def getLegalActions(state, ghostIndex):
"""
Ghosts cannot stop, and cannot turn around unless they
reach a dead end, but can turn 90 degrees at intersections.
"""
conf = state.getGhostState(ghostIndex).configuration
possibleActions = Actions.getPossibleActions(conf, state.data.layout.walls)
reverse = Actions.reverseDirection(conf.direction)
if Directions.STOP in possibleActions:
possibleActions.remove(Directions.STOP)
if reverse in possibleActions and len(possibleActions) > 1:
possibleActions.remove(reverse)
return possibleActions
def get_successors(self, state):
"""
Returns successor states, the actions they require, and a cost of 1.
As noted in search.py:
For a given state, this should return a list of triples,
(successor, action, stepCost), where 'successor' is a
successor to the current state, 'action' is the action
required to get there, and 'stepCost' is the incremental
cost of expanding to that successor
"""
successors = []
for action in [
Directions.NORTH, Directions.SOUTH, Directions.EAST,
Directions.WEST
]:
x, y = state
dx, dy = Actions.directionToVector(action)
nextx, nexty = int(x + dx), int(y + dy)
if not self.walls[nextx][nexty]:
nextState = (nextx, nexty)
cost = self.costFn(nextState)
successors.append((nextState, action, cost))
# Bookkeeping for display purposes
self._expanded += 1
if state not in self._visited:
self._visited[state] = True
self._visitedlist.append(state)
return successors
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.scaredTimer > 0
speed = 1
if isScared: speed = 0.5
actionVectors = [Actions.directionToVector( a, speed ) for a in legalActions]
newPositions = [( pos[0]+a[0], pos[1]+a[1] ) for a in actionVectors]
pacmanPosition = state.getPacmanPosition()
# Select best actions given the state
distancesToPacman = [manhattanDistance( pos, pacmanPosition ) for pos in newPositions]
if isScared:
bestScore = max( distancesToPacman )
bestProb = self.prob_scaredFlee
else:
bestScore = min( distancesToPacman )
bestProb = self.prob_attack
bestActions = [action for action, distance in zip( legalActions, distancesToPacman ) if distance == bestScore]
# Construct distribution
dist = util.Counter()
for a in bestActions: dist[a] = bestProb / len(bestActions)
for a in legalActions: dist[a] += ( 1-bestProb ) / len(legalActions)
dist.normalize()
return dist
def applyAction(state, action, ghostIndex):
legal = GhostRules.getLegalActions(state, ghostIndex)
if action not in legal:
raise Exception("Illegal ghost action " + str(action))
ghostState = state.data.agentStates[ghostIndex]
speed = GhostRules.GHOST_SPEED
if ghostState.scaredTimer > 0: speed /= 2.0
vector = Actions.directionToVector(action, speed)
ghostState.configuration = ghostState.configuration.generateSuccessor(vector)
def getCostOfActions(self, actions):
"""
Returns the cost of a particular sequence of actions. If those actions
include an illegal move, return 999999. This is implemented for you.
"""
if actions == None: return 999999
x, y = self.startingPosition
for action in actions:
dx, dy = Actions.directionToVector(action)
x, y = int(x + dx), int(y + dy)
if self.walls[x][y]: return 999999
return len(actions)
def getCostOfActions(self, actions):
"""Returns the cost of a particular sequence of actions. If those actions
include an illegal move, return 999999"""
x, y = self.getStartState()[0]
cost = 0
for action in actions:
# figure out the next state and see whether it's legal
dx, dy = Actions.directionToVector(action)
x, y = int(x + dx), int(y + dy)
if self.walls[x][y]:
return 999999
cost += 1
return cost
def getSuccessors(self, state):
"Returns successor states, the actions they require, and a cost of 1."
successors = []
self._expanded += 1
for direction in [Directions.NORTH, Directions.SOUTH, Directions.EAST, Directions.WEST]:
x,y = state[0]
dx, dy = Actions.directionToVector(direction)
nextx, nexty = int(x + dx), int(y + dy)
if not self.walls[nextx][nexty]:
nextFood = state[1].copy()
nextFood[nextx][nexty] = False
successors.append( ( ((nextx, nexty), nextFood), direction, 1) )
return successors
def get_cost_of_actions(self, actions):
"""
Returns the cost of a particular sequence of actions. If those actions
include an illegal move, return 999999
"""
if actions == None: return 999999
x, y = self.get_start_state()
cost = 0
for action in actions:
# Check figure out the next state and see whether its' legal
dx, dy = Actions.directionToVector(action)
x, y = int(x + dx), int(y + dy)
if self.walls[x][y]: return 999999
cost += self.costFn((x, y))
return cost
def applyAction(state, action):
"""
Edits the state to reflect the results of the action.
"""
legal = PacmanRules.getLegalActions(state)
if action not in legal:
raise Exception("Illegal action " + str(action))
pacmanState = state.data.agentStates[0]
# Update Configuration
vector = Actions.directionToVector(action, PacmanRules.PACMAN_SPEED)
pacmanState.configuration = pacmanState.configuration.generateSuccessor(vector)
# Eat
next = pacmanState.configuration.getPosition()
nearest = nearestPoint(next)
if manhattanDistance(nearest, next) <= 0.5:
# Remove food
PacmanRules.consume(nearest, state)
def getLegalActions(state):
"""
Returns a list of possible actions.
"""
return Actions.getPossibleActions(state.getPacmanState().configuration, state.data.layout.walls)