Metadata-Version: 2.5
Name: memmap-replay-buffer
Version: 0.2.0
Summary: Simple Replay Buffer for RL
Project-URL: Homepage, https://pypi.org/project/memmap-replay-buffer/
Project-URL: Repository, https://codeberg.org/lucidrains/memmap-replay-buffer
Author-email: Phil Wang <lucidrains@gmail.com>
License: MIT License
        
        Copyright (c) 2025 Phil Wang
        
        Permission is hereby granted, free of charge, to any person obtaining a copy
        of this software and associated documentation files (the "Software"), to deal
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        THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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        SOFTWARE.
License-File: LICENSE
Keywords: artificial intelligence,deep learning,replay buffer
Classifier: Development Status :: 4 - Beta
Classifier: Intended Audience :: Developers
Classifier: License :: OSI Approved :: MIT License
Classifier: Topic :: Scientific/Engineering :: Artificial Intelligence
Requires-Python: >=3.10
Requires-Dist: beartype
Requires-Dist: einops>=0.8.1
Requires-Dist: einx>=0.4.0
Requires-Dist: numpy
Requires-Dist: torch>=2.4
Provides-Extra: test
Requires-Dist: h5py; extra == 'test'
Requires-Dist: pytest; extra == 'test'
Description-Content-Type: text/markdown

## memmap-replay-buffer

An easy-to-use numpy memmap replay buffer for RL and other sequence-based learning tasks.

## Install

```bash
$ pip install memmap-replay-buffer
```

## Usage

Supports trajectory-level, timestep-level, and n-step transition dataloading from a single stored buffer.

```python
import torch
from memmap_replay_buffer import ReplayBuffer

# initialize buffer

buffer = ReplayBuffer(
    './replay_data',
    max_episodes = 1000,
    max_timesteps = 500,
    fields = dict(
        state = ('float', (3, 16, 16), 0.),    # type, shape, and optional default value
        action = ('int', 2),
        reward = 'float'                       # default shape is ()
    ),
    meta_fields = dict(
        task_id = 'int'
    ),
    circular = True,
    overwrite = True
)

# store 4 episodes

for _ in range(4):
    with buffer.one_episode(task_id = 1):
        for _ in range(100):
            buffer.store(
                state = torch.randn(3, 16, 16),
                action = torch.randint(0, 4, (2,)).numpy(),
                reward = 1.0
            )

# rehydrate from disk

buffer_rehydrated = ReplayBuffer.from_folder('./replay_data')
assert buffer_rehydrated.num_episodes == 4
```

### Trajectory-level

Variable-length trajectories, automatically padded with mask and lengths.

```python
dataloader = buffer.dataloader(
    batch_size = 2,
    return_mask = True,
    to_named_tuple = ('state', 'action', 'reward', 'task_id', '_mask', '_lens')
)

for state, action, reward, task_id, mask, lens in dataloader:
    assert state.shape   == (2, 100, 3, 16, 16)
    assert action.shape  == (2, 100, 2)
    assert reward.shape  == (2, 100)
    assert task_id.shape == (2,)

    assert lens.shape    == (2,)
    assert mask.shape    == (2, 100)
```

### Timestep-level

Individual timesteps across episodes, with optional `filter_meta` for conditioning.

```python
dataloader = buffer.dataloader(
    batch_size = 8,
    filter_meta = dict(
        task_id = 1
    ),
    to_named_tuple = ('state', 'action', 'task_id'),
    timestep_level = True,
    drop_last = True
)

for state, action, task_id in dataloader:
    assert state.shape   == (8, 3, 16, 16)
    assert action.shape  == (8, 2)
    assert task_id.shape == (8,)
```

### N-step transitions

Fetches `current_fields` at $t$, `next_fields` at $t + n$ (prefixed `next_`), and `sequence_fields` from $t$ to $t + n$ (prefixed `seq_`, zero-padded at episode boundaries). Use `fieldname_map` to remap to your model's kwargs.

```python
dataloader = buffer.dataloader(
    batch_size = 4,
    n_steps = 5,
    current_fields = ('state',),
    next_fields = ('state',),
    sequence_fields = ('action', 'reward'),
    to_named_tuple = ('state', 'next_state', 'action_chunk', 'rewards', 'n_step_lens'),
    fieldname_map = {
        'seq_action': 'action_chunk',
        'seq_reward': 'rewards'
    }
)

for state, next_state, action_chunk, rewards, n_step_lens in dataloader:
    assert state.shape == (4, 3, 16, 16)
    assert next_state.shape == (4, 3, 16, 16)
    assert action_chunk.shape == (4, 5, 2)
    assert rewards.shape == (4, 5)
    assert n_step_lens.shape == (4,)
```

### Storing whole episodes

`store_episode` takes one tensor per field, all sharing the same time dimension (meta fields are scalars or per-episode shapes).

```python
buffer.store_episode(
    state = torch.randn(100, 3, 16, 16),
    action = torch.randint(0, 4, (100, 2)),
    reward = torch.randn(100),
    task_id = 1
)
```

### Batched parallel collection

When collecting from multiple parallel environments, `batched_episode` + `store_batch` keeps every environment at the same timestep. `create_collector` additionally accumulates group-batched data and stores finished episodes for you.

```python
with buffer.batched_episode(batch_size = 4, task_id = [0, 1, 2, 3]):
    for t in range(100):
        buffer.store_batch(
            state = states,     # (4, 3, 16, 16)
            action = actions    # (4, 2)
        )
```

### Updating data in place

`update` overwrites already-stored episodes, e.g. for bootstrapped returns or value targets.

```python
buffer.update(returns = torch.randn(3, 100))            # all populated episodes
buffer.update(episode_ids, returns = returns_for_ids)   # specific episodes
buffer.update(0, returns = returns_for_one)             # scalar index
```

### Pulling everything at once

```python
all_data = buffer.get_all_data()  # dict of tensors, time-padded to the longest episode
```

### Reopening, read-only, and clearing

`overwrite = False` (or `from_folder`) rehydrates an existing buffer from disk; the stored config is validated against the requested one, so mismatched `fields`/`max_episodes` raise a clear error. `read_only = True` guarantees no files are created or written. `clear()` wipes all episodes.

```python
buffer = ReplayBuffer.from_folder('./replay_data', read_only = True)
buffer = ReplayBuffer('./replay_data', max_episodes = 1000, max_timesteps = 500, fields = ..., overwrite = False)
buffer.clear()
```

### Concatenating buffers

`ConcatReplayBuffer` combines several (read-only) buffers of identical fields into one dataset.

```python
from memmap_replay_buffer import ConcatReplayBuffer

concat = ConcatReplayBuffer(['./replay_data_a', './replay_data_b'])
dataloader = concat.dataloader(batch_size = 2, return_mask = True)
```

### Notes

- `circular = True` overwrites the oldest episodes once the buffer is full; `circular = False` raises when full.
- Fields missing from `store` are filled with their declared default value (or zeros).
- `flush_every_store_step` controls how often the memmaps are flushed to disk while storing (default 1; raise it for faster collection at the cost of durability).
- `ReplayBufferH5PY` (`pip install h5py`) is an HDF5-backed variant with the same interface, optionally gzip-compressed.
