DDPG-paper-implementation

Implementation of Continuous control with deep reinforcement learning paper together with Stochastic Weighted Average (using pytorch) for a better stability

File descriptions:

1. DDPG.py - main file where DDPG traning, testing and plotting results is defined. Current version uses torchcontrib’s SWA version, SWA_start variable is set in timestep units.
2. utils.py - utils classes and functions. Main utils:
   • ReplayBuffer - List of all past states and their information ('state', 'action', 'next_state', 'reward', 'terminal')
   • OU_Noise - Ornstein–Uhlenbeck process noise
3. requirements.txt - python dependencies. Install by using pip install -r /path/to/requirements.txt

Encountered issues:

• I’m using mixture of Adam and SWA, setting SWA to 1/5th learning rate of Adam in the moment of swapping, I haven’t yet tested with SGD, since convergences time takes ages
  
• Unable to normalize self-implemented SWA due to being unable to connect DataLoader function together with the gym environment
  

Further improvements:

There is still a lot of room for improvement, further testing and fine-tunning some of them include:

• Using different optimizers: Adam/SGD/AdaGrad with different learning rates & learning rate decays
• learning rate decays based on current convergence
• Swapping SWA weights and continuing the training
• Using different type Noise
• Changing the size of the buffer to smaller over time so that we only experience the most recent states
• Different neural network weight initializations, layer sizes, Actor/Critic architecture (more research on the impact of size/number of hidden layers to be conducted)