def explore_and_exploit(self,ant):
'''
Update weights and decide whether to explore or exploit here. Where all the magic happens.
YOUR CODE HERE
'''
actions = self.world.get_passable_directions(ant.location, AIM.keys())
random.shuffle(actions)
if len(actions)==0:
return 'halt'
# if we have a newborn baby ant, init its rewards and quality fcns
if 'prev_value' not in ant.__dict__:
ant.prev_value = 0
ant.previous_reward_events = RewardEvents()
ant.prev_features = self.features.extract(self.world, self.state, ant.location, actions[0])
return actions[0]
# step 1, update Q(s,a) based on going from last state, taking
# the action issued last round, and getting to current state
R = self.get_reward(ant.previous_reward_events)
# step size. it's good to make this inversely proportional to the
# number of features, so you don't bounce out of the bowl we're trying
# to descend via gradient descent
alpha = 0.00001
# totally greedy default value, future rewards count for nothing, do not want
discount = 0.00001
# should be max_a' Q(s',a'), where right now we are in state s' and the
# previous state was s. You can use
# self.value(self.state,ant.location,action) here
max_next_action = 'halt'
max_next_value = self.value(self.state, ant.location, actions[0])
for action in actions:
value = self.value(self.state, ant.location, action)
if value > max_next_value:
max_next_value = value
max_next_action = action
# should be argmax_a' Q(s',a')
# now that we have all the quantities needed, adjust the weights
self.update_weights(alpha,discount,R,max_next_value,ant.prev_value,ant.prev_features)
# step 2, explore or exploit? you should replace decide_to_explore with
# something sensible based on the number of games played so far, self.ngames
explore = 0.7 / self.ngames
decision = random.random()
if explore >= decision:
return actions[0]
else:
return max_next_action
def explore_and_exploit(self, ant):
'''
Update weights and decide whether to explore or exploit here. Where all the magic happens.
YOUR CODE HERE
'''
actions = self.world.get_passable_directions(ant.location, AIM.keys())
random.shuffle(actions)
if len(actions) == 0:
return 'halt'
# if we have a newborn baby ant, init its rewards and quality fcns
if 'prev_value' not in ant.__dict__:
ant.prev_value = 0
ant.previous_reward_events = RewardEvents()
ant.prev_features = self.features.extract(self.world, self.state,
ant.location, actions[0])
return actions[0]
# step 1, update Q(s,a) based on going from last state, taking
# the action issued last round, and getting to current state
R = self.get_reward(ant.previous_reward_events)
# step size. it's good to make this inversely proportional to the
# number of features, so you don't bounce out of the bowl we're trying
# to descend via gradient descent
alpha = 0.00001
# totally greedy default value, future rewards count for nothing, do not want
discount = 0.00001
# should be max_a' Q(s',a'), where right now we are in state s' and the
# previous state was s. You can use
# self.value(self.state,ant.location,action) here
max_next_action = 'halt'
max_next_value = self.value(self.state, ant.location, actions[0])
for action in actions:
value = self.value(self.state, ant.location, action)
if value > max_next_value:
max_next_value = value
max_next_action = action
# should be argmax_a' Q(s',a')
# now that we have all the quantities needed, adjust the weights
self.update_weights(alpha, discount, R, max_next_value, ant.prev_value,
ant.prev_features)
# step 2, explore or exploit? you should replace decide_to_explore with
# something sensible based on the number of games played so far, self.ngames
explore = 0.7 / self.ngames
decision = random.random()
if explore >= decision:
return actions[0]
else:
return max_next_action
def explore_and_exploit(self,ant):
'''
Update weights and decide whether to explore or exploit here. Where all the magic happens.
YOUR CODE HERE
'''
actions = self.world.get_passable_directions(ant.location, AIM.keys())
random.shuffle(actions)
if len(actions)==0:
return 'halt'
# if we have a newborn baby ant, init its rewards and quality fcns
if 'prev_value' not in ant.__dict__:
ant.prev_value = 0
ant.previous_reward_events = RewardEvents()
ant.prev_features = self.features.extract(self.world, self.state, ant.location, actions[0])
return actions[0]
# step 1, update Q(s,a) based on going from last state, taking
# the action issued last round, and getting to current state
R = self.get_reward(ant.previous_reward_events)
# step size. it's good to make this inversely proportional to the
# number of features, so you don't bounce out of the bowl we're trying
# to descend via gradient descent
alpha = 0.01 / (len(self.weights))
# totally greedy default value, future rewards count for nothing, do not want
discount = 1.0
# should be max_a' Q(s',a'), where right now we are in state s' and the
# previous state was s. You can use
# self.value(self.state,ant.location,action) here
# SO WHY NOT JUST PUT THAT IN THE CODE INSTEAD OF LEAVING A CRYPTIC COMMENT!?
(max_next_value, max_next_action) = max_by(actions, lambda x: self.value(self.state,ant.location,x))
# now that we have all the quantities needed, adjust the weights
self.update_weights(alpha,discount,R,max_next_value,ant.prev_value,ant.prev_features)
# step 2, explore or exploit? you should replace decide_to_explore with
# something sensible based on the number of games played so far, self.ngames
decide_to_explore = None
if self.ngames < explore_start:
decide_to_explore = True
elif self.ngames < explore_stop:
p = 1.0 * (explore_stop - self.ngames) / (explore_stop - explore_start)
decide_to_explore = random.random() < p
else:
decide_to_explore = False
if decide_to_explore:
return actions[0]
else:
return max_next_action
def get_direction(self, ant):
'''Finds a direction for this ant to move in according to the food, enemy, exploration routine.'''
# Get the list of directions towards food, enemy, and random
rand_dirs = AIM.keys()
random.shuffle(rand_dirs)
dirs = (ant.toward(ant.closest_food()) + ant.toward(ant.closest_enemy()) + rand_dirs)
# Get the first passable direction from that long list.
d = ant.get_passable_direction(dirs)
return d
def get_direction(self, ant):
'''Finds a direction for this ant to move in according to the food, enemy, exploration routine.'''
# Get the list of directions towards food, enemy, and random
rand_dirs = AIM.keys()
random.shuffle(rand_dirs)
dirs = (ant.toward(ant.closest_food()) + ant.toward(ant.closest_enemy()) + rand_dirs)
# Get the first passable direction from that long list.
d = ant.get_passable_direction(dirs)
return d
def get_successors(self,loc):
'''
Returns a list of valid next reachable locations from the input LOC.
All derived classes should use this function, otherwise testing your implementation might fail.
'''
alldirs = AIM.keys()
s = []
for d in alldirs:
l = self.world.next_position(loc, d)
if self.world.passable(l):
s.append(l)
return s
def get_direction(self, ant):
"""Evaluates each of the currently passable directions and picks the one with maximum value."""
# get the passable directions, in random order to break ties
rand_dirs = self.world.get_passable_directions(ant.location, AIM.keys())
random.shuffle(rand_dirs)
# evaluate the value function for each possible direction
value = [0 for i in range(0, len(rand_dirs))]
max_value = float("-inf")
max_dir = None
for i in range(0, len(rand_dirs)):
value[i] = self.value(self.state, ant.location, rand_dirs[i])
if value[i] > max_value:
max_value = value[i]
max_dir = rand_dirs[i]
# take direction with maximum value
# Get the first passable direction from that long list.
self.world.L.info("Chose: %s, value: %.2f" % (max_dir, max_value))
return max_dir
def get_direction(self, state, ant):
'''Returns the ant's least-visited adjacent location, prioritizing by
food direction when multiple adjacent locations are equally explored.'''
# Of the 4 possible squares to move to, determine which don't currently
# contain an ant and are the least-visited.
min_visits = float('Inf')
min_visits_directions = []
for direction in AIM.keys():
test_position = ant.world.next_position(ant.location, direction)
# Ignore water.
if not ant.world.passable(test_position):
continue
# Don't move to a currently occupied location;
# this helps somewhat mitigate collisions.
if ant.world.ant_lookup[test_position] != -1:
continue
# Check to see how frequently this candidate location has been visited
# in the past.
num_visits = state[test_position] if state.has_key(
test_position) else 1
if num_visits < min_visits:
min_visits = num_visits
min_visits_directions = [direction]
elif num_visits == min_visits:
min_visits_directions.append(direction)
if not min_visits_directions:
# Will only reach here if ant is boxed in by water on all sides.
return None
elif len(min_visits_directions) > 1:
# Try to break ties by considering food direction.
food_directions = ant.toward(ant.closest_food())
for fd in food_directions:
if fd in min_visits_directions:
return fd
return min_visits_directions[0]
def get_direction(self, state, ant):
'''Returns the ant's least-visited adjacent location, prioritizing by
food direction when multiple adjacent locations are equally explored.'''
# Of the 4 possible squares to move to, determine which don't currently
# contain an ant and are the least-visited.
min_visits = float('Inf')
min_visits_directions = []
for direction in AIM.keys():
test_position = ant.world.next_position(ant.location, direction)
# Ignore water.
if not ant.world.passable(test_position):
continue
# Don't move to a currently occupied location;
# this helps somewhat mitigate collisions.
if ant.world.ant_lookup[test_position] != -1:
continue
# Check to see how frequently this candidate location has been visited
# in the past.
num_visits = state[test_position] if state.has_key(test_position) else 1
if num_visits < min_visits:
min_visits = num_visits
min_visits_directions = [direction]
elif num_visits == min_visits:
min_visits_directions.append(direction)
if not min_visits_directions:
# Will only reach here if ant is boxed in by water on all sides.
return None
elif len(min_visits_directions) > 1:
# Try to break ties by considering food direction.
food_directions = ant.toward(ant.closest_food())
for fd in food_directions:
if fd in min_visits_directions:
return fd
return min_visits_directions[0]