wehub-resource-sync
111 lines
3.4 KiB
Python
111 lines
3.4 KiB
Python
from typing import Any, Dict, Optional
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import numpy as np
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from ray.rllib.policy.sample_batch import MultiAgentBatch
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from ray.rllib.utils.annotations import override
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from ray.rllib.utils.replay_buffers.replay_buffer import ReplayBuffer, StorageUnit
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from ray.rllib.utils.typing import SampleBatchType
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from ray.util.annotations import DeveloperAPI
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@DeveloperAPI
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class FifoReplayBuffer(ReplayBuffer):
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"""This replay buffer implements a FIFO queue.
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Sometimes, e.g. for offline use cases, it may be desirable to use
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off-policy algorithms without a Replay Buffer.
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This FifoReplayBuffer can be used in-place to achieve the same effect
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without having to introduce separate algorithm execution branches.
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For simplicity and efficiency reasons, this replay buffer stores incoming
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sample batches as-is, and returns them one at time.
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This is to avoid any additional load when this replay buffer is used.
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"""
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def __init__(self, *args, **kwargs):
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"""Initializes a FifoReplayBuffer.
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Args:
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``*args`` : Forward compatibility args.
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``**kwargs``: Forward compatibility kwargs.
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"""
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# Completely by-passing underlying ReplayBuffer by setting its
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# capacity to 1 (lowest allowed capacity).
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ReplayBuffer.__init__(self, 1, StorageUnit.FRAGMENTS, **kwargs)
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self._queue = []
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@DeveloperAPI
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@override(ReplayBuffer)
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def add(self, batch: SampleBatchType, **kwargs) -> None:
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return self._queue.append(batch)
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@DeveloperAPI
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@override(ReplayBuffer)
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def sample(self, *args, **kwargs) -> Optional[SampleBatchType]:
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"""Sample a saved training batch from this buffer.
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Args:
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``*args`` : Forward compatibility args.
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``**kwargs``: Forward compatibility kwargs.
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Returns:
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A single training batch from the queue.
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"""
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if len(self._queue) <= 0:
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# Return empty SampleBatch if queue is empty.
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return MultiAgentBatch({}, 0)
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batch = self._queue.pop(0)
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# Equal weights of 1.0.
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batch["weights"] = np.ones(len(batch))
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return batch
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@DeveloperAPI
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def update_priorities(self, *args, **kwargs) -> None:
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"""Update priorities of items at given indices.
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No-op for this replay buffer.
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Args:
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``*args`` : Forward compatibility args.
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``**kwargs``: Forward compatibility kwargs.
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"""
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pass
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@DeveloperAPI
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@override(ReplayBuffer)
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def stats(self, debug: bool = False) -> Dict:
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"""Returns the stats of this buffer.
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Args:
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debug: If true, adds sample eviction statistics to the returned stats dict.
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Returns:
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A dictionary of stats about this buffer.
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"""
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# As if this replay buffer has never existed.
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return {}
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@DeveloperAPI
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@override(ReplayBuffer)
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def get_state(self) -> Dict[str, Any]:
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"""Returns all local state.
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Returns:
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The serializable local state.
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"""
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# Pass through replay buffer does not save states.
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return {}
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@DeveloperAPI
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@override(ReplayBuffer)
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def set_state(self, state: Dict[str, Any]) -> None:
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"""Restores all local state to the provided `state`.
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Args:
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state: The new state to set this buffer. Can be obtained by calling
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`self.get_state()`.
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"""
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pass
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