State-of-the-art Model-free Reinforcement Learning Algorithms

PyTorch and Tensorflow 2.0 implementation of state-of-the-art model-free reinforcement learning algorithms on both Openai gym environments and a self-implemented Reacher environment.

Algorithms include Soft Actor-Critic (SAC), Deep Deterministic Policy Gradient (DDPG), Twin Delayed DDPG (TD3), Actor-Critic (AC/A2C), Proximal Policy Optimization (PPO), QT-Opt (including Cross-entropy (CE) Method), PointNet, Transporter, Recurrent Policy Gradient, Soft Decision Tree, etc.

Please note that this repo is more of a personal collection of algorithms I implemented and tested during my research and study period, rather than an official open-source library/package for usage. However, I think it could be helpful to share it with others and I'm expecting useful discussions on my implementations. But I didn't spend much time on cleaning or structuring the code. As you may notice that there may be several versions of implementation for each algorithm, I intentionally show all of them here for you to refer and compare. Also, this repo contains only PyTorch Implementation.

For official libraries of RL algorithms, I provided the following two with TensorFlow 2.0 + TensorLayer 2.0:

• RL Tutorial (Status: Released) contains RL algorithms implementation as tutorials with simple structures.

• RLzoo (Status: Released) is a baseline implementation with high-level API supporting a variety of popular environments, with more hierarchical structures for simple usage.

Since Tensorflow 2.0 has already incorporated the dynamic graph construction instead of the static one, it becomes a trivial work to transfer the RL code between TensorFlow and PyTorch.

Contents:

• Two versions of Soft Actor-Critic (SAC) are implemented.

  SAC Version 1:

  sac.py: using state-value function.

  paper: https://arxiv.org/pdf/1801.01290.pdf

  SAC Version 2:

  sac_v2.py: using target Q-value function instead of state-value function.

  paper: https://arxiv.org/pdf/1812.05905.pdf

• Deep Deterministic Policy Gradient (DDPG):

  ddpg.py: implementation of DDPG.

• Twin Delayed DDPG (TD3):

  td3.py: implementation of TD3.

  paper: https://arxiv.org/pdf/1802.09477.pdf

• Proximal Policy Optimization (PPO):

  For continuous environments, two versions are implemented:

  Version 1: ppo_continuous.py and ppo_continuous_multiprocess.py

  Version 2: ppo_continuous2.py and ppo_continuous_multiprocess2.py

  For discrete environment:

  ppo_gae_discrete.py: with Generalized Advantage Estimation (GAE)

• Actor-Critic (AC) / A2C:

  ac.py: extensible AC/A2C, easy to change to be DDPG, etc.

  A very extensible version of vanilla AC/A2C, supporting for all continuous/discrete deterministic/non-deterministic cases.

• QT-Opt:

  Two versions are implemented here.

• PointNet for landmarks generation from images with unsupervised learning is implemented here. This method is also used for image-based reinforcement learning as a SOTA algorithm, called Transporter.

  original paper: Unsupervised Learning of Object Landmarksthrough Conditional Image Generation

  paper for RL: Unsupervised Learning of Object Keypointsfor Perception and Control

• Recurrent Policy Gradient:

  rdpg.py: DDPG with LSTM policy.

  td3_lstm.py: TD3 with LSTM policy.

  sac_v2_lstm.py: SAC with LSTM policy.

  References:

  Memory-based control with recurrent neural networks

  Sim-to-Real Transfer of Robotic Control with Dynamics Randomization

• Soft Decision Tree as function approximator for PPO:

  sdt_ppo_gae_discrete.py: replace the network layers of policy in PPO to be a Soft Decision Tree, for achieving explainable RL.

• Maximum a Posteriori Policy Optimisation (MPO):

  todo

  paper: Maximum a Posteriori Policy Optimisation

• Advantage-Weighted Regression (AWR):

  todo

  paper: Advantage-Weighted Regression: Simple and Scalable Off-Policy Reinforcement Learning

Usage:

python ***.py --train

python ***.py --test

Troubleshooting:

If you meet problem "Not imlplemented Error", it may be due to the wrong gym version. The newest gym==0.14 won't work. Install gym==0.7 or gym==0.10 with pip install -r requirements.txt.

Performance:

• SAC for gym Pendulum-v0:

SAC with automatically updating variable alpha for entropy:

It shows that the automatic-entropy update helps the agent to learn faster.

• TD3 for gym Pendulum-v0:

TD3 with deterministic policy:

It seems TD3 with deterministic policy works a little better, but basically similar.

• AC for gym CartPole-v0:

However, vanilla AC/A2C cannot handle the continuous case like gym Pendulum-v0 well.

Citation:

To cite this repository:

@misc{rlalgorithms,
  author = {Zihan Ding},
  title = {Popular-RL-Algorithms},
  year = {2019},
  publisher = {GitHub},
  journal = {GitHub repository},
  howpublished = {\url{https://github.com/quantumiracle/Popular-RL-Algorithms}},
}