def test_prefixsum_idx():
"""
test Segment Tree data structure
"""
tree = SumSegmentTree(4)
tree[2] = 1.0
tree[3] = 3.0
assert tree.find_prefixsum_idx(0.0) == 2
assert tree.find_prefixsum_idx(0.5) == 2
assert tree.find_prefixsum_idx(0.99) == 2
assert tree.find_prefixsum_idx(1.01) == 3
assert tree.find_prefixsum_idx(3.00) == 3
assert tree.find_prefixsum_idx(4.00) == 3
assert np.all(tree.find_prefixsum_idx([0.0, 0.5, 0.99, 1.01, 3.00, 4.00]) == [2, 2, 2, 3, 3, 3])
tree = SumSegmentTree(4)
tree[np.array([2, 3])] = [1.0, 3.0]
assert tree.find_prefixsum_idx(0.0) == 2
assert tree.find_prefixsum_idx(0.5) == 2
assert tree.find_prefixsum_idx(0.99) == 2
assert tree.find_prefixsum_idx(1.01) == 3
assert tree.find_prefixsum_idx(3.00) == 3
assert tree.find_prefixsum_idx(4.00) == 3
assert np.all(tree.find_prefixsum_idx([0.0, 0.5, 0.99, 1.01, 3.00, 4.00]) == [2, 2, 2, 3, 3, 3])
def test_prefixsum_idx():
"""
test Segment Tree data structure
"""
tree = SumSegmentTree(4)
tree[2] = 1.0
tree[3] = 3.0
assert tree.find_prefixsum_idx(0.0) == 2
assert tree.find_prefixsum_idx(0.5) == 2
assert tree.find_prefixsum_idx(0.99) == 2
assert tree.find_prefixsum_idx(1.01) == 3
assert tree.find_prefixsum_idx(3.00) == 3
assert tree.find_prefixsum_idx(4.00) == 3
def test_prefixsum_idx2():
"""
test Segment Tree data structure
"""
tree = SumSegmentTree(4)
tree[0] = 0.5
tree[1] = 1.0
tree[2] = 1.0
tree[3] = 3.0
assert tree.find_prefixsum_idx(0.00) == 0
assert tree.find_prefixsum_idx(0.55) == 1
assert tree.find_prefixsum_idx(0.99) == 1
assert tree.find_prefixsum_idx(1.51) == 2
assert tree.find_prefixsum_idx(3.00) == 3
assert tree.find_prefixsum_idx(5.50) == 3
class PrioritizedReplayBuffer(ReplayBuffer):
def __init__(self, size, alpha):
"""
Create Prioritized Replay buffer.
See Also ReplayBuffer.__init__
:param size: (int) Max number of transitions to store in the buffer. When the buffer overflows the old memories
are dropped.
:param alpha: (float) how much prioritization is used (0 - no prioritization, 1 - full prioritization)
"""
super(PrioritizedReplayBuffer, self).__init__(size)
assert alpha >= 0
self._alpha = alpha
it_capacity = 1
while it_capacity < size:
it_capacity *= 2
self._it_sum = SumSegmentTree(it_capacity)
self._it_min = MinSegmentTree(it_capacity)
self._max_priority = 1.0
def add(self, obs_t, action, reward, obs_tp1, done):
"""
add a new transition to the buffer
:param obs_t: (Any) the last observation
:param action: ([float]) the action
:param reward: (float) the reward of the transition
:param obs_tp1: (Any) the current observation
:param done: (bool) is the episode done
"""
idx = self._next_idx
super().add(obs_t, action, reward, obs_tp1, done)
self._it_sum[idx] = self._max_priority**self._alpha
self._it_min[idx] = self._max_priority**self._alpha
def _sample_proportional(self, batch_size):
res = []
for _ in range(batch_size):
# TODO(szymon): should we ensure no repeats?
mass = random.random() * self._it_sum.sum(0,
len(self._storage) - 1)
idx = self._it_sum.find_prefixsum_idx(mass)
res.append(idx)
return res
def sample(self, batch_size, beta=0):
"""
Sample a batch of experiences.
compared to ReplayBuffer.sample
it also returns importance weights and idxes
of sampled experiences.
:param batch_size: (int) How many transitions to sample.
:param beta: (float) To what degree to use importance weights (0 - no corrections, 1 - full correction)
:return:
- obs_batch: (np.ndarray) batch of observations
- act_batch: (numpy float) batch of actions executed given obs_batch
- rew_batch: (numpy float) rewards received as results of executing act_batch
- next_obs_batch: (np.ndarray) next set of observations seen after executing act_batch
- done_mask: (numpy bool) done_mask[i] = 1 if executing act_batch[i] resulted in the end of an episode
and 0 otherwise.
- weights: (numpy float) Array of shape (batch_size,) and dtype np.float32 denoting importance weight of
each sampled transition
- idxes: (numpy int) Array of shape (batch_size,) and dtype np.int32 idexes in buffer of sampled experiences
"""
assert beta > 0
idxes = self._sample_proportional(batch_size)
weights = []
p_min = self._it_min.min() / self._it_sum.sum()
max_weight = (p_min * len(self._storage))**(-beta)
for idx in idxes:
p_sample = self._it_sum[idx] / self._it_sum.sum()
weight = (p_sample * len(self._storage))**(-beta)
weights.append(weight / max_weight)
weights = np.array(weights)
encoded_sample = self._encode_sample(idxes)
return tuple(list(encoded_sample) + [weights, idxes])
def update_priorities(self, idxes, priorities):
"""
Update priorities of sampled transitions.
sets priority of transition at index idxes[i] in buffer
to priorities[i].
:param idxes: ([int]) List of idxes of sampled transitions
:param priorities: ([float]) List of updated priorities corresponding to transitions at the sampled idxes
denoted by variable `idxes`.
"""
assert len(idxes) == len(priorities)
for idx, priority in zip(idxes, priorities):
assert priority > 0
assert 0 <= idx < len(self._storage)
self._it_sum[idx] = priority**self._alpha
self._it_min[idx] = priority**self._alpha
self._max_priority = max(self._max_priority, priority)
class EpisodicMemory(object):
def __init__(self,
buffer_size,
state_dim,
action_shape,
obs_space,
q_func,
repr_func,
obs_ph,
action_ph,
sess,
gamma=0.99,
alpha=0.6,
max_step=1000):
buffer_size = int(buffer_size)
self.state_dim = state_dim
self.capacity = buffer_size
self.curr_capacity = 0
self.pointer = 0
self.obs_space = obs_space
self.action_shape = action_shape
self.max_step = max_step
self.query_buffer = np.zeros((buffer_size, state_dim))
self._q_values = -np.inf * np.ones(buffer_size + 1)
self.returns = -np.inf * np.ones(buffer_size + 1)
self.replay_buffer = np.empty((buffer_size, ) + obs_space.shape,
np.float32)
self.action_buffer = np.empty((buffer_size, ) + action_shape,
np.float32)
self.reward_buffer = np.empty((buffer_size, ), np.float32)
self.steps = np.empty((buffer_size, ), np.int)
self.done_buffer = np.empty((buffer_size, ), np.bool)
self.truly_done_buffer = np.empty((buffer_size, ), np.bool)
self.next_id = -1 * np.ones(buffer_size)
self.prev_id = [[] for _ in range(buffer_size)]
self.ddpg_q_values = -np.inf * np.ones(buffer_size)
self.contra_count = np.ones((buffer_size, ))
self.lru = np.zeros(buffer_size)
self.time = 0
self.gamma = gamma
# self.hashes = dict()
self.reward_mean = None
self.min_return = 0
self.end_points = []
assert alpha > 0
self._alpha = alpha
self.beta_set = [-1]
self.beta_coef = [1.]
it_capacity = 1
while it_capacity < buffer_size:
it_capacity *= 2
self._it_sum = SumSegmentTree(it_capacity)
self._it_min = MinSegmentTree(it_capacity)
self._max_priority = 1.0
self.q_func = q_func
self.repr_func = repr_func
self.obs_ph = obs_ph
self.action_ph = action_ph
self.sess = sess
def clean(self):
buffer_size, state_dim, obs_space, action_shape = self.capacity, self.state_dim, self.obs_space, self.action_shape
self.curr_capacity = 0
self.pointer = 0
self.query_buffer = np.zeros((buffer_size, state_dim))
self._q_values = -np.inf * np.ones(buffer_size + 1)
self.returns = -np.inf * np.ones(buffer_size + 1)
self.replay_buffer = np.empty((buffer_size, ) + obs_space.shape,
np.float32)
self.action_buffer = np.empty((buffer_size, ) + action_shape,
np.float32)
self.reward_buffer = np.empty((buffer_size, ), np.float32)
self.steps = np.empty((buffer_size, ), np.int)
self.done_buffer = np.empty((buffer_size, ), np.bool)
self.truly_done_buffer = np.empty((buffer_size, ), np.bool)
self.next_id = -1 * np.ones(buffer_size)
self.prev_id = [[] for _ in range(buffer_size)]
self.ddpg_q_values = -np.inf * np.ones(buffer_size)
self.contra_count = np.ones((buffer_size, ))
self.lru = np.zeros(buffer_size)
self.time = 0
it_capacity = 1
while it_capacity < buffer_size:
it_capacity *= 2
self._it_sum = SumSegmentTree(it_capacity)
self._it_min = MinSegmentTree(it_capacity)
self._max_priority = 1.0
self.end_points = []
@property
def q_values(self):
return self._q_values
def squeeze(self, obses):
return np.array([(obs - self.obs_space.low) /
(self.obs_space.high - self.obs_space.low)
for obs in obses])
def unsqueeze(self, obses):
return np.array([
obs * (self.obs_space.high - self.obs_space.low) +
self.obs_space.low for obs in obses
])
def save(self, filedir):
save_dict = {
"query_buffer": self.query_buffer,
"returns": self.returns,
"replay_buffer": self.replay_buffer,
"reward_buffer": self.reward_buffer,
"truly_done_buffer": self.truly_done_buffer,
"next_id": self.next_id,
"prev_id": self.prev_id,
"gamma": self.gamma,
"_q_values": self._q_values,
"done_buffer": self.done_buffer,
"curr_capacity": self.curr_capacity,
"capacity": self.capacity
}
with open(os.path.join(filedir, "episodic_memory.pkl"),
"wb") as memory_file:
pkl.dump(save_dict, memory_file)
def add(self, obs, action, state, sampled_return, next_id=-1):
index = self.pointer
self.pointer = (self.pointer + 1) % self.capacity
if self.curr_capacity >= self.capacity:
# Clean up old entry
if index in self.end_points:
self.end_points.remove(index)
self.prev_id[index] = []
self.next_id[index] = -1
self.q_values[index] = -np.inf
else:
self.curr_capacity = min(self.capacity, self.curr_capacity + 1)
# Store new entry
self.replay_buffer[index] = obs
self.action_buffer[index] = action
if state is not None:
self.query_buffer[index] = state
self.q_values[index] = sampled_return
self.returns[index] = sampled_return
self.lru[index] = self.time
self._it_sum[index] = self._max_priority**self._alpha
self._it_min[index] = self._max_priority**self._alpha
if next_id >= 0:
self.next_id[index] = next_id
if index not in self.prev_id[next_id]:
self.prev_id[next_id].append(index)
self.time += 0.01
return index
def update_priority(self, idxes, priorities):
# priorities = 1 / np.sqrt(self.contra_count[:self.curr_capacity])
# priorities = priorities / np.max(priorities)
assert len(idxes) == len(priorities)
for idx, priority in zip(idxes, priorities):
priority = max(priority, 1e-6)
# assert priority > 0
assert 0 <= idx < self.capacity
self._it_sum[idx] = priority**self._alpha
self._it_min[idx] = priority**self._alpha
self._max_priority = max(self._max_priority, priority)
def sample_neg_keys(self, avoids, batch_size):
# sample negative keys
assert batch_size + len(
avoids
) <= self.capacity, "can't sample that much neg samples from episodic memory!"
places = []
while len(places) < batch_size:
ind = np.random.randint(0, self.curr_capacity)
if ind not in places:
places.append(ind)
return places
def compute_approximate_return(self, obses, actions=None):
return np.min(np.array(
self.sess.run(self.q_func, feed_dict={self.obs_ph: obses})),
axis=0)
def compute_statistics(self, batch_size=1024):
estimated_qs = []
for i in range(math.ceil(self.curr_capacity / batch_size)):
start = i * batch_size
end = min((i + 1) * batch_size, self.curr_capacity)
obses = self.replay_buffer[start:end]
actions = None
estimated_qs.append(
self.compute_approximate_return(obses, actions).reshape(-1))
estimated_qs = np.concatenate(estimated_qs)
diff = estimated_qs - self.q_values[:self.curr_capacity]
return np.min(diff), np.mean(diff), np.max(diff)
def retrieve_trajectories(self):
trajs = []
for e in self.end_points:
traj = []
prev = e
while prev is not None:
traj.append(prev)
try:
prev = self.prev_id[prev][0]
# print(e,prev)
except IndexError:
prev = None
# print(np.array(traj))
trajs.append(np.array(traj))
return trajs
def update_memory(self, q_base=0, use_knn=False, beta=-1):
trajs = self.retrieve_trajectories()
for traj in trajs:
# print(np.array(traj))
approximate_qs = self.compute_approximate_return(
self.replay_buffer[traj], self.action_buffer[traj])
approximate_qs = approximate_qs.reshape(-1)
approximate_qs = np.insert(approximate_qs, 0, 0)
self.q_values[traj] = 0
Rtn = -1e10 if beta < 0 else 0
for i, s in enumerate(traj):
approximate_q = self.reward_buffer[s] + \
self.gamma * (1 - self.truly_done_buffer[s]) * (approximate_qs[i] - q_base)
Rtn = self.reward_buffer[s] + self.gamma * (
1 - self.truly_done_buffer[s]) * Rtn
if beta < 0:
Rtn = max(Rtn, approximate_q)
else:
Rtn = beta * Rtn + (1 - beta) * approximate_q
self.q_values[s] = Rtn
def update_sequence_with_qs(self, sequence):
# print(sequence)
next_id = -1
Rtd = 0
for obs, a, z, q_t, r, truly_done, done in reversed(sequence):
# print(np.mean(z))
if truly_done:
Rtd = r
else:
Rtd = self.gamma * Rtd + r
current_id = self.add(obs, a, z, Rtd, next_id)
if done:
self.end_points.append(current_id)
self.replay_buffer[current_id] = obs
self.reward_buffer[current_id] = r
self.truly_done_buffer[current_id] = truly_done
self.done_buffer[current_id] = done
next_id = int(current_id)
# self.update_priority()
return
def sample_negative(self, batch_size, batch_idxs, batch_idxs_next,
batch_idx_pre):
neg_batch_idxs = []
i = 0
while i < batch_size:
neg_idx = np.random.randint(0, self.curr_capacity - 2)
if neg_idx != batch_idxs[i] and neg_idx != batch_idxs_next[
i] and neg_idx not in batch_idx_pre[i]:
neg_batch_idxs.append(neg_idx)
i += 1
neg_batch_idxs = np.array(neg_batch_idxs)
return neg_batch_idxs, self.replay_buffer[neg_batch_idxs]
@staticmethod
def switch_first_half(obs0, obs1, batch_size):
tmp = copy.copy(obs0[:batch_size // 2, ...])
obs0[:batch_size // 2, ...] = obs1[:batch_size // 2, ...]
obs1[:batch_size // 2, ...] = tmp
return obs0, obs1
def sample(self, batch_size, mix=False, priority=False):
# Draw such that we always have a proceeding element
if self.curr_capacity < batch_size + len(self.end_points):
return None
# if priority:
# self.update_priority()
batch_idxs = []
batch_idxs_next = []
count = 0
while len(batch_idxs) < batch_size:
if priority:
mass = random.random() * self._it_sum.sum(
0, self.curr_capacity)
rnd_idx = self._it_sum.find_prefixsum_idx(mass)
else:
rnd_idx = np.random.randint(0, self.curr_capacity)
count += 1
assert count < 1e8
if self.next_id[rnd_idx] == -1:
continue
# be careful !!!!!! I use random id because in our implementation obs1 is never used
# if len(self.prev_id[rnd_idx]) > 0:
# batch_idxs_next.append(self.prev_id[rnd_idx][0])
# else:
# batch_idxs_next.append(0)
else:
batch_idxs_next.append(self.next_id[rnd_idx])
batch_idxs.append(rnd_idx)
batch_idxs = np.array(batch_idxs).astype(np.int)
batch_idxs_next = np.array(batch_idxs_next).astype(np.int)
# batch_idx_pre = [self.prev_id[id] for id in batch_idxs]
obs0_batch = self.replay_buffer[batch_idxs]
obs1_batch = self.replay_buffer[batch_idxs_next]
# batch_idxs_neg, obs2_batch = self.sample_negative(batch_size, batch_idxs, batch_idxs_next, batch_idx_pre)
action_batch = self.action_buffer[batch_idxs]
action1_batch = self.action_buffer[batch_idxs_next]
# action2_batch = self.action_buffer[batch_idxs_neg]
reward_batch = self.reward_buffer[batch_idxs]
terminal1_batch = self.done_buffer[batch_idxs]
q_batch = self.q_values[batch_idxs]
return_batch = self.returns[batch_idxs]
if mix:
obs0_batch, obs1_batch = self.switch_first_half(
obs0_batch, obs1_batch, batch_size)
if priority:
self.contra_count[batch_idxs] += 1
self.contra_count[batch_idxs_next] += 1
result = {
'index0':
array_min2d(batch_idxs),
'index1':
array_min2d(batch_idxs_next),
# 'index2': array_min2d(batch_idxs_neg),
'obs0':
array_min2d(obs0_batch),
'obs1':
array_min2d(obs1_batch),
# 'obs2': array_min2d(obs2_batch),
'rewards':
array_min2d(reward_batch),
'actions':
array_min2d(action_batch),
'actions1':
array_min2d(action1_batch),
# 'actions2': array_min2d(action2_batch),
'count':
array_min2d(self.contra_count[batch_idxs] +
self.contra_count[batch_idxs_next]),
'terminals1':
array_min2d(terminal1_batch),
'return':
array_min2d(q_batch),
'true_return':
array_min2d(return_batch),
}
return result
def plot(self):
X = self.replay_buffer[:self.curr_capacity]
model = TSNE()
low_dim_data = model.fit_transform(X)
plt.scatter(low_dim_data[:, 0], low_dim_data[:, 1])
plt.show()
class TwoWayPrioritizedReplayBuffer(ReplayBuffer):
def __init__(self, size, alpha):
super(PrioritizedReplayBuffer, self).__init__(size)
assert alpha >= 0
self._alpha = alpha
it_capacity = 1
while it_capacity < size:
it_capacity *= 2
self._it_sum = SumSegmentTree(it_capacity)
self._it_min = MinSegmentTree(it_capacity)
self._max_priority = 1.0
def add(self, obs_t, action, reward, obs_tp1, done):
idx = self._next_idx
super().add(obs_t, action, reward, obs_tp1, done)
self._it_sum[idx] = self._max_priority**self._alpha
self._it_min[idx] = self._max_priority**self._alpha
def extend(self, obs_t, action, reward, obs_tp1, done):
idx = self._next_idx
super().extend(obs_t, action, reward, obs_tp1, done)
while idx != self._next_idx:
self._it_sum[idx] = self._max_priority**self._alpha
self._it_min[idx] = self._max_priority**self._alpha
idx = (idx + 1) % self._maxsize
def _sample_proportional(self, batch_size):
mass = []
total = self._it_sum.sum(0, len(self._storage) - 1)
# TODO(szymon): should we ensure no repeats?
mass = np.random.random(size=batch_size) * total
idx = self._it_sum.find_prefixsum_idx(mass)
return idx
def sample(self,
batch_size: int,
beta: float = 0,
env: Optional[VecNormalize] = None):
assert beta > 0
idxes = self._sample_proportional(batch_size)
weights = []
p_min = self._it_min.min() / self._it_sum.sum()
max_weight = (p_min * len(self._storage))**(-beta)
p_sample = self._it_sum[idxes] / self._it_sum.sum()
weights = (p_sample * len(self._storage))**(-beta) / max_weight
encoded_sample = self._encode_sample(idxes, env=env)
return tuple(list(encoded_sample) + [weights, idxes])
def _sample_invproportional(self, batch_size):
mass = []
total = self._it_sum.sum(len(self._storage) - 1, 0)
# TODO(szymon): should we ensure no repeats?
mass = np.random.random(size=batch_size) * total
idx = self._it_sum.find_prefixsum_idx(mass)
return idx
def invsample(self,
batch_size: int,
beta: float = 0,
env: Optional[VecNormalize] = None):
assert beta > 0
idxes = self._sample_invproportional(batch_size)
encoded_sample = self._encode_sample(idxes, env=env)
return list(encoded_sample)
def update_priorities(self, idxes, priorities):
assert len(idxes) == len(priorities)
assert np.min(priorities) > 0
assert np.min(idxes) >= 0
assert np.max(idxes) < len(self.storage)
self._it_sum[idxes] = priorities**self._alpha
self._it_min[idxes] = priorities**self._alpha
self._max_priority = max(self._max_priority, np.max(priorities))
class PrioritizedReplayBuffer(ReplayBuffer):
def __init__(self, size, alpha):
"""
Create Prioritized Replay buffer.
See Also ReplayBuffer.__init__
:param size: (int) Max number of transitions to store in the buffer. When the buffer overflows the old memories
are dropped.
:param alpha: (float) how much prioritization is used (0 - no prioritization, 1 - full prioritization)
"""
super(PrioritizedReplayBuffer, self).__init__(size)
assert alpha >= 0
self._alpha = alpha
it_capacity = 1
while it_capacity < size:
it_capacity *= 2
self._it_sum = SumSegmentTree(it_capacity)
self._it_min = MinSegmentTree(it_capacity)
self._max_priority = 1.0
def add(self, obs_t, action, reward, obs_tp1, done):
"""
add a new transition to the buffer
:param obs_t: (Any) the last observation
:param action: ([float]) the action
:param reward: (float) the reward of the transition
:param obs_tp1: (Any) the current observation
:param done: (bool) is the episode done
"""
idx = self._next_idx
super().add(obs_t, action, reward, obs_tp1, done)
self._it_sum[idx] = self._max_priority**self._alpha
self._it_min[idx] = self._max_priority**self._alpha
def extend(self, obs_t, action, reward, obs_tp1, done):
"""
add a new batch of transitions to the buffer
:param obs_t: (Union[Tuple[Union[np.ndarray, int]], np.ndarray]) the last batch of observations
:param action: (Union[Tuple[Union[np.ndarray, int]]], np.ndarray]) the batch of actions
:param reward: (Union[Tuple[float], np.ndarray]) the batch of the rewards of the transition
:param obs_tp1: (Union[Tuple[Union[np.ndarray, int]], np.ndarray]) the current batch of observations
:param done: (Union[Tuple[bool], np.ndarray]) terminal status of the batch
Note: uses the same names as .add to keep compatibility with named argument passing
but expects iterables and arrays with more than 1 dimensions
"""
idx = self._next_idx
super().extend(obs_t, action, reward, obs_tp1, done)
while idx != self._next_idx:
self._it_sum[idx] = self._max_priority**self._alpha
self._it_min[idx] = self._max_priority**self._alpha
idx = (idx + 1) % self._maxsize
def _sample_proportional(self, batch_size):
mass = []
total = self._it_sum.sum(0, len(self._storage) - 1)
# TODO(szymon): should we ensure no repeats?
mass = np.random.random(size=batch_size) * total
idx = self._it_sum.find_prefixsum_idx(mass)
return idx
def sample(self,
batch_size: int,
beta: float = 0,
env: Optional[VecNormalize] = None):
"""
Sample a batch of experiences.
compared to ReplayBuffer.sample
it also returns importance weights and idxes
of sampled experiences.
:param batch_size: (int) How many transitions to sample.
:param beta: (float) To what degree to use importance weights (0 - no corrections, 1 - full correction)
:param env: (Optional[VecNormalize]) associated gym VecEnv
to normalize the observations/rewards when sampling
:return:
- obs_batch: (np.ndarray) batch of observations
- act_batch: (numpy float) batch of actions executed given obs_batch
- rew_batch: (numpy float) rewards received as results of executing act_batch
- next_obs_batch: (np.ndarray) next set of observations seen after executing act_batch
- done_mask: (numpy bool) done_mask[i] = 1 if executing act_batch[i] resulted in the end of an episode
and 0 otherwise.
- weights: (numpy float) Array of shape (batch_size,) and dtype np.float32 denoting importance weight of
each sampled transition
- idxes: (numpy int) Array of shape (batch_size,) and dtype np.int32 idexes in buffer of sampled experiences
"""
assert beta > 0
idxes = self._sample_proportional(batch_size)
weights = []
p_min = self._it_min.min() / self._it_sum.sum()
max_weight = (p_min * len(self._storage))**(-beta)
p_sample = self._it_sum[idxes] / self._it_sum.sum()
weights = (p_sample * len(self._storage))**(-beta) / max_weight
encoded_sample = self._encode_sample(idxes, env=env)
return tuple(list(encoded_sample) + [weights, idxes])
def update_priorities(self, idxes, priorities):
"""
Update priorities of sampled transitions.
sets priority of transition at index idxes[i] in buffer
to priorities[i].
:param idxes: ([int]) List of idxes of sampled transitions
:param priorities: ([float]) List of updated priorities corresponding to transitions at the sampled idxes
denoted by variable `idxes`.
"""
assert len(idxes) == len(priorities)
assert np.min(priorities) > 0
assert np.min(idxes) >= 0
assert np.max(idxes) < len(self.storage)
self._it_sum[idxes] = priorities**self._alpha
self._it_min[idxes] = priorities**self._alpha
self._max_priority = max(self._max_priority, np.max(priorities))
class PrioritizedReplayBuffer(ReplayBuffer):
def __init__(self, size, alpha):
"""Create Prioritized Replay buffer.
Parameters
----------
size: int
Max number of transitions to store in the buffer. When the buffer
overflows the old memories are dropped.
alpha: float
how much prioritization is used
(0 - no prioritization, 1 - full prioritization)
See Also
--------
ReplayBuffer.__init__
"""
super(PrioritizedReplayBuffer, self).__init__(size)
assert alpha > 0
self._alpha = alpha
it_capacity = 1
while it_capacity < size:
it_capacity *= 2
self._it_sum = SumSegmentTree(it_capacity)
self._it_min = MinSegmentTree(it_capacity)
self._max_priority = 1.0
def add(self, *args, **kwargs):
"""See ReplayBuffer.store_effect"""
idx = self._next_idx
super().add(*args, **kwargs)
self._it_sum[idx] = self._max_priority**self._alpha
self._it_min[idx] = self._max_priority**self._alpha
def _sample_proportional(self, batch_size):
res = []
for _ in range(batch_size):
# TODO(szymon): should we ensure no repeats?
mass = random.random() * self._it_sum.sum(0,
len(self._storage) - 1)
idx = self._it_sum.find_prefixsum_idx(mass)
res.append(idx)
return res
def sample(self, batch_size, beta):
"""Sample a batch of experiences.
compared to ReplayBuffer.sample
it also returns importance weights and idxes
of sampled experiences.
Parameters
----------
batch_size: int
How many transitions to sample.
beta: float
To what degree to use importance weights
(0 - no corrections, 1 - full correction)
Returns
-------
obs_batch: np.array
batch of observations
act_batch: np.array
batch of actions executed given obs_batch
R_batch: np.array
returns received as results of executing act_batch
weights: np.array
Array of shape (batch_size,) and dtype np.float32
denoting importance weight of each sampled transition
idxes: np.array
Array of shape (batch_size,) and dtype np.int32
idexes in buffer of sampled experiences
"""
idxes = self._sample_proportional(batch_size)
if beta > 0:
weights = []
p_min = self._it_min.min() / self._it_sum.sum()
max_weight = (p_min * len(self._storage))**(-beta)
for idx in idxes:
p_sample = self._it_sum[idx] / self._it_sum.sum()
weight = (p_sample * len(self._storage))**(-beta)
weights.append(weight / max_weight)
weights = np.array(weights)
else:
weights = np.ones_like(idxes, dtype=np.float32)
encoded_sample = self._encode_sample(idxes)
return tuple(list(encoded_sample) + [weights, idxes])
def update_priorities(self, idxes, priorities):
"""Update priorities of sampled transitions.
sets priority of transition at index idxes[i] in buffer
to priorities[i].
Parameters
----------
idxes: [int]
List of idxes of sampled transitions
priorities: [float]
List of updated priorities corresponding to
transitions at the sampled idxes denoted by
variable `idxes`.
"""
assert len(idxes) == len(priorities)
for idx, priority in zip(idxes, priorities):
priority = max(priority, 1e-6)
assert priority > 0
assert 0 <= idx < len(self._storage)
self._it_sum[idx] = priority**self._alpha
self._it_min[idx] = priority**self._alpha
self._max_priority = max(self._max_priority, priority)
class PrioritizedMemory(Memory):
def __init__(self,
capacity,
alpha,
transition_small_epsilon=1e-6,
demo_epsilon=0.2):
super(PrioritizedMemory, self).__init__(capacity)
assert alpha > 0
self._alpha = alpha
self._transition_small_epsilon = transition_small_epsilon
self._demo_epsilon = demo_epsilon
it_capacity = 1
while it_capacity < self.capacity:
it_capacity *= 2 # Size must be power of 2
self._it_sum = SumSegmentTree(it_capacity)
self._it_min = MinSegmentTree(it_capacity)
self._max_priority = 100.0
self.help = []
def append(self, obs0, obs1, f_s0, f_s1, action, reward, terminal1):
idx = self._next_idx
if not super(PrioritizedMemory, self).append_(obs0=obs0,
obs1=obs1,
f_s0=f_s0,
f_s1=f_s1,
actions=action,
rewards=reward,
terminal1=terminal1):
return
# 新加入的'transition'设置为最大优先级, 确保每一个'transition'都至少被采样一次
self._it_sum[idx] = self._max_priority
self._it_min[idx] = self._max_priority
def append_demo(self, obs0, obs1, f_s0, f_s1, action, reward, terminal1):
idx = self._next_idx
if not super(PrioritizedMemory, self).append_(obs0=obs0,
obs1=obs1,
f_s0=f_s0,
f_s1=f_s1,
actions=action,
rewards=reward,
terminal1=terminal1,
count=False):
return
self._it_sum[idx] = self._max_priority
self._it_min[idx] = self._max_priority
self.num_demonstrations += 1
def _sample_proportional(self, batch_size, pretrain):
res = []
if pretrain:
res = np.random.random_integers(low=0,
high=self.nb_entries - 1,
size=batch_size)
return res
for _ in range(batch_size):
while True:
mass = np.random.uniform(
0, self._it_sum.sum(0,
len(self.storage) - 1))
idx = self._it_sum.find_prefixsum_idx(mass)
if idx not in res:
res.append(idx)
break
return res
def sample(self, batch_size, beta, pretrain=False):
idxes = self._sample_proportional(batch_size, pretrain)
# demos is a bool
demos = [i < self.num_demonstrations for i in idxes]
weights = []
p_sum = self._it_sum.sum()
# 算重要性采样权重 weights
for idx in idxes:
p_sample = self._it_sum[idx] / p_sum
weight = ((1.0 / p_sample) * (1.0 / len(self.storage)))**beta
weights.append(weight)
weights = np.array(weights) / np.max(weights)
encoded_sample = self._get_batches_for_idxes(idxes)
encoded_sample['weights'] = array_min2d(weights)
encoded_sample['idxes'] = array_min2d(idxes)
encoded_sample['demos'] = array_min2d(demos)
return encoded_sample
def sample_rollout(self, batch_size, nsteps, beta, gamma, pretrain=False):
batches = self.sample(batch_size, beta, pretrain)
n_step_batches = {
storable_element: []
for storable_element in self.storable_elements
}
n_step_batches["step_reached"] = []
idxes = batches["idxes"]
for idx in idxes:
local_idxes = list(
range(int(idx), int(min(idx + nsteps, len(self)))))
transitions = self._get_batches_for_idxes(local_idxes)
summed_reward = 0
count = 0
terminal = 0.0
terminals = transitions['terminals1']
r = transitions['rewards']
for i in range(len(r)):
summed_reward += (gamma**i) * r[i][0]
count = i
if terminals[i]:
terminal = 1.0
break
n_step_batches["step_reached"].append(count)
n_step_batches["obs1"].append(transitions["obs1"][count])
n_step_batches["f_s1"].append(transitions["f_s1"][count])
n_step_batches["terminals1"].append(terminal)
n_step_batches["rewards"].append(summed_reward)
n_step_batches["actions"].append(transitions["actions"][0])
n_step_batches['demos'] = batches['demos']
n_step_batches['weights'] = batches['weights']
n_step_batches['idxes'] = idxes
n_step_batches = {k: array_min2d(v) for k, v in n_step_batches.items()}
return batches, n_step_batches, sum(batches['demos']) / batch_size
def update_priorities(self, idxes, td_errors, actor_losses=0.0):
priorities = td_errors + \
(actor_losses ** 2) + self._transition_small_epsilon
for i in range(len(priorities)):
if idxes[i] < self.num_demonstrations:
priorities[i] += np.max(priorities) * self._demo_epsilon
assert len(idxes) == len(priorities)
for idx, priority in zip(idxes, priorities):
assert priority > 0
assert 0 <= idx < len(self.storage)
idx = int(idx)
self._it_sum[idx] = priority**self._alpha
self._it_min[idx] = priority**self._alpha
self._max_priority = max(self._max_priority, priority**self._alpha)
self.help.append(priority**self._alpha)