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.. automodule:: stable_baselines3.sac
SAC
===
`Soft Actor Critic (SAC) <https://spinningup.openai.com/en/latest/algorithms/sac.html>`_ Off-Policy Maximum Entropy Deep Reinforcement Learning with a Stochastic Actor.
SAC is the successor of `Soft Q-Learning SQL <https://arxiv.org/abs/1702.08165>`_ and incorporates the double Q-learning trick from TD3.
A key feature of SAC, and a major difference with common RL algorithms, is that it is trained to maximize a trade-off between expected return and entropy, a measure of randomness in the policy.
.. rubric:: Available Policies
.. autosummary::
:nosignatures:
MlpPolicy
CnnPolicy
Notes
-----
- Original paper: https://arxiv.org/abs/1801.01290
- OpenAI Spinning Guide for SAC: https://spinningup.openai.com/en/latest/algorithms/sac.html
- Original Implementation: https://github.com/haarnoja/sac
- Blog post on using SAC with real robots: https://bair.berkeley.edu/blog/2018/12/14/sac/
.. note::
In our implementation, we use an entropy coefficient (as in OpenAI Spinning or Facebook Horizon),
which is the equivalent to the inverse of reward scale in the original SAC paper.
The main reason is that it avoids having too high errors when updating the Q functions.
.. note::
The default policies for SAC differ a bit from others MlpPolicy: it uses ReLU instead of tanh activation,
to match the original paper
Can I use?
----------
- Recurrent policies: ❌
- Multi processing: ❌
- Gym spaces:
============= ====== ===========
Space Action Observation
============= ====== ===========
Discrete ❌ ✔️
Box ✔️ ✔️
MultiDiscrete ❌ ✔️
MultiBinary ❌ ✔️
============= ====== ===========
Example
-------
.. code-block:: python
import gym
import numpy as np
from stable_baselines3 import SAC
from stable_baselines3.sac import MlpPolicy
env = gym.make('Pendulum-v0')
model = SAC(MlpPolicy, env, verbose=1)
model.learn(total_timesteps=10000, log_interval=4)
model.save("sac_pendulum")
del model # remove to demonstrate saving and loading
model = SAC.load("sac_pendulum")
obs = env.reset()
while True:
action, _states = model.predict(obs, deterministic=True)
obs, reward, done, info = env.step(action)
env.render()
if done:
obs = env.reset()
Results
-------
PyBullet Environments
^^^^^^^^^^^^^^^^^^^^^
Results on the PyBullet benchmark (1M steps) using 3 seeds.
The complete learning curves are available in the `associated issue #48 <https://github.com/DLR-RM/stable-baselines3/issues/48>`_.
.. note::
Hyperparameters from the `gSDE paper <https://arxiv.org/abs/2005.05719>`_ were used (as they are tuned for PyBullet envs).
*Gaussian* means that the unstructured Gaussian noise is used for exploration,
*gSDE* (generalized State-Dependent Exploration) is used otherwise.
+--------------+--------------+--------------+--------------+
| Environments | SAC | SAC | TD3 |
+==============+==============+==============+==============+
| | Gaussian | gSDE | Gaussian |
+--------------+--------------+--------------+--------------+
| HalfCheetah | 2757 +/- 53 | 2984 +/- 202 | 2774 +/- 35 |
+--------------+--------------+--------------+--------------+
| Ant | 3146 +/- 35 | 3102 +/- 37 | 3305 +/- 43 |
+--------------+--------------+--------------+--------------+
| Hopper | 2422 +/- 168 | 2262 +/- 1 | 2429 +/- 126 |
+--------------+--------------+--------------+--------------+
| Walker2D | 2184 +/- 54 | 2136 +/- 67 | 2063 +/- 185 |
+--------------+--------------+--------------+--------------+
How to replicate the results?
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Clone the `rl-zoo repo <https://github.com/DLR-RM/rl-baselines3-zoo>`_:
.. code-block:: bash
git clone https://github.com/DLR-RM/rl-baselines3-zoo
cd rl-baselines3-zoo/
Run the benchmark (replace ``$ENV_ID`` by the envs mentioned above):
.. code-block:: bash
python train.py --algo sac --env $ENV_ID --eval-episodes 10 --eval-freq 10000
Plot the results:
.. code-block:: bash
python scripts/all_plots.py -a sac -e HalfCheetah Ant Hopper Walker2D -f logs/ -o logs/sac_results
python scripts/plot_from_file.py -i logs/sac_results.pkl -latex -l SAC
Parameters
----------
.. autoclass:: SAC
:members:
:inherited-members:
.. _sac_policies:
SAC Policies
-------------
.. autoclass:: MlpPolicy
:members:
:inherited-members:
.. autoclass:: stable_baselines3.sac.policies.SACPolicy
:members:
:noindex:
.. autoclass:: CnnPolicy
:members:
|