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
self._prio_change_stats = WindowStat("reprio", 1000)
def add(self, obs_t, action, reward, obs_tp1, done, weight):
"""See ReplayBuffer.store_effect"""
idx = self._next_idx
super(PrioritizedReplayBuffer, self).add(obs_t, action, reward,
obs_tp1, done, weight)
if weight is None:
weight = self._max_priority
self._it_sum[idx] = weight**self._alpha
self._it_min[idx] = weight**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))
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
self._num_sampled += batch_size
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)
delta = priority**self._alpha - self._it_sum[idx]
self._prio_change_stats.push(delta)
self._it_sum[idx] = priority**self._alpha
self._it_min[idx] = priority**self._alpha
self._max_priority = max(self._max_priority, priority)
def stats(self, debug=False):
parent = ReplayBuffer.stats(self, debug)
if debug:
parent.update(self._prio_change_stats.stats())
return parent
def test_max_interval_tree():
tree = MinSegmentTree(4)
tree[0] = 1.0
tree[2] = 0.5
tree[3] = 3.0
assert np.isclose(tree.min(), 0.5)
assert np.isclose(tree.min(0, 2), 1.0)
assert np.isclose(tree.min(0, 3), 0.5)
assert np.isclose(tree.min(0, -1), 0.5)
assert np.isclose(tree.min(2, 4), 0.5)
assert np.isclose(tree.min(3, 4), 3.0)
tree[2] = 0.7
assert np.isclose(tree.min(), 0.7)
assert np.isclose(tree.min(0, 2), 1.0)
assert np.isclose(tree.min(0, 3), 0.7)
assert np.isclose(tree.min(0, -1), 0.7)
assert np.isclose(tree.min(2, 4), 0.7)
assert np.isclose(tree.min(3, 4), 3.0)
tree[2] = 4.0
assert np.isclose(tree.min(), 1.0)
assert np.isclose(tree.min(0, 2), 1.0)
assert np.isclose(tree.min(0, 3), 1.0)
assert np.isclose(tree.min(0, -1), 1.0)
assert np.isclose(tree.min(2, 4), 3.0)
assert np.isclose(tree.min(2, 3), 4.0)
assert np.isclose(tree.min(2, -1), 4.0)
assert np.isclose(tree.min(3, 4), 3.0)
def test_max_interval_tree(self):
tree = MinSegmentTree(4)
tree[0] = 1.0
tree[2] = 0.5
tree[3] = 3.0
assert np.isclose(tree.min(), 0.5)
assert np.isclose(tree.min(0, 2), 1.0)
assert np.isclose(tree.min(0, 3), 0.5)
assert np.isclose(tree.min(0, -1), 0.5)
assert np.isclose(tree.min(2, 4), 0.5)
assert np.isclose(tree.min(3, 4), 3.0)
tree[2] = 0.7
assert np.isclose(tree.min(), 0.7)
assert np.isclose(tree.min(0, 2), 1.0)
assert np.isclose(tree.min(0, 3), 0.7)
assert np.isclose(tree.min(0, -1), 0.7)
assert np.isclose(tree.min(2, 4), 0.7)
assert np.isclose(tree.min(3, 4), 3.0)
tree[2] = 4.0
assert np.isclose(tree.min(), 1.0)
assert np.isclose(tree.min(0, 2), 1.0)
assert np.isclose(tree.min(0, 3), 1.0)
assert np.isclose(tree.min(0, -1), 1.0)
assert np.isclose(tree.min(2, 4), 3.0)
assert np.isclose(tree.min(2, 3), 4.0)
assert np.isclose(tree.min(2, -1), 4.0)
assert np.isclose(tree.min(3, 4), 3.0)
class PrioritizedReplayBuffer(ReplayBuffer):
@DeveloperAPI
def __init__(
self,
size,
alpha,
# added for dynamic experience replay
permanent_data_length=0,
human_data=None,
dynamic_experience_replay=False,
demonstration_zone_percentage=0):
"""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__
"""
# added for dynamic experience replay
super(PrioritizedReplayBuffer, self).__init__(size,
permanent_data_length)
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
self._prio_change_stats = WindowStat("reprio", 1000)
# added for dynamic experience replay
self._permanent_data_length = permanent_data_length
self._demo_index = permanent_data_length
if dynamic_experience_replay and demonstration_zone_percentage > 0:
self._max_demo_size = math.ceil(
size * demonstration_zone_percentage
) # assign the size for demonstration zone
assert self._max_demo_size > 10000, "demonstration zone is too small, please increase buffer size"
prGreen("the maximum demonstration zone size: {}".format(
self._max_demo_size))
if self._permanent_data_length > 0:
# insert human demos to the buffer with full prioritization
for transition in human_data:
self.add(transition[0], transition[1], transition[2],
transition[3], transition[4], 1)
@DeveloperAPI
def add(self, obs_t, action, reward, obs_tp1, done, weight):
"""See ReplayBuffer.store_effect"""
idx = self._next_idx
super(PrioritizedReplayBuffer, self).add(obs_t, action, reward,
obs_tp1, done, weight)
if weight is None:
weight = self._max_priority
self._it_sum[idx] = weight**self._alpha
self._it_min[idx] = weight**self._alpha
# added for dynamic experience replay
def update_demos(self, demo_data):
updated_demo_size = self._permanent_data_length + len(demo_data)
if updated_demo_size < self._max_demo_size:
self._permanent_data_length = updated_demo_size
else:
self._permanent_data_length = self._max_demo_size
for transition in demo_data:
self._storage[self._demo_index] = transition
self._demo_index = (self._demo_index + 1) % self._max_demo_size
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))
idx = self._it_sum.find_prefixsum_idx(mass)
res.append(idx)
return res
@DeveloperAPI
def sample_idxes(self, batch_size):
return self._sample_proportional(batch_size)
@DeveloperAPI
def sample_with_idxes(self, idxes, beta):
assert beta > 0
self._num_sampled += len(idxes)
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])
@DeveloperAPI
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
self._num_sampled += batch_size
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])
@DeveloperAPI
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)
delta = priority**self._alpha - self._it_sum[idx]
self._prio_change_stats.push(delta)
self._it_sum[idx] = priority**self._alpha
self._it_min[idx] = priority**self._alpha
self._max_priority = max(self._max_priority, priority)
@DeveloperAPI
def stats(self, debug=False):
parent = ReplayBuffer.stats(self, debug)
if debug:
parent.update(self._prio_change_stats.stats())
return parent