Module pacai.agents.ghost.directional

Classes

class DirectionalGhost (index, prob_attack=0.8, prob_scaredFlee=0.8, **kwargs)

A ghost that prefers to rush Pacman, or flee when scared.

Expand source code

class DirectionalGhost(GhostAgent):
    """
    A ghost that prefers to rush Pacman, or flee when scared.
    """

    def __init__(self, index, prob_attack = 0.8, prob_scaredFlee = 0.8, **kwargs):
        super().__init__(index, **kwargs)

        self.prob_attack = prob_attack
        self.prob_scaredFlee = prob_scaredFlee

    def getDistribution(self, state):
        # Read variables from state.
        ghostState = state.getGhostState(self.index)
        legalActions = state.getLegalActions(self.index)
        pos = state.getGhostPosition(self.index)
        isScared = ghostState.isScared()

        speed = 1
        if (isScared):
            speed = 0.5

        actionVectors = [Actions.directionToVector(action, speed) for action in legalActions]
        newPositions = [(pos[0] + action[0], pos[1] + action[1]) for action in actionVectors]
        pacmanPosition = state.getPacmanPosition()

        # Select best actions given the state.
        distancesToPacman = [distance.manhattan(pos, pacmanPosition) for pos in newPositions]
        if (isScared):
            bestScore = max(distancesToPacman)
            bestProb = self.prob_scaredFlee
        else:
            bestScore = min(distancesToPacman)
            bestProb = self.prob_attack

        zipActions = zip(legalActions, distancesToPacman)
        bestActions = [action for action, distance in zipActions if distance == bestScore]

        # Construct distribution.
        dist = {}

        for action in bestActions:
            dist[action] = float(bestProb) / len(bestActions)

        for action in legalActions:
            if (action not in dist):
                dist[action] = 0
            dist[action] += float(1 - bestProb) / len(legalActions)

        probability.normalize(dist)
        return dist

Ancestors

• GhostAgent
• BaseAgent
• abc.ABC

Static methods

def loadAgent(name, index, args={})

Inherited from: GhostAgent.loadAgent

Load an agent with the given class name. The name can be fully qualified or just the bare class name. If the bare name is given, the class should …

Methods

def final(self, state)

Inherited from: GhostAgent.final

Inform the agent about the result of a game.

def getAction(self, state)

Inherited from: GhostAgent.getAction

The BaseAgent will receive an AbstractGameState, and must return an action from Directions.

def getDistribution(self, state)

Inherited from: GhostAgent.getDistribution

Returns a dictionary encoding a distribution over possible actions.

Expand source code

def getDistribution(self, state):
    # Read variables from state.
    ghostState = state.getGhostState(self.index)
    legalActions = state.getLegalActions(self.index)
    pos = state.getGhostPosition(self.index)
    isScared = ghostState.isScared()

    speed = 1
    if (isScared):
        speed = 0.5

    actionVectors = [Actions.directionToVector(action, speed) for action in legalActions]
    newPositions = [(pos[0] + action[0], pos[1] + action[1]) for action in actionVectors]
    pacmanPosition = state.getPacmanPosition()

    # Select best actions given the state.
    distancesToPacman = [distance.manhattan(pos, pacmanPosition) for pos in newPositions]
    if (isScared):
        bestScore = max(distancesToPacman)
        bestProb = self.prob_scaredFlee
    else:
        bestScore = min(distancesToPacman)
        bestProb = self.prob_attack

    zipActions = zip(legalActions, distancesToPacman)
    bestActions = [action for action, distance in zipActions if distance == bestScore]

    # Construct distribution.
    dist = {}

    for action in bestActions:
        dist[action] = float(bestProb) / len(bestActions)

    for action in legalActions:
        if (action not in dist):
            dist[action] = 0
        dist[action] += float(1 - bestProb) / len(legalActions)

    probability.normalize(dist)
    return dist

def observationFunction(self, state)

Inherited from: GhostAgent.observationFunction

Make an observation on the state of the game. Called once for each round of the game.

def registerInitialState(self, state)

Inherited from: GhostAgent.registerInitialState

Inspect the starting state.