# Dead-end avoidance team for CS470 Assignment 3.
from captureAgents import CaptureAgent
import random
import util
from game import Directions
from util import nearestPoint
def createTeam(firstIndex, secondIndex, isRed,
first='DeadEndOffensiveAgent',
second='PatrolDefensiveAgent'):
return [eval(first)(firstIndex), eval(second)(secondIndex)]
def computeDeadEndDepths(gameState):
"""Return a map from legal cells to their peeled dead-end depth."""
walls = gameState.getWalls()
width = walls.width
height = walls.height
legal = []
degree = {}
neighbors = {}
for x in range(width):
for y in range(height):
if walls[x][y]:
continue
pos = (x, y)
legal.append(pos)
nbrs = []
for dx, dy in ((1, 0), (-1, 0), (0, 1), (0, -1)):
nx, ny = x + dx, y + dy
if 0 <= nx < width and 0 <= ny < height and not walls[nx][ny]:
nbrs.append((nx, ny))
neighbors[pos] = nbrs
degree[pos] = len(nbrs)
queue = []
depths = {}
head = 0
for pos in legal:
if degree[pos] <= 1:
depths[pos] = 1
queue.append(pos)
removed = set()
while head < len(queue):
pos = queue[head]
head += 1
if pos in removed:
continue
removed.add(pos)
for nbr in neighbors[pos]:
if nbr in removed:
continue
degree[nbr] -= 1
if degree[nbr] <= 1 and nbr not in depths:
depths[nbr] = depths[pos] + 1
queue.append(nbr)
return depths
class ReflexCaptureAgent(CaptureAgent):
def registerInitialState(self, gameState):
self.start = gameState.getAgentPosition(self.index)
self.width = gameState.data.layout.width
self.height = gameState.data.layout.height
CaptureAgent.registerInitialState(self, gameState)
self.homeEntries = self.getHomeEntries(gameState)
self.deadEndDepths = computeDeadEndDepths(gameState)
def chooseAction(self, gameState):
actions = gameState.getLegalActions(self.index)
values = [self.evaluate(gameState, action) for action in actions]
bestValue = max(values)
bestActions = [a for a, v in zip(actions, values) if v == bestValue]
if Directions.STOP in bestActions and len(bestActions) > 1:
bestActions.remove(Directions.STOP)
return random.choice(bestActions)
def getSuccessor(self, gameState, action):
successor = gameState.generateSuccessor(self.index, action)
pos = successor.getAgentState(self.index).getPosition()
if pos != nearestPoint(pos):
return successor.generateSuccessor(self.index, action)
return successor
def evaluate(self, gameState, action):
return self.getFeatures(gameState, action) * self.getWeights(gameState, action)
def getFeatures(self, gameState, action):
features = util.Counter()
successor = self.getSuccessor(gameState, action)
features['successorScore'] = self.getScore(successor)
return features
def getWeights(self, gameState, action):
return {'successorScore': 1.0}
def getHomeEntries(self, gameState):
walls = gameState.getWalls()
x = self.width // 2 - 1 if self.red else self.width // 2
entries = []
for y in range(1, self.height - 1):
if not walls[x][y]:
entries.append((x, y))
return entries or [self.start]
def minDistance(self, pos, targets):
if not pos or not targets:
return 0
return min(self.getMazeDistance(pos, target) for target in targets)
def activeEnemyGhostDistances(self, gameState, myPos):
distances = []
for opponent in self.getOpponents(gameState):
enemy = gameState.getAgentState(opponent)
enemyPos = enemy.getPosition()
if enemyPos is None:
continue
if not enemy.isPacman and enemy.scaredTimer <= 1:
distances.append(self.getMazeDistance(myPos, enemyPos))
return distances
def allVisibleGhostDistances(self, gameState, myPos):
active = []
scared = []
for opponent in self.getOpponents(gameState):
enemy = gameState.getAgentState(opponent)
enemyPos = enemy.getPosition()
if enemyPos is None or enemy.isPacman:
continue
dist = self.getMazeDistance(myPos, enemyPos)
if enemy.scaredTimer <= 1:
active.append(dist)
else:
scared.append(dist)
return active, scared
def deadEndDepth(self, pos):
if pos is None:
return 0
return self.deadEndDepths.get((int(pos[0]), int(pos[1])), 0)
class DeadEndOffensiveAgent(ReflexCaptureAgent):
def getFeatures(self, gameState, action):
features = util.Counter()
successor = self.getSuccessor(gameState, action)
myState = successor.getAgentState(self.index)
myPos = myState.getPosition()
foodList = self.getFood(successor).asList()
capsules = self.getCapsules(successor)
carrying = myState.numCarrying
activeGhostDistances, scaredGhostDistances = self.allVisibleGhostDistances(successor, myPos)
closestGhost = min(activeGhostDistances) if activeGhostDistances else None
closestScared = min(scaredGhostDistances) if scaredGhostDistances else None
features['successorScore'] = self.getScore(successor)
features['foodRemaining'] = len(foodList)
features['distanceToFood'] = self.adjustedFoodDistance(myPos, foodList, closestGhost, closestScared)
features['distanceHome'] = self.minDistance(myPos, self.homeEntries)
features['distanceToCapsule'] = self.minDistance(myPos, capsules)
features['deadEndDepth'] = self.deadEndDepth(myPos)
if action == Directions.STOP:
features['stop'] = 1
reverse = Directions.REVERSE[gameState.getAgentState(self.index).configuration.direction]
if action == reverse:
features['reverse'] = 1
if closestGhost is not None:
features['ghostDistance'] = closestGhost
if closestGhost <= 2:
features['immediateDanger'] = 1
elif closestGhost <= 5:
features['nearGhost'] = 1
if self.isEnteringRiskyDeadEnd(myPos, closestGhost, closestScared):
features['trapRisk'] = features['deadEndDepth']
if carrying >= 3 or len(foodList) <= 2:
features['shouldReturn'] = 1
if carrying > 0 and closestGhost is not None and closestGhost <= 6:
features['shouldReturn'] = 1
if closestGhost is not None and closestGhost <= 3 and features['deadEndDepth'] > 0:
features['shouldReturn'] = 1
if gameState.data.timeleft < features['distanceHome'] + 20:
features['shouldReturn'] = 1
return features
def adjustedFoodDistance(self, myPos, foodList, closestGhost, closestScared):
if not myPos or not foodList:
return 0
deadEndWeight = self.deadEndWeight(closestGhost, closestScared)
bestCost = None
for food in foodList:
cost = self.getMazeDistance(myPos, food) + self.deadEndDepth(food) * deadEndWeight
if bestCost is None or cost < bestCost:
bestCost = cost
return bestCost
def deadEndWeight(self, closestGhost, closestScared):
if closestGhost is None:
return 0.5
if closestGhost <= 2:
return 10.0
if closestGhost <= 4:
return 6.0
if closestGhost <= 6:
return 3.5
if closestScared is not None and closestScared <= 5:
return 0.2
return 1.0
def isEnteringRiskyDeadEnd(self, myPos, closestGhost, closestScared):
depth = self.deadEndDepth(myPos)
if depth <= 0:
return False
if closestGhost is None:
return depth >= 4
if closestScared is not None and closestGhost > 6:
return False
return closestGhost <= 6
def getWeights(self, gameState, action):
features = self.getFeatures(gameState, action)
weights = {
'successorScore': 200,
'foodRemaining': -100,
'distanceToFood': -3,
'distanceToCapsule': -2,
'ghostDistance': 2,
'immediateDanger': -1000,
'nearGhost': -180,
'deadEndDepth': -4,
'trapRisk': -45,
'stop': -100,
'reverse': -3,
'shouldReturn': 0,
'distanceHome': 0,
}
if features['shouldReturn']:
weights['distanceHome'] = -16
weights['distanceToFood'] = -1
weights['distanceToCapsule'] = -1
weights['deadEndDepth'] = -8
if features['nearGhost'] or features['immediateDanger']:
weights['distanceToCapsule'] = -8
weights['deadEndDepth'] = -12
return weights
class PatrolDefensiveAgent(ReflexCaptureAgent):
def registerInitialState(self, gameState):
ReflexCaptureAgent.registerInitialState(self, gameState)
self.patrolTarget = self.choosePatrolTarget(gameState)
self.lastEatenFood = None
def chooseAction(self, gameState):
self.updateLastEatenFood(gameState)
invaders = self.visibleInvaders(gameState)
if invaders:
myPos = gameState.getAgentPosition(self.index)
self.patrolTarget = min(
[a.getPosition() for a in invaders],
key=lambda p: self.getMazeDistance(myPos, p)
)
elif self.lastEatenFood is not None:
self.patrolTarget = self.lastEatenFood
elif self.patrolTarget is None:
self.patrolTarget = self.choosePatrolTarget(gameState)
return ReflexCaptureAgent.chooseAction(self, gameState)
def getFeatures(self, gameState, action):
features = util.Counter()
successor = self.getSuccessor(gameState, action)
myState = successor.getAgentState(self.index)
myPos = myState.getPosition()
invaders = self.visibleInvaders(successor)
features['onDefense'] = 1
if myState.isPacman:
features['onDefense'] = 0
features['numInvaders'] = len(invaders)
if invaders:
features['invaderDistance'] = min(
self.getMazeDistance(myPos, invader.getPosition()) for invader in invaders
)
else:
features['distanceToPatrol'] = self.getMazeDistance(myPos, self.patrolTarget)
if action == Directions.STOP:
features['stop'] = 1
reverse = Directions.REVERSE[gameState.getAgentState(self.index).configuration.direction]
if action == reverse:
features['reverse'] = 1
return features
def getWeights(self, gameState, action):
return {
'numInvaders': -1000,
'onDefense': 120,
'invaderDistance': -20,
'distanceToPatrol': -4,
'stop': -100,
'reverse': -2,
}
def visibleInvaders(self, gameState):
enemies = [gameState.getAgentState(i) for i in self.getOpponents(gameState)]
return [enemy for enemy in enemies if enemy.isPacman and enemy.getPosition() is not None]
def updateLastEatenFood(self, gameState):
previous = self.getPreviousObservation()
if previous is None:
return
previousFood = set(self.getFoodYouAreDefending(previous).asList())
currentFood = set(self.getFoodYouAreDefending(gameState).asList())
eaten = list(previousFood - currentFood)
if eaten:
myPos = gameState.getAgentPosition(self.index)
self.lastEatenFood = min(eaten, key=lambda p: self.getMazeDistance(myPos, p))
def choosePatrolTarget(self, gameState):
defendingFood = self.getFoodYouAreDefending(gameState).asList()
if not defendingFood:
return random.choice(self.homeEntries)
foodCenter = (
sum(x for x, y in defendingFood) / float(len(defendingFood)),
sum(y for x, y in defendingFood) / float(len(defendingFood))
)
return min(
self.homeEntries,
key=lambda p: abs(p[0] - foodCenter[0]) + abs(p[1] - foodCenter[1])
)