='Speed of animation, S > 1.0 is faster, 0.0 < S < 1.0 is slower (default %default)')
    optParser.add_option('-m', '--manual',action='store_true',
                         dest='manual',default=False,
                         help='Manually control agent')
    optParser.add_option('-v', '--valueSteps',action='store_true' ,default=False,
                         help='Display each step of value iteration')

    opts, args = optParser.parse_args()

    if opts.manual and opts.agent != 'q':
        print('## Disabling Agents in Manual Mode (-m) ##')
        opts.agent = None

    # MANAGE CONFLICTS
    if opts.textDisplay or opts.quiet:
    # if opts.quiet:
        opts.pause = False
        # opts.manual = False

    if opts.manual:
        opts.pause = True

    return opts


if __name__ == '__main__':

    opts = parseOptions()

    ###########################
    # GET THE GRIDWORLD
    ###########################

    import gridworld
    mdpFunction = getattr(gridworld, "get"+opts.grid)
    mdp = mdpFunction()
    mdp.setLivingReward(opts.livingReward)
    mdp.setNoise(opts.noise)
    env = gridworld.GridworldEnvironment(mdp)


    ###########################
    # GET THE DISPLAY ADAPTER
    ###########################

    import textGridworldDisplay
    display = textGridworldDisplay.TextGridworldDisplay(mdp)
    if not opts.textDisplay:
        import graphicsGridworldDisplay
        display = graphicsGridworldDisplay.GraphicsGridworldDisplay(mdp, opts.gridSize, opts.speed)
    try:
        display.start()
    except KeyboardInterrupt:
        sys.exit(0)

    ###########################
    # GET THE AGENT
    ###########################

    import valueIterationAgents, qlearningAgents
    a = None
    if opts.agent == 'value':
        a = valueIterationAgents.ValueIterationAgent(mdp, opts.discount, opts.iters)
    elif opts.agent == 'q':
        #env.getPossibleActions, opts.discount, opts.learningRate, opts.epsilon
        #simulationFn = lambda agent, state: simulation.GridworldSimulation(agent,state,mdp)
        gridWorldEnv = GridworldEnvironment(mdp)
        actionFn = lambda state: mdp.getPossibleActions(state)
        qLearnOpts = {'gamma': opts.discount,
                      'alpha': opts.learningRate,
                      'epsilon': opts.epsilon,
                      'actionFn': actionFn}
        a = qlearningAgents.QLearningAgent(**qLearnOpts)
    elif opts.agent == 'random':
        # # No reason to use the random agent without episodes
        if opts.episodes == 0:
            opts.episodes = 10
        class RandomAgent:
            def getAction(self, state):
                return random.choice(mdp.getPossibleActions(state))
            def getValue(self, state):
                return 0.0
            def getQValue(self, state, action):
                return 0.0
            def getPolicy(self, state):
                "NOTE: 'random' is a special policy value; don't use it in your code."
                return 'random'
            def update(self, state, action, nextState, reward):
                pass
        a = RandomAgent()
    else:
        if not opts.manual: raise 'Unknown agent type: '+opts.agent


    ###########################
    # RUN EPISODES
    ###########################
    # DISPLAY Q/V VALUES BEFORE SIMULATION OF EPISODES
    try:
        if not opts.manual and opts.agent == 'value':
            if opts.valueSteps:
                for i in range(opts.iters):
                    tempAgent = valueIterationAgents.ValueIterationAgent(mdp, opts.discount, i)
                    display.displayValues(tempAgent, message = "VALUES AFTER "+str(i)+" ITERATIONS")
                    display.pause()

            display.displayValues(a, message = "VALUES AFTER "+str(opts.iters)+" ITERATIONS")
            display.pause()
            display.displayQValues(a, message = "Q-VALUES AFTER "+str(opts.iters)+" ITERATIONS")
            display.pause()
    except KeyboardInterrupt:
        sys.exit(0)



    # FIGURE OUT WHAT TO DISPLAY EACH TIME STEP (IF ANYTHING)
    displayCallback = lambda x: None
    if not opts.quiet:
        if opts.manual and opts.agent == None:
            displayCallback = lambda state: display.displayNullValues(state)
        else:
            if opts.agent == 'random': displayCallback = lambda state: display.displayValues(a, state, "CURRENT VALUES")
            if opts.agent == 'value': displayCallback = lambda state: display.displayValues(a, state, "CURRENT VALUES")
            if opts.agent == 'q': displayCallback = lambda state: display.displayQValues(a, state, "CURRENT Q-VALUES")

    messageCallback = lambda x: printString(x)
    if opts.quiet:
        messageCallback = lambda x: None

    # FIGURE OUT WHETHER TO WAIT FOR A KEY PRESS AFTER EACH TIME STEP
    pauseCallback = lambda : None
    if opts.pause:
        pauseCallback = lambda : display.pause()

    # FIGURE OUT WHETHER THE USER WANTS MANUAL CONTROL (FOR DEBUGGING AND DEMOS)
    if opts.manual:
        decisionCallback = lambda state : getUserAction(state, mdp.getPossibleActions)
    else:
        decisionCallback = a.getAction

    # RUN EPISODES
    if opts.episodes > 0:
        print()
        print("RUNNING", opts.episodes, "EPISODES")
        print()
    returns = 0
    for episode in range(1, opts.episodes+1):
        returns += runEpisode(a, env, opts.discount, decisionCallback, displayCallback, messageCallback, pauseCallback, episode)
    if opts.episodes > 0:
        print()
        print("AVERAGE RETURNS FROM START STATE: "+str((returns+0.0) / opts.episodes))
        print()
        print()

    # DISPLAY POST-LEARNING VALUES / Q-VALUES
    if opts.agent == 'q' and not opts.manual:
        try:
            display.displayQValues(a, message = "Q-VALUES AFTER "+str(opts.episodes)+" EPISODES")
            display.pause()
            display.displayValues(a, message = "VALUES AFTER "+str(opts.episodes)+" EPISODES")
            display.pause()
        except KeyboardInterrupt:
            sys.exit(0)