class PriorityReplayMemory(ReplayMemory):
def __init__(self, size, alpha):
super().__init__(size)
self.alpha = alpha
tree_cap = 1
while tree_cap < size:
tree_cap *= 2
self.sum_tree = SumSegmentTree(tree_cap)
self.max_priority = 1.0
def add_mem(self, *args, **kwargs):
idx = self.next_idx
super().add_mem(*args, **kwargs)
prio = self.max_priority**self.alpha
self.sum_tree[idx] = prio
def _sample_idxs(self, size):
idxs = []
for _ in range(size):
mass = random.random() * self.sum_tree.sum(0, len(self.memory) - 1)
idx = self.sum_tree.find_prefixsum_idx(mass)
idxs.append(idx)
return idxs
def get_batch(self, size, beta):
assert beta > 0
idxs = self._sample_idxs(size)
# create weights:
weights = []
tot_sum = self.sum_tree.sum()
#p_min = tot_min / tot_sum
#max_w = (p_min * len(self.memory)) ** (-beta)
for idx in idxs:
p_sample = self.sum_tree[idx] / tot_sum
weight = (p_sample * len(self.memory))**(-beta)
weights.append(weight)
#print(max_w)
#print(weights)
weights = np.array(weights)
weights /= max(weights)
batch = [self.memory[idx] for idx in idxs]
return batch, weights, idxs
def update_priorities(self, idxs, priorities):
for idx, prio in zip(idxs, priorities):
assert prio > 0
prio_a = prio**self.alpha
self.sum_tree[idx] = prio_a
self.max_priority = max(self.max_priority, prio)
class PrioritizedReplayBuffer(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, *args, **kwargs):
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 = []
p_total = self._it_sum.sum(0, len(self._storage) - 1)
every_range_len = p_total / batch_size
for i in range(batch_size):
mass = random.random() * every_range_len + i * every_range_len
idx = self._it_sum.find_prefixsum_idx(mass)
res.append(idx)
return res
def sample(self, batch_size, beta):
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):
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 PrioritizedReplayBuffer(ReplayBuffer):
def __init__(self, memory_size=1000000, alpha=0.5, seed=None):
'''
Prioritized replay buffer from https://arxiv.org/pdf/1511.05952.pdf
This implementation is based on the OpenAI sumtree implemenation which can be found here
https://github.com/openai/baselines/blob/master/baselines/deepq/replay_buffer.py
memory_size: int
maximum number of experiences to store
alpha: float, [0.0, 1.0]
hyperparameter that controls the amount of prioritization, with 0.0 being
no prioritization (the uniform case)
seed: None or int
random seed for the replay buffer
'''
super().__init__(memory_size=memory_size, seed=seed)
self.alpha = alpha
it_capacity = 1
while it_capacity < self._memory_size:
it_capacity *= 2
self._it_sum = SumSegmentTree(it_capacity)
self._it_min = MinSegmentTree(it_capacity)
self._max_priority = 1.0
def add(self, experience):
'''
Add an experience to the replay buffer
experience: object, usually a tuple
the experience to store in the replay buffer
this implementation does not specify a form for the experience as all that is handled by the DQN agent
'''
index = self._next_index
super().add(experience)
self._it_sum[index] = self._max_priority**self.alpha
self._it_min[index] = self._max_priority**self.alpha
def _sample_proportional(self, batch_size):
'''
Function to use sample from the replay buffer with proportional prioritization
All code here is from the OpenAI implementation to correctly make use of the
sum-tree data structure
batch_size: int
then number of experience to sample
res: list
list of indices of the experiences sampled from the replay buffer
'''
res = []
p_total = self._it_sum.sum(0, len(self._memory) - 1)
every_range_len = p_total / batch_size
for i in range(batch_size):
mass = random.random() * every_range_len + i * every_range_len
index = self._it_sum.find_prefixsum_idx(mass)
res.append(index)
return res
def sample(self, batch_size, beta=1.0):
'''
Sample from the replay buffer with proportional prioritization
batch_size: int
then number of experience to sample
samples: list of 3-tuples
list of sampled experiences, importance sampling weights for each experience, and
the indices of the experiences (used to update priorities) in the form
(experience, is_weights, indices)
'''
indices = self._sample_proportional(batch_size)
weights = []
p_min = self._it_min.min() / self._it_sum.sum()
max_weight = (p_min * len(self._memory))**(-beta)
samples = []
for i in indices:
p_sample = self._it_sum[i] / self._it_sum.sum()
is_weight = ((p_sample * len(self._memory))**(-beta)) / max_weight
experience = self._memory[i]
sample = (experience, is_weight, i)
samples.append(sample)
return samples
def update_priorities(self, indices, priorities):
'''
Update the priorities for the experiences corresponding to the given indices
indices: list-like
list of indices for the experiences/priorities to update
priorities: list-like
list of new priorities corresponding to the given indices
'''
for i, priority in zip(indices, priorities):
self._it_sum[i] = priority**self.alpha
self._it_min[i] = priority**self.alpha
self._max_priority = max(self._max_priority, priority)
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):
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].
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):
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 PrioritizedReplayBuffer(ReplayBuffer):
def __init__(self, size, alpha):
"""
Prioritied Experience Replay
"""
super(PrioritizedReplayBuffer, self).__init__(size)
assert alpha > 0
self._alpha = alpha
# I don't understand purpose of this
# maybe to create a graph to store ranked truples?
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):
idx = self._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):
mass = random.random() * self._it_sum.sum(0, len(self._buffer) - 1)
idx = self._it_sum.find_prefixsum_idx(mass)
res.append(idx)
return res
def sample(self, batch_size, beta):
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._buffer))**(-beta)
for idx in idxes:
p_sample = self._it_sum[idx] / self._it_sum.sum()
weight = (p_sample * len(self._buffer))**(-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):
"""
set priority of transition at index idxes[i] in buffer to priorities[i]
"""
assert len(idxes) == len(priorities)
for idx, priority in zip(idxes, priorities):
assert priority > 0
assert 0 <= idx < len(self._buffer)
self._it_sum[idx] = priority**self._alpha
self._it_min[idx] = priority**self._alpha
self._max_priority = max(self._max_priority, priority)
class ProportionalReplay(ExperienceReplay):
def __init__(self, size, alpha):
super(ProportionalReplay, self).__init__(size)
assert alpha >= 0
self.alpha = alpha
self.tree_size = 1
while self.tree_size < self.maxsize:
self.tree_size *= 2
self.min_tree = MinSegmentTree(
self.tree_size) # for calculating maximum IS weight
self.sum_tree = SumSegmentTree(
self.tree_size) # for proportional sampling
self.max_priority = 1.0 # maximum priority we've seen so far. will be updated
def add(self, experience):
idx = self.next_idx # save idx before it's changed in super call
super().add(
experience) # put experience data (s,a,r,s',done) in buffer
# give new experience max priority to ensure it's replayed at least once
self.min_tree[idx] = self.max_priority**self.alpha
self.sum_tree[idx] = self.max_priority**self.alpha
# To sample a minibatch of size k, the range [0, p_total] is divided equally into k ranges.
# Next, a value is uniformly sampled from each range.
def sample_proportional(self, batch_size):
idxs = []
p_total = self.sum_tree.sum(
0,
len(self.buffer) -
1) # sum of the priorities of all experience in the buffer
every_range_len = p_total / batch_size # length of every range over [0,p_total] (batch_size = k)
for i in range(batch_size): # for each range
mass = self.np_random.uniform(
) * every_range_len + i * every_range_len # uniformly sampling a probability mass from this range
idx = self.sum_tree.find_prefixsum_idx(
mass
) # get smallest experience index s.t. cumulative dist F(idx) >= mass
idxs.append(idx)
return idxs
# sample batch of experiences along with their weights and indices
def sample(self, batch_size, beta):
assert beta > 0
idxs = self.sample_proportional(
batch_size) # sampled experience indices
weights = []
p_min = self.min_tree.min() / self.sum_tree.sum(
) # minimum possible priority for a transition
max_weight = (p_min * len(self.buffer))**(
-beta) # (p_uniform/p_min)^beta is maximum possible IS weight
# get IS weights for sampled experience
for idx in idxs:
p_sample = self.sum_tree[idx] / self.sum_tree.sum(
) # normalize sampled priority
weight = (p_sample * len(self.buffer))**(
-beta) # (p_uniform/p_sample)^beta. IS weight
weights.append(
weight / max_weight
) # weights normalized by max so that they only scale the update downwards
weights = np.array(weights)
encoded_sample = self.encode_samples(
idxs) # collect experience at given indices
return tuple(list(encoded_sample) + [weights, idxs])
# set the priorities of experiences at given indices
def update_priorities(self, idxs, priorities):
assert len(idxs) == len(priorities)
for idx, priority in zip(idxs, priorities):
assert priority > 0
assert 0 <= idx < len(self.buffer)
self.sum_tree[idx] = priority**self.alpha
self.min_tree[idx] = priority**self.alpha
self.max_priority = max(self.max_priority, priority)
class PrioritizedReplayBuffer(ReplayBuffer):
"""Fixed-size prioritized buffer to store experience tuples."""
def __init__(self, action_size, buffer_size, batch_size, seed, alpha=0.6, beta=0.5, device="cpu"):
"""Initialize a PrioritizedReplayBuffer object.
Params
======
action_size (int): dimension of each action
buffer_size (int): maximum size of buffer
batch_size (int): size of each training batch
seed (int): random seed
alpha (float): how much prioritization is used (0 - no prioritization, 1 - full prioritization)
beta (float): To what degree to use importance weights (0 - no corrections, 1 - full correction)
"""
super(PrioritizedReplayBuffer, self).__init__(action_size, buffer_size, batch_size, seed, device=device)
self.alpha = alpha
self.beta = beta
self._eps = 0.00000001
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
def add(self, state, action, reward, next_state, done):
"""Add a new experience to memory."""
idx = self._next_idx
super().add(state, action, reward, next_state, done)
self._it_sum[idx] = self._max_priority ** self.alpha
self._it_min[idx] = self._max_priority ** self.alpha
def _sample_proportional(self):
res = []
p_total = self._it_sum.sum(0, len(self.memory) - 1)
every_range_len = p_total / self.batch_size
for i in range(self.batch_size):
mass = random.random() * every_range_len + i * every_range_len
idx = self._it_sum.find_prefixsum_idx(mass)
res.append(idx)
return res
def sample(self):
idxes = self._sample_proportional()
weights = []
p_min = self._it_min.min() / self._it_sum.sum()
max_weight = (p_min * len(self.memory) + self._eps) ** (-self.beta)
for idx in idxes:
p_sample = self._it_sum[idx] / self._it_sum.sum()
weight = (p_sample * len(self.memory) + self._eps) ** (-self.beta)
weights.append(weight / max_weight)
weights = torch.tensor(weights, device=self.device, dtype=torch.float)
states = torch.from_numpy(np.vstack([self.memory[i].state for i in idxes])).float().to(self.device)
actions = torch.from_numpy(np.vstack([self.memory[i].action for i in idxes])).long().to(self.device)
rewards = torch.from_numpy(np.vstack([self.memory[i].reward for i in idxes])).float().to(self.device)
next_states = torch.from_numpy(np.vstack([self.memory[i].next_state for i in idxes])).float().to(self.device)
dones = torch.from_numpy(np.vstack([self.memory[i].done for i in idxes]).astype(np.uint8)).float().to(self.device)
return (states, actions, rewards, next_states, dones, idxes, weights)
def update_priorities(self, indexes, priorities):
"""Update priorities of sampled transitions.
sets priority of transition at index indexes[i] in buffer
to priorities[i].
Parameters
----------
indexes: [int]
List of idxes of sampled transitions
priorities: [float]
List of updated priorities corresponding to
transitions at the sampled idxes denoted by
variable `idxes`.
"""
for idx, priority in zip(indexes, priorities):
self._it_sum[idx] = priority ** self.alpha
self._it_min[idx] = priority ** self.alpha
self._max_priority = max(self._max_priority, priority)
class PrioritizedReplayBuffer(ReplayBuffer):
def __init__(self,
size,
state_shape,
alpha,
n_batch_trajectories,
n_trajectory_steps,
n_emus=1):
"""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.
dsize: int
Max number of demonstration transitions. These are retained in the
buffer permanently.
https://arxiv.org/abs/1704.03732
alpha: float
how much prioritization is used
(0 - no prioritization, 1 - full prioritization)
See Also
--------
ReplayBuffer.__init__
"""
super(PrioritizedReplayBuffer, self).__init__(size,
state_shape,
n_batch_trajectories,
n_trajectory_steps,
n_emus=n_emus)
assert alpha > 0
self._alpha = alpha
it_capacity = 1
while it_capacity < self._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.add_effect"""
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, self._size - 1)
idx = self._it_sum.find_prefixsum_idx(mass)
res.append(idx)
return np.array(res)
def _compute_weights(self, idxes, beta):
weights = []
p_min = self._it_min.min() / self._it_sum.sum()
max_weight = (p_min * self._size)**(-beta)
for idx in idxes:
if idx < 0:
weights.append(0.0)
continue
p_sample = self._it_sum[idx] / self._it_sum.sum()
weight = (p_sample * self._size)**(-beta)
weights.append(weight / max_weight)
return np.array(weights)
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
rew_batch: np.array
rewards received as results of executing act_batch
next_obs_batch: np.array
next set of observations seen after executing act_batch
done_mask: np.array
done_mask[i] = 1 if executing act_batch[i] resulted in
the end of an episode and 0 otherwise.
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
"""
assert beta > 0
idxes = self._sample_proportional(batch_size)
batch_samples = self._retrieve_samples(idxes)
weights = self._compute_weights(idxes, beta)
return tuple(list(batch_samples) + [weights, idxes])
def sample_nstep(self, beta):
"""Sample a (self.n_batch_trajectories, self.n_trajectory_steps, n_s) batch of states, where n_s is the dimension of the
state vector
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)
n_step: int
How many steps to look into the future
Returns
-------
obs_batch: np.array
batch of observations
act_batch: np.array
batch of actions executed given obs_batch
rew_batch: np.array
rewards received as results of executing act_batch
next_obs_batch: np.array
next set of observations seen after executing act_batch
done_mask: np.array
done_mask[i] = 1 if executing act_batch[i] resulted in
the end of an episode and 0 otherwise.
n_step_rewards_batch: np.array
n-step rewards vector batch
tpn_obs_batch: np.array
tpn set of observations
n_tpn_step_batch: np.array
n in n-step indicator to indicate if trajectory sampled
is unfinished or done -- trajectory is unfinished if
there are no more transitions to cover all n steps
n_step_done_mask: np.array
n_step_done_mask[i] = 1 if trajectory sampled reaches
the end of an episode, and 0 otherwise.
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
"""
assert beta > 0
traj_idxes = self._sample_proportional(self.n_batch_trajectories)
batched_trajectories, idxes = self._retrieve_n_step_trajectories(
traj_idxes)
#for i in idxes:
# if i == -1: continue
# assert self.traj_ids[i] > -1
weights = self._compute_weights(idxes, beta)
return batched_trajectories + (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):
if idx < 0:
continue
assert priority > 0
assert 0 <= idx < self._size
self._it_sum[idx] = priority**self._alpha
self._it_min[idx] = priority**self._alpha
self._max_priority = max(self._max_priority, priority)
class PriorityBuffer(BufferBase):
def __init__(self, capacity, gamma=0.99, n_steps=2, alpha=0.5):
super(PriorityBuffer, self).__init__(capacity, gamma, n_steps)
self.buffer = []
self.position = 0
self.alpha = alpha
it_cap = 1
while it_cap < capacity:
it_cap *= 2
self._it_sum = SumSegmentTree(it_cap)
self._it_min = MinSegmentTree(it_cap)
self._max_priority = 1.0
def __len__(self):
return len(self.buffer)
def append(self, experience):
position = self.position
if len(self.buffer) < self.capacity:
self.buffer.append(experience)
else:
self.buffer[position] = experience
self.position = (position + 1) % self.capacity
self._it_sum[position] = self._max_priority**self.alpha
self._it_min[position] = self._max_priority**self.alpha
def _sample_proportional(self, batch_size):
total = self._it_sum.sum(0, len(self.buffer) - (1 + self.n_steps))
mass = np.random.random(size=batch_size) * total
idx = self._it_sum.find_prefix_sum_idx(mass)
return idx
def sample(self, batch_size, beta=0.4):
assert beta > 0
indices = self._sample_proportional(batch_size)
states = []
actions = []
rewards = []
dones = []
next_states = []
for index in indices:
current_buffer = self.buffer[index]
current_state = current_buffer[0]
current_action = current_buffer[1]
current_done = current_buffer[3]
reward = current_buffer[2]
next_state = self.buffer[index + self.n_steps][0]
for sub_index in range(1, self.n_steps):
reward += self.buffer[index + sub_index][2] * (self.gamma**
sub_index)
if self.buffer[index + sub_index][3]:
break
states.append(ar(current_state, dtype=np.float32))
actions.append(current_action)
rewards.append(reward)
dones.append(current_done)
next_states.append(ar(next_state, dtype=np.float32))
sm = self._it_sum.sum()
p_min = self._it_min.min() / sm
max_weight = (p_min * len(self.buffer))**(-beta)
p_sample = self._it_sum[indices] / sm
weights = (p_sample * len(self.buffer))**(-beta) / max_weight
states_np = np.stack(states, 0) / 255.0
next_states_np = np.stack(next_states, 0) / 255.0
return states_np, ar(actions), ar(rewards, dtype=np.float32), ar(dones, dtype=np.uint8), next_states_np, \
ar(weights, dtype=np.float32), indices
def update_weights(self, batch_indices, batch_priorities):
assert len(batch_indices) == len(batch_priorities)
assert np.min(batch_priorities) > 0
assert np.min(batch_indices) >= 0
for idx, prio in zip(batch_indices, batch_priorities):
idx = int(idx)
self._it_sum[idx] = prio**self.alpha
self._it_min[idx] = prio**self.alpha
self._max_priority = max(self._max_priority, np.max(batch_priorities))
class PrioritizedReplayBuffer(ReplayBuffer):
def __init__(self, action_size, buffer_size, batch_size, seed, alpha=0.6):
super(PrioritizedReplayBuffer, self).__init__(action_size, buffer_size, batch_size, seed)
#capacity must be positive and a power of 2
tree_capacity = 1
while tree_capacity < self.buffer_size:
tree_capacity *= 2
self.sum_tree = SumSegmentTree(tree_capacity)
self.min_tree = MinSegmentTree(tree_capacity)
self.max_priority, self.tree_ptr = 1.0, 0
self.alpha = alpha
def add(self, state, action, reward, next_state, done):
self.sum_tree[self.tree_ptr] = self.max_priority**self.alpha
self.min_tree[self.tree_ptr] = self.max_priority**self.alpha
super().add(state, action, reward, next_state, done)
self.tree_ptr = (self.tree_ptr + 1) % self.buffer_size
# if self.tree_ptr == self.buffer_size-1:
# for i in range(0, self.buffer_size-1):
# self.sum_tree[i] = self.sum_tree[i+1]
# self.min_tree[i] = self.min_tree[i+1]
# self.sum_tree[self.tree_ptr] = self.max_priority**self.alpha
# self.min_tree[self.tree_ptr] = self.max_priority**self.alpha
# else:
#
def sample(self, beta=0.4):
indices = self._sample_proportional()
indices = [index for index in indices if index<len(self.memory)]
states = torch.from_numpy(np.vstack([self.memory[index].state for index in indices])).float().to(device)
actions = torch.from_numpy(np.vstack([self.memory[index].action for index in indices])).long().to(device)
rewards = torch.from_numpy(np.vstack([self.memory[index].reward for index in indices])).float().to(device)
next_states = torch.from_numpy(np.vstack([self.memory[index].next_state for index in indices])).float().to(device)
dones = torch.from_numpy(np.vstack([self.memory[index].done for index in indices]).astype(np.uint8)).float().to(device)
weights = torch.from_numpy(np.vstack([self._cal_weight(index, beta) for index in indices])).float().to(device)
return (states, actions, rewards, next_states, dones, weights, indices)
def update_priority(self, indices, loss_for_prior):
for idx, priority in zip(indices, loss_for_prior):
self.sum_tree[idx] = priority ** self.alpha
self.min_tree[idx] = priority ** self.alpha
self.max_priority = max(self.max_priority, priority)
def _sample_proportional(self):
indices = []
p_total = self.sum_tree.sum() #sum(0, len(self.memory)-1)
segment = p_total / self.batch_size
for i in range(self.batch_size):
start = segment * i
end = start + segment
upper = random.uniform(start, end)
index = self.sum_tree.retrieve(upper)
indices.append(index)
return indices
def _cal_weight(self, index, beta):
sum_priority = self.sum_tree.sum()
min_priority = self.min_tree.min()
current_priority = self.sum_tree[index]
# max_w = (len(self.memory) * (min_priority/sum_priority)) ** (-beta)
# current_w = (len(self.memory) * (current_priority/sum_priority)) ** (-beta)
# return current_w / max_w
return (min_priority / current_priority) ** beta
class PERBuffer:
# Simple class that holds the different types of memory
class Memory:
# Expects all shapes to be tuples, size to be an integer
def __init__(self, state_shape, action_shape, size):
self.states = np.zeros((size, ) + state_shape)
self.actions = np.zeros((size, ) + action_shape)
self.rewards = np.zeros(size)
self.next_states = np.zeros((size, ) + state_shape)
self.dones = np.zeros(size)
self.size = size
# memory[i] will return a tuple of the entire memory @ i
def __getitem__(self, key):
return (self.states[key], self.actions[key], self.rewards[key],
self.next_states[key], self.dones[key])
# Provides a quick way of updating multiple
# parts of memory at a specific index
def update(self,
indx,
state=None,
action=None,
reward=None,
next_state=None,
done=None):
self.states[indx] = state
self.actions[indx] = action
self.rewards[indx] = reward
self.next_states[indx] = next_state
self.dones[indx] = done
# An alternative to __getitem__, returns dict instead
def get(self, key):
rtn = {
"states": self.states[key],
"actions": self.actions[key],
"rewards": self.rewards[key],
"next_states": self.next_states[key],
"dones": self.dones[key]
}
return rtn
# Creates the replay buffer
def __init__(self,
state_shape,
action_shape,
size,
alpha=0.6,
beta=0.4,
beta_delta=0.001,
epsilon=0.01):
self.memory = self.Memory(state_shape, action_shape, size)
self.counter = 0
self.size = self.memory.size
# Segment trees
self.sum_tree = SumSegmentTree(self.size)
self.min_tree = MinSegmentTree(self.size)
# P.E.R. hyperparameters
self.alpha = alpha
self.beta = beta
self.beta_delta = beta_delta
self.epsilon = epsilon
self.max_priority = 1.0
# Samples the indexes from memory in accordance to their priority
def sample_indexes(self, batch_size, max_memory):
sample_indexes = np.zeros(shape=batch_size)
# Gets the total probability of all used memory
prob_total_norm = self.sum_tree.sum(0, max_memory - 1) / batch_size
# Gets indexes using probability
for i in range(batch_size):
# ---VAL MAY NEED TO BE CHANGED---
val = random.random() * prob_total_norm + i * prob_total_norm
indx = self.sum_tree.find_prefixsum_idx(val)
sample_indexes[i] = indx
return sample_indexes
# Stores new memory at looping index
def store(self, state, action, reward, next_state, done):
indx = self.counter % self.size
self.memory.update(indx, state, action, reward, next_state, done)
# Gets the priority alpha for the newly added sample
priority_alpha = self.max_priority**self.alpha
# Adds this to the sum and min trees
self.sum_tree[indx] = priority_alpha
self.min_tree[indx] = priority_alpha
# Updates the counter
self.counter += 1
# Samples the memory from filled parts of the buffer
# Returns a tuple (states, actions, rewards, next_states, dones, weights)
def miniBatch(self, batch_size):
max_memory = min(self.counter, self.size)
# Samples the indexes according to their importance
batch_indxs = self.sample_indexes(batch_size, max_memory)
batch_indxs = np.int_(batch_indxs)
# Gets the weights
weights = np.zeros(shape=batch_size)
prob_min = self.min_tree.min() / (self.sum_tree.sum() + self.epsilon)
max_weight = (prob_min * max_memory)**(-self.beta)
for i in range(0, len(batch_indxs)):
prob = self.sum_tree[batch_indxs[i]] / \
(self.sum_tree.sum() + self.epsilon)
weight = (prob * max_memory)**(-self.beta)
weight_norm = weight / (max_weight + self.epsilon)
weights[i] = weight_norm
# Updates beta
self.beta = min(1.0, self.beta + self.beta_delta)
# Returns memory and weights and idxs
return self.memory[batch_indxs] + (weights, ) + (batch_indxs, )
# for given indexes and priorities, updates the trees and max
def update_priorities(self, indxs, priorities):
for indx, priority in zip(indxs, priorities):
priority_alpha = priority**self.alpha
self.sum_tree[indx] = priority_alpha[0]
self.min_tree[indx] = priority_alpha[0]
# Sets the max priority to be newest max
self.max_priority = max(self.max_priority, priority)
class ReplayMemory:
def __init__(self, replay_size, alpha=0.6):
self.replay_size = replay_size
self.cnt = 0
self._alpha = alpha
it_capacity = 1
while it_capacity < replay_size:
it_capacity *= 2
self._it_sum = SumSegmentTree(it_capacity)
self._it_min = MinSegmentTree(it_capacity)
self._max_priority = 1.0
self._storage = []
self._maxsize = replay_size
self._next_idx = 0
def add(self, data):
#new_data = []
#for i in data:
# i.wait_to_read()
# new_data.append(copyto(i))
if self._next_idx >= len(self._storage):
self._storage.append(data)
#print self._storage
else:
self._storage[self._next_idx] = data
self._next_idx = (self._next_idx + 1) % self._maxsize
idx = self._next_idx
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):
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=0.4):
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)
#print self._it_min.min(), weights
weights = np.array(weights)
weights /= np.sum(weights)
ret = []
for i in xrange(batch_size):
ret.append(self._storage[idxes[i]])
return (ret, idxes, weights)
def update_priorities(self, idxes, priorities):
assert len(idxes) == len(priorities)
for idx, priority in zip(idxes, priorities):
#print priority
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 PrioritizedReplay(Replay):
def __init__(self, learner_config, env_config, session_config):
"""
Create Prioritized Replay buffer.
: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__(learner_config=learner_config,
env_config=env_config,
session_config=session_config)
self._alpha = self.replay_config.alpha
assert self._alpha > 0
self._memory = []
self.memory_size = self.replay_config.memory_size
it_capacity = 1
while it_capacity < self.memory_size:
it_capacity *= 2
self._it_sum = SumSegmentTree(it_capacity)
self._it_min = MinSegmentTree(it_capacity)
self._max_priority = 1.0
def default_config(self):
conf = super().default_config()
conf.update({
'memory_size': '_int_',
'sampling_start_size': '_int_',
'alpha': '_float_',
})
return conf
def insert(self, exp_dict):
"""
Adds experience to the replay buffer as usual, but also
intiialize the priority of the new experience.
"""
with self.insert_time.time():
if self._next_idx >= len(self._memory):
self._memory.append(exp_dict)
else:
self._memory[self._next_idx] = exp_dict
self._next_idx = (self._next_idx + 1) % self.memory_size
idx = self._next_idx
self._it_sum[idx] = self._max_priority**self._alpha
self._it_min[idx] = self._max_priority**self._alpha
def sample(self, batch_size, beta=0):
"""
WARNING: This function does not make deep copies of the tuple experiences.
This means that if any objects in the experiences are modified,
the contents of the replay buffer memory will also be modified,
so be careful!!!
Sample a batch of experiences, along with their importance weights, and the
indices of the sampled experiences in the buffer.
: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 experience_batch: List
List of tuples, length batch_size, corresponding to the experiences sampled.
:return weights: np.array
Array of shape (batch_size,) and dtype np.float32
denoting importance weight of each sampled transition
:return indices: np.array
Array of shape (batch_size,) and dtype np.int32
indices in buffer of sampled experiences
"""
with self.sample_time.time():
assert beta >= 0
# sample the experiences proportional to their priorities
indices = self._sample_proportional(batch_size)
response = [self._storage[idx] for idx in indices]
# compute importance weights for the experiences to correct for distribution shift
weights = []
p_min = self._it_min.min() / self._it_sum.sum()
max_weight = (p_min * len(self._storage))**(-beta)
for idx in indices:
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)
# return response, weights, indices
return response
def _sample_proportional(self, batch_size):
"""
This is a helper function to sample expriences with probabilities
proportional to their priorities.
Returns a list of indices.
"""
res = []
for _ in range(batch_size):
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 update_priorities(self, indices, priorities):
"""
Update priorities of sampled transitions.
sets priority of transition at index indices[i] in buffer
to priorities[i].
:param indices: [int]
List of indices of sampled transitions
:param priorities: [float]
List of updated priorities corresponding to
transitions at the sampled indices denoted by
variable `indices`.
"""
assert len(indices) == len(priorities)
for idx, priority in zip(indices, 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)
def evict(self):
raise NotImplementedError # TODO
# if evict_size > len(self._memory):
# evicted = self._memory
# self._memory = []
# self._next_idx = 0
# return evicted
# forward_space = len(self._memory) - self._next_idx
# if evict_size < forward_space:
# evicted = self._memory[self._next_idx:self._next_idx+evict_size]
# del self._memory[self._next_idx:self._next_idx+evict_size]
# else:
# evicted = self._memory[self._next_idx:]
# evict_from_left = evict_size - forward_space
# evicted += self._memory[:evict_from_left]
# del self._memory[self._next_idx:]
# del self._memory[:evict_from_left]
# self._next_idx -= evict_from_left
# assert len(evicted) == evict_size
# return evicted
def start_sample_condition(self):
return len(self) > self.replay_config.sampling_start_size
def __len__(self):
return len(self._memory)
class PrioritizedReplayBuffer(SimpleReplayBuffer):
def __init__(self, MAX_LEN, alpha: float = 0.6):
"""
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
--------
SimpleReplayBuffer.__init__
"""
super(PrioritizedReplayBuffer, self).__init__(MAX_LEN)
assert alpha >= 0
self._alpha = alpha
it_capacity = 1
while it_capacity < MAX_LEN:
it_capacity *= 2
self._it_sum = SumSegmentTree(it_capacity)
self._it_min = MinSegmentTree(it_capacity)
self._max_priority = 1.0
def add(self, experience: Experience):
"""See SimpleReplayBuffer.store_effect"""
idx = self._next_idx
super().add(experience)
self._it_sum[idx] = self._max_priority**self._alpha
self._it_min[idx] = self._max_priority**self._alpha
def _sample_proportional(self, batch_size: int) -> List[int]:
res = []
p_total = self._it_sum.sum(0, len(self._storage) - 1)
every_range_len = p_total / batch_size
for i in range(batch_size):
mass = random() * every_range_len + i * every_range_len
idx = self._it_sum.find_prefixsum_idx(mass)
res.append(idx)
return res
def sample(
self,
batch_size: int,
beta: float = 0.4
) -> Tuple[List[Experience], np.ndarray, List[int]]: # type: ignore
"""Sample a batch of experiences.
compared to SimpleReplayBuffer.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
-------
experiences: List[Experience]
batch of experiences
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
"""
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 (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):
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 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
rew_batch: np.array
rewards received as results of executing act_batch
next_obs_batch: np.array
next set of observations seen after executing act_batch
done_mask: np.array
done_mask[i] = 1 if executing act_batch[i] resulted in
the end of an episode and 0 otherwise.
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
"""
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].
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):
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 ReplayMemory(ReplayBuffer):
def __init__(self, size, alpha):
super().__init__(size, N_Step_Transition)
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 put(self, transitions, priorities):
idxes = []
for transition in transitions:
idx = self.next_idx
super().put(transition)
idxes.append(idx)
self.update_priorities(idxes, priorities)
def _sample_proportional(self, batch_size):
res = []
p_total = self._it_sum.sum(0, len(self.buffer) - 1)
every_range_len = p_total / batch_size
for i in range(batch_size):
mass = random.random() * every_range_len + i * every_range_len
idx = self._it_sum.find_prefixsum_idx(mass)
res.append(idx)
return res
def _encode_sample(self, idxes):
s_lst, a_lst, r_lst, next_state_lst, done_mask_lst = [], [], [], [], []
n_step_transitions = N_Step_Transition(*zip(
*[self.buffer[index] for index in idxes]))
# 'S_t', 'A_t', 'R_ttpB', 'Gamma_ttpB', 'qS_t', 'S_tpn', 'qS_tpn', 'key'
S_t = np.array(n_step_transitions.S_t)
S_tpn = np.array(n_step_transitions.S_tpn)
R_ttpB = np.array(n_step_transitions.R_ttpB)
gamma_ttpB = np.array(n_step_transitions.Gamma_ttpB)
qS_tpn = np.array(n_step_transitions.qS_tpn)
A_t = np.array(n_step_transitions.A_t, dtype=np.int)
qS_t = np.array(n_step_transitions.qS_t)
key = np.array(n_step_transitions.key)
return S_t, A_t, R_ttpB, S_tpn, gamma_ttpB, qS_tpn, qS_t, key
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
rew_batch: np.array
rewards received as results of executing act_batch
next_obs_batch: np.array
next set of observations seen after executing act_batch
done_mask: np.array
done_mask[i] = 1 if executing act_batch[i] resulted in
the end of an episode and 0 otherwise.
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
"""
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.buffer))**(-beta)
for idx in idxes:
p_sample = self._it_sum[idx] / self._it_sum.sum()
weight = (p_sample * len(self.buffer))**(-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].
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):
assert priority > 0
assert 0 <= idx < len(self.buffer)
self._it_sum[idx] = priority**self._alpha
self._it_min[idx] = priority**self._alpha
self._max_priority = max(self._max_priority, priority)
def remove_old_experience(self):
if self.size() > self.maxsize:
num_excess = self.size() - self.maxsize
# FIFO
del self.buffer[:num_excess]
class PrioritizedReplayMemory:
def __init__(self, size, alpha=0.6, beta_start=0.4, beta_frames=100000):
super(PrioritizedReplayMemory, self).__init__()
self._storage = []
self._maxsize = size
self._next_idx = 0
assert alpha >= 0
self._alpha = alpha
self.beta_start = beta_start
self.beta_frames = beta_frames
self.frame = 1
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
self.experience = namedtuple(
"Experience",
field_names=["state", "action", "reward", "next_state", "done"])
def beta_by_frame(self, frame_idx):
return min(
1.0, self.beta_start + frame_idx *
(1.0 - self.beta_start) / self.beta_frames)
def push(self, state, action, reward, next_state, done):
idx = self._next_idx
exp = self.experience(state, action, reward, next_state, done)
if self._next_idx >= len(self._storage):
self._storage.append(exp)
else:
self._storage[self._next_idx] = exp
self._next_idx = (self._next_idx + 1) % self._maxsize
self._it_sum[idx] = self._max_priority**self._alpha
self._it_min[idx] = self._max_priority**self._alpha
def _encode_sample(self, idxes):
states = torch.from_numpy(
np.array([self._storage[i].state
for i in idxes])).float().to(device)
actions = torch.from_numpy(
np.array([self._storage[i].action
for i in idxes])).float().to(device)
rewards = torch.from_numpy(
np.array([self._storage[i].reward
for i in idxes])).float().to(device)
next_states = torch.from_numpy(
np.array([self._storage[i].next_state
for i in idxes])).float().to(device)
dones = torch.from_numpy(
np.array([self._storage[i].done
for i in idxes]).astype(np.uint8)).float().to(device)
return (states, actions, rewards, next_states, dones)
def _sample_proportional(self, batch_size):
res = []
for _ in range(batch_size):
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):
idxes = self._sample_proportional(batch_size)
weights = []
#find smallest sampling prob: p_min = smallest priority^alpha / sum of priorities^alpha
p_min = self._it_min.min() / self._it_sum.sum()
beta = self.beta_by_frame(self.frame)
self.frame += 1
#max_weight given to smallest prob
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 = torch.tensor(weights, device=device, dtype=torch.float)
encoded_sample = self._encode_sample(idxes)
return encoded_sample, idxes, weights
def update_priorities(self, idxes, priorities):
assert len(idxes) == len(priorities)
for idx, priority in zip(idxes, priorities):
assert 0 <= idx < len(self._storage)
self._it_sum[idx] = (priority + 1e-5)**self._alpha
self._it_min[idx] = (priority + 1e-5)**self._alpha
self._max_priority = max(self._max_priority, (priority + 1e-5))
class ReplayMemory:
def __init__(self, replay_size, alpha=0.6):
self.replay_size = replay_size
self.cnt = 0
self._alpha = alpha
it_capacity = 1
while it_capacity < replay_size:
it_capacity *= 2
self._it_sum = SumSegmentTree(it_capacity)
self._it_min = MinSegmentTree(it_capacity)
self._max_priority = 1.0
self._storage = []
self._maxsize = replay_size
self._next_idx = 0
def add(self, data):
#new_data = []
#for i in data:
# i.wait_to_read()
# new_data.append(copyto(i))
if self._next_idx >= len(self._storage):
self._storage.append(data)
#print self._storage
else:
self._storage[self._next_idx] = data
self._next_idx = (self._next_idx + 1) % self._maxsize
idx = self._next_idx
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):
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=0.4):
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)
#print self._it_min.min(), weights
weights = np.array(weights)
weights /= np.sum(weights)
ret = []
for i in xrange(batch_size):
ret.append(self._storage[idxes[i]])
return (ret, idxes, weights)
def update_priorities(self, idxes, priorities):
assert len(idxes) == len(priorities)
#print priorities, np.sum(priorities)
for idx, priority in zip(idxes, priorities):
#print priority
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 PrioritizedReplayBuffer(ReplayBuffer):
def __init__(self, buffer_size, input_dim, batch_size, alpha):
super(PrioritizedReplayBuffer, self).__init__(buffer_size, input_dim,
batch_size)
# For PER. Parameter settings.
self.max_priority, self.tree_ptr = 1.0, 0
self.alpha = alpha
tree_capacity = 1
while tree_capacity < self.buffer_size:
tree_capacity *= 2
self.sum_tree = SumSegmentTree(tree_capacity)
self.min_tree = MinSegmentTree(tree_capacity)
def store(self, state: np.ndarray, action: int, reward: float,
next_state: np.ndarray, done: int):
super().store(state, action, reward, next_state, done)
self.sum_tree[self.tree_ptr] = self.max_priority**self.alpha
self.min_tree[self.tree_ptr] = self.max_priority**self.alpha
self.tree_ptr = (self.tree_ptr + 1) % self.buffer_size
def batch_load(self, beta):
# indices를 받아오는 부분은 병렬처리!!, 그리고 같은 함수에서 weight도 받을 수 있다.
indices = self._sample_proportional_indices()
weights = np.array(
[self._calculate_weight(idx, beta) for idx in indices])
return dict(states=self.state_buffer[indices],
actions=self.action_buffer[indices],
rewards=self.reward_buffer[indices],
next_states=self.next_state_buffer[indices],
dones=self.done_buffer[indices],
weights=weights,
indices=indices)
def update_priorities(self, indices, priorities):
# 이 부분도 병렬 처리 할 수 있는 구간.
for idx, priority in zip(indices, priorities):
self.sum_tree[idx] = priority**self.alpha
self.min_tree[idx] = priority**self.alpha
self.max_priority = max(self.max_priority, priority)
def _sample_proportional_indices(self):
indices = []
p_total = self.sum_tree.sum(0, len(self) - 1)
segment = p_total / self.batch_size
# multiprocessing 등을 활용해서 병렬처리 하자
for i in range(self.batch_size):
a = segment * i
b = segment * (i + 1)
sample = np.random.uniform(a, b)
idx = self.sum_tree.retrieve(sample) # sample의 tree에서의 idx를 리턴
indices.append(idx)
return indices
def _calculate_weight(self, idx, beta):
# 이 부분은 batch 당 weight 구할 때 한번만 하면 될듯.
p_min = self.min_tree.min() / self.sum_tree.sum()
max_weight = (p_min * len(self))**(-beta)
p_sample = self.sum_tree[idx] / self.sum_tree.sum()
weight = (p_sample * len(self))**(-beta)
weight /= max_weight
return weight
class ReplayBuffer:
"""Fixed-size buffer to store experience tuples."""
def __init__(self, action_size, buffer_size, batch_size, alpha):
"""Initialize a ReplayBuffer object.
Params
======
action_size (int): dimension of each action
buffer_size (int): maximum size of buffer
batch_size (int): size of each training batch
alpha (float): alpha PER value
"""
self.max_priority = 1.0
self.alpha = alpha
# capacity must be positive and a power of 2.
self.tree_capacity = 1
while self.tree_capacity < buffer_size:
self.tree_capacity *= 2
self.sum_tree = SumSegmentTree(self.tree_capacity)
self.min_tree = MinSegmentTree(self.tree_capacity)
self.action_size = action_size
self.memory = []
self.batch_size = batch_size
self.experience = namedtuple(
"Experience",
field_names=["state", "action", "reward", "next_state", "done"])
def add(self, t, state, action, reward, next_state, done):
"""Add a new experience to memory."""
e = self.experience(state, action, reward, next_state, done)
idx = t % self.tree_capacity
if t >= self.tree_capacity:
self.memory[idx] = e
else:
self.memory.append(e)
# insert experience index in priority tree
self.sum_tree[idx] = self.max_priority**self.alpha
self.min_tree[idx] = self.max_priority**self.alpha
def sample(self, beta):
"""Sampling a batch of relevant experiences from memory."""
indices = self.relevant_sample_indx()
idxs = np.vstack(indices).astype(np.int)
states = torch.from_numpy(
np.vstack([self.memory[i].state
for i in indices])).float().to(device)
actions = torch.from_numpy(
np.vstack([self.memory[i].action
for i in indices])).long().to(device)
rewards = torch.from_numpy(
np.vstack([self.memory[i].reward
for i in indices])).float().to(device)
next_states = torch.from_numpy(
np.vstack([self.memory[i].next_state
for i in indices])).float().to(device)
dones = torch.from_numpy(
np.vstack([self.memory[i].done
for i in indices]).astype(np.uint8)).float().to(device)
weights = torch.from_numpy(
np.array([self.isw(i, beta) for i in indices])).float().to(device)
return (idxs, states, actions, rewards, next_states, dones, weights)
def relevant_sample_indx(self):
"""Selecting most informative sample indices."""
indices = []
p_total = self.sum_tree.sum(0, len(self) - 1)
segment = p_total / self.batch_size
for i in range(self.batch_size):
a = segment * i
b = segment * (i + 1)
upperbound = random.uniform(a, b)
idx = self.sum_tree.retrieve(upperbound)
indices.append(idx)
return indices
def update_priorities(self, indices, priorities):
"""Update priorities of sampled transitions."""
assert indices.shape[0] == priorities.shape[0]
for idx, priority in zip(indices.flatten(), priorities.flatten()):
assert priority > 0
assert 0 <= idx < len(self)
self.sum_tree[idx] = priority**self.alpha
self.min_tree[idx] = priority**self.alpha
self.max_priority = max(self.max_priority, priority)
def isw(self, idx, beta):
"""Compute Importance Sample Weight."""
# get max weight
p_min = self.min_tree.min() / self.sum_tree.sum()
max_weight = (p_min * len(self))**(-beta)
# calculate weights
p_sample = self.sum_tree[idx] / self.sum_tree.sum()
weight = (p_sample * len(self))**(-beta)
is_weight = weight / max_weight
return is_weight
def __len__(self):
"""Return the current size of internal memory."""
return len(self.memory)
class PrioritizedReplayBuffer(object):
def __init__(self, size, alpha=0.6):
"""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)
self._storage = []
self._maxsize = size
self._next_idx = 0
assert alpha >= 0
self._alpha = alpha
self.it_capacity = 1
while self.it_capacity < size * 2: # We use double the soft capacity of the PER for the segment trees to allow for any overflow over the soft capacity limit before samples are removed
self.it_capacity *= 2
self._it_sum = SumSegmentTree(self.it_capacity)
self._it_min = MinSegmentTree(self.it_capacity)
self._max_priority = 1.0
def _add(self, obs_t, action, reward, obs_tp1, done): # self, state, policy_output, reward, last_state, done
data = (obs_t, action, reward, obs_tp1, done)
if self._next_idx >= len(self._storage):
self._storage.append(data)
else:
self._storage[self._next_idx] = data
self._next_idx = (self._next_idx + 1) % self._maxsize
def _remove(self, num_samples):
del self._storage[:num_samples]
self._next_idx = len(self._storage)
def _encode_sample(self, idxes):
obses_t, actions, rewards, obses_tp1, dones = [], [], [], [], []
for i in idxes:
data = self._storage[i]
obs_t, action, reward, obs_tp1, done = data
obses_t.append(np.array(obs_t, copy=False))
actions.append(action)
rewards.append(reward)
obses_tp1.append(np.array(obs_tp1, copy=False))
dones.append(done)
return [np.array(obses_t), actions, np.array(rewards),\
np.array(obses_tp1), np.array(dones)]
def add(self, state, policy_output, reward, last_state, done): # self, state, policy_output, reward, last_state, done
idx = self._next_idx
#assert idx < self.it_capacity, "Number of samples in replay memory exceeds capacity of segment trees. Please increase capacity of segment trees or increase the frequency at which samples are removed from the replay memory"
self._add(state, policy_output, reward, last_state, done)
self._it_sum[idx] = self._max_priority ** self._alpha
self._it_min[idx] = self._max_priority ** self._alpha
def remove(self, num_samples):
self._remove(num_samples)
self._it_sum.remove_items(num_samples)
self._it_min.remove_items(num_samples)
def _sample_proportional(self, batch_size):
res = []
p_total = self._it_sum.sum(0, len(self._storage) - 1)
every_range_len = p_total / batch_size
for i in range(batch_size):
mass = random.random() * every_range_len + i * every_range_len
idx = self._it_sum.find_prefixsum_idx(mass)
res.append(idx)
return res
def miniBatch(self, batch_size, beta=0.4, epsilon=1e-8):
"""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
rew_batch: np.array
rewards received as results of executing act_batch
next_obs_batch: np.array
next set of observations seen after executing act_batch
done_mask: np.array
done_mask[i] = 1 if executing act_batch[i] resulted in
the end of an episode and 0 otherwise.
gammas: np.array
product of gammas for N-step returns
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
"""
assert beta > 0
idxes = self._sample_proportional(batch_size)
weights = []
p_min = self._it_min.min() / (self._it_sum.sum() + epsilon)
max_weight = (p_min * len(self._storage)) ** (-beta)
for idx in idxes:
p_sample = self._it_sum[idx] / (self._it_sum.sum() + epsilon)
weight = (p_sample * len(self._storage)) ** (-beta)
weights.append(weight / (max_weight + epsilon))
weights = np.array(weights)
encoded_sample = self._encode_sample(idxes)
return encoded_sample, idxes, weights
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):
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)
def get_size(self):
return len(self._storage)
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 = []
p_total = self._it_sum.sum(0, len(self._storage) - 1)
every_range_len = p_total / batch_size
for i in range(batch_size):
mass = random.random() * every_range_len + i * every_range_len
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
rew_batch: np.array
rewards received as results of executing act_batch
next_obs_batch: np.array
next set of observations seen after executing act_batch
done_mask: np.array
done_mask[i] = 1 if executing act_batch[i] resulted in
the end of an episode and 0 otherwise.
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
"""
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].
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):
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 PrioritizedReplayMemory(object):
def __init__(self,
capacity=100000,
priority_fraction=0.0,
discount_gamma_game_reward=1.0,
discount_gamma_graph_reward=1.0,
discount_gamma_count_reward=1.0,
accumulate_reward_from_final=False):
# prioritized replay memory
self._storage = []
self.capacity = capacity
self._next_idx = 0
assert priority_fraction >= 0
self._alpha = priority_fraction
it_capacity = 1
while it_capacity < capacity:
it_capacity *= 2
self._it_sum = SumSegmentTree(it_capacity)
self._it_min = MinSegmentTree(it_capacity)
self._max_priority = 1.0
self.discount_gamma_game_reward = discount_gamma_game_reward
self.discount_gamma_graph_reward = discount_gamma_graph_reward
self.discount_gamma_count_reward = discount_gamma_count_reward
self.accumulate_reward_from_final = accumulate_reward_from_final
def __len__(self):
return len(self._storage)
@property
def storage(self):
"""[(np.ndarray, float, float, np.ndarray, bool)]: content of the replay buffer"""
return self._storage
@property
def buffer_size(self):
"""float: Max capacity of the buffer"""
return self.capacity
def can_sample(self, n_samples):
"""
Check if n_samples samples can be sampled
from the buffer.
:param n_samples: (int)
:return: (bool)
"""
return len(self) >= n_samples
def is_full(self):
"""
Check whether the replay buffer is full or not.
:return: (bool)
"""
return len(self) == self.buffer_size
def add(self, *args):
"""
add a new transition to the buffer
"""
idx = self._next_idx
data = Transition(*args)
if self._next_idx >= len(self._storage):
self._storage.append(data)
else:
self._storage[self._next_idx] = data
self._next_idx = (self._next_idx + 1) % self.capacity
self._it_sum[idx] = self._max_priority**self._alpha
self._it_min[idx] = self._max_priority**self._alpha
def get_next_final_pos(self, which_memory, head):
i = head
while True:
if i >= len(self._storage):
return None
if self._storage[i].is_final:
return i
i += 1
return None
def _get_single_transition(self, idx, n):
assert n > 0
head = idx
# if n is 1, then head can't be is_final
if n == 1:
if self._storage[head].is_final:
return None
# if n > 1, then all except tail can't be is_final
else:
if np.any([item.is_final
for item in self._storage[head:head + n]]):
return None
next_final = self.get_next_final_pos(self._storage, head)
if next_final is None:
return None
# all good
obs = self._storage[head].observation_list
prev_action = self._storage[head].prev_action_list
candidate = self._storage[head].action_candidate_list
chosen_indices = self._storage[head].chosen_indices
graph_triplets = self._storage[head].graph_triplets
next_obs = self._storage[head + n].observation_list
next_prev_action = self._storage[head + n].prev_action_list
next_candidate = self._storage[head + n].action_candidate_list
next_graph_triplets = self._storage[head + n].graph_triplets
tmp = next_final - head + 1 if self.accumulate_reward_from_final else n + 1
rewards_up_to_next_final = [
self.discount_gamma_game_reward**i * self._storage[head + i].reward
for i in range(tmp)
]
reward = torch.sum(torch.stack(rewards_up_to_next_final))
graph_rewards_up_to_next_final = [
self.discount_gamma_graph_reward**i *
self._storage[head + i].graph_reward for i in range(tmp)
]
graph_reward = torch.sum(torch.stack(graph_rewards_up_to_next_final))
count_rewards_up_to_next_final = [
self.discount_gamma_count_reward**i *
self._storage[head + i].count_reward for i in range(tmp)
]
count_reward = torch.sum(torch.stack(count_rewards_up_to_next_final))
return (obs, prev_action, candidate, chosen_indices, graph_triplets,
reward + graph_reward + count_reward, next_obs,
next_prev_action, next_candidate, next_graph_triplets)
def _encode_sample(self, idxes, ns):
actual_indices, actual_ns = [], []
obs, prev_action, candidate, chosen_indices, graph_triplets, reward, next_obs, next_prev_action, next_candidate, next_graph_triplets = [], [], [], [], [], [], [], [], [], []
for i, n in zip(idxes, ns):
t = self._get_single_transition(i, n)
if t is None:
continue
actual_indices.append(i)
actual_ns.append(n)
obs.append(t[0])
prev_action.append(t[1])
candidate.append(t[2])
chosen_indices.append(t[3])
graph_triplets.append(t[4])
reward.append(t[5])
next_obs.append(t[6])
next_prev_action.append(t[7])
next_candidate.append(t[8])
next_graph_triplets.append(t[9])
if len(actual_indices) == 0:
return None
chosen_indices = np.array(chosen_indices) # batch
reward = torch.stack(reward, 0) # batch
actual_ns = np.array(actual_ns)
return [
obs, prev_action, candidate, chosen_indices, graph_triplets,
reward, next_obs, next_prev_action, next_candidate,
next_graph_triplets, actual_indices, actual_ns
]
def sample(self, batch_size, beta=0, multi_step=1):
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)
# sample n
ns = np.random.randint(1, multi_step + 1, size=batch_size)
encoded_sample = self._encode_sample(idxes, ns)
if encoded_sample is None:
return None
actual_indices = encoded_sample[-2]
for idx in actual_indices:
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)
return encoded_sample + [weights]
def _get_single_sequence_transition(self, idx, sample_history_length):
assert sample_history_length > 0
head = idx
# if n is 1, then head can't be is_final
if sample_history_length == 1:
if self._storage[head].is_final:
return None
# if n > 1, then all except tail can't be is_final
else:
if np.any([
item.is_final
for item in self._storage[head:head +
sample_history_length]
]):
return None
next_final = self.get_next_final_pos(self._storage, head)
if next_final is None:
return None
# all good
res = []
for m in range(sample_history_length):
obs = self._storage[head + m].observation_list
candidate = self._storage[head + m].action_candidate_list
chosen_indices = self._storage[head + m].chosen_indices
graph_triplets = self._storage[head + m].graph_triplets
next_obs = self._storage[head + m + 1].observation_list
next_candidate = self._storage[head + m + 1].action_candidate_list
next_graph_triplets = self._storage[head + m + 1].graph_triplets
tmp = next_final - (
head + m) + 1 if self.accumulate_reward_from_final else 1
rewards_up_to_next_final = [
self.discount_gamma_game_reward**i *
self._storage[head + m + i].reward for i in range(tmp)
]
reward = torch.sum(torch.stack(rewards_up_to_next_final))
graph_rewards_up_to_next_final = [
self.discount_gamma_graph_reward**i *
self._storage[head + m + i].graph_reward for i in range(tmp)
]
graph_reward = torch.sum(
torch.stack(graph_rewards_up_to_next_final))
count_rewards_up_to_next_final = [
self.discount_gamma_count_reward**i *
self._storage[head + m + i].count_reward for i in range(tmp)
]
count_reward = torch.sum(
torch.stack(count_rewards_up_to_next_final))
res.append([
obs, candidate, chosen_indices, graph_triplets,
reward + graph_reward + count_reward, next_obs, next_candidate,
next_graph_triplets
])
return res
def _encode_sample_sequence(self, idxes, sample_history_length):
assert sample_history_length > 0
res = []
for _ in range(sample_history_length):
tmp = []
for i in range(8):
tmp.append([])
res.append(tmp)
actual_indices = []
# obs, candidate, chosen_indices, graph_triplets, reward, next_obs, next_candidate, next_graph_triplets
for i in idxes:
t = self._get_single_sequence_transition(i, sample_history_length)
if t is None:
continue
actual_indices.append(i)
for step in range(sample_history_length):
t_s = t[step]
res[step][0].append(t_s[0])
res[step][1].append(t_s[1])
res[step][2].append(t_s[2])
res[step][3].append(t_s[3])
res[step][4].append(t_s[4])
res[step][5].append(t_s[5])
res[step][6].append(t_s[6])
res[step][7].append(t_s[7])
if len(actual_indices) == 0:
return None
for i in range(sample_history_length):
res[i][2] = np.array(res[i][2]) # batch
res[i][4] = torch.stack(res[i][4], 0) # batch
return res + [actual_indices]
def sample_sequence(self, batch_size, beta=0, sample_history_length=1):
assert beta > 0
idxes = self._sample_proportional(batch_size)
res_weights = []
p_min = self._it_min.min() / self._it_sum.sum()
max_weight = (p_min * len(self._storage))**(-beta)
encoded_sample = self._encode_sample_sequence(idxes,
sample_history_length)
if encoded_sample is None:
return None
actual_indices = encoded_sample[-1]
for _h in range(sample_history_length):
tmp_weights = []
for idx in actual_indices:
p_sample = self._it_sum[idx + _h] / self._it_sum.sum()
weight = (p_sample * len(self._storage))**(-beta)
tmp_weights.append(weight / max_weight)
tmp_weights = np.array(tmp_weights)
res_weights.append(tmp_weights)
return encoded_sample + [res_weights]
def _sample_proportional(self, batch_size):
res = []
for _ in range(batch_size):
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 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):
if 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)
else:
print("something wrong with priority: ", str(priority))
return False
return True
def avg_rewards(self):
if len(self._storage) == 0:
return 0.0
rewards = [self._storage[i].reward for i in range(len(self._storage))]
return to_np(torch.mean(torch.stack(rewards)))
class PrioritizedReplayBuffer(ReplayBuffer):
"""Prioritized Replay buffer.
Attributes:
max_priority (float): max priority
tree_ptr (int): next index of tree
alpha (float): alpha parameter for prioritized replay buffer
sum_tree (SumSegmentTree): sum tree for prior
min_tree (MinSegmentTree): min tree for min prior to get max weight
"""
def __init__(
self,
obs_dim: int,
size: int,
batch_size: int = 32,
alpha: float = 0.6,
n_step: int = 1,
gamma: float = 0.99,
):
"""Initialization."""
assert alpha >= 0
super(PrioritizedReplayBuffer,
self).__init__(obs_dim, size, batch_size, n_step, gamma)
self.max_priority, self.tree_ptr = 1.0, 0
self.alpha = alpha
# capacity must be positive and a power of 2.
tree_capacity = 1
while tree_capacity < self.max_size:
tree_capacity *= 2
self.sum_tree = SumSegmentTree(tree_capacity)
self.min_tree = MinSegmentTree(tree_capacity)
def store(
self,
obs: np.ndarray,
act: int,
rew: float,
next_obs: np.ndarray,
done: bool,
) -> Tuple[np.ndarray, np.ndarray, float, np.ndarray, bool]:
"""Store experience and priority."""
transition = super().store(obs, act, rew, next_obs, done)
if transition:
self.sum_tree[self.tree_ptr] = self.max_priority**self.alpha
self.min_tree[self.tree_ptr] = self.max_priority**self.alpha
self.tree_ptr = (self.tree_ptr + 1) % self.max_size
return transition
def sample_batch(self, beta: float = 0.4) -> Dict[str, np.ndarray]:
"""Sample a batch of experiences."""
assert len(self) >= self.batch_size
assert beta > 0
indices = self._sample_proportional()
obs = self.obs_buf[indices]
next_obs = self.next_obs_buf[indices]
acts = self.acts_buf[indices]
rews = self.rews_buf[indices]
done = self.done_buf[indices]
weights = np.array([self._calculate_weight(i, beta) for i in indices])
return dict(
obs=obs,
next_obs=next_obs,
acts=acts,
rews=rews,
done=done,
weights=weights,
indices=indices,
)
def update_priorities(self, indices: List[int], priorities: np.ndarray):
"""Update priorities of sampled transitions."""
assert len(indices) == len(priorities)
for idx, priority in zip(indices, priorities):
assert priority > 0
assert 0 <= idx < len(self)
self.sum_tree[idx] = priority**self.alpha
self.min_tree[idx] = priority**self.alpha
self.max_priority = max(self.max_priority, priority)
def _sample_proportional(self) -> List[int]:
"""Sample indices based on proportions."""
indices = []
p_total = self.sum_tree.sum(0, len(self) - 1)
segment = p_total / self.batch_size
for i in range(self.batch_size):
a = segment * i
b = segment * (i + 1)
upperbound = random.uniform(a, b)
idx = self.sum_tree.retrieve(upperbound)
indices.append(idx)
return indices
def _calculate_weight(self, idx: int, beta: float):
"""Calculate the weight of the experience at idx."""
# get max weight
p_min = self.min_tree.min() / self.sum_tree.sum()
max_weight = (p_min * len(self))**(-beta)
# calculate weights
p_sample = self.sum_tree[idx] / self.sum_tree.sum()
weight = (p_sample * len(self))**(-beta)
weight = weight / max_weight
return weight
class PrioritizedReplayBuffer(ReplayBuffer):
"""
Adapt from https://github.com/hill-a/stable-baselines/blob/master/stable_baselines/common/buffers.py
"""
def __init__(self, obs_space, action_space, capacity, exponent, device, optimize_memory_usage=False):
super().__init__(obs_space, action_space, capacity, device,
optimize_memory_usage=optimize_memory_usage)
assert exponent >= 0
self.exponent = exponent
it_capacity = 1
while it_capacity < self.capacity:
it_capacity *= 2
self._it_sum = SumSegmentTree(it_capacity)
self._it_min = MinSegmentTree(it_capacity)
self._max_priority = 1.0
def _sample_proportional(self, batch_size):
total = self._it_sum.sum(0, len(self) - 1)
mass = np.random.random(size=batch_size) * total
idx = self._it_sum.find_prefixsum_idx(mass)
# replace idx == self.idx
if self.full and self.optimize_memory_usage:
while np.any(idx == self.idx):
replace_mass = np.random.random(len(idx == self.idx)) * total
replace_idx = self._it_sum.find_prefixsum_idx(replace_mass)
idx[idx == self.idx] = replace_idx
return idx
def add(self, obs, action, reward, next_obs, done):
idx = self.idx
super().add(obs, action, reward, next_obs, done)
self._it_sum[idx] = self._max_priority ** self.exponent
self._it_min[idx] = self._max_priority ** self.exponent
def sample(self, batch_size, beta=0):
assert beta >= 0
idxes = self._sample_proportional(batch_size)
p_min = self._it_min.min() / self._it_sum.sum()
max_weight = (p_min * len(self)) ** (-beta)
p_sample = self._it_sum[idxes] / self._it_sum.sum()
weights = (p_sample * len(self)) ** (-beta) / max_weight
obses, actions, rewards, next_obses, not_dones = self._sample(idxes)
priority_kwargs = {
'weights': weights,
'idxes': idxes
}
return obses, actions, rewards, next_obses, not_dones, priority_kwargs
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)
self._it_sum[idxes] = priorities ** self.exponent
self._it_min[idxes] = priorities ** self.exponent
self._max_priority = max(self._max_priority, np.max(priorities))
