Danijar Hafner, Timothy Lillicrap, Ian Fischer, Ruben Villegas, David Ha, Honglak Lee, James Davidson

This project provides the open source implementation of the PlaNet agent introduced in Learning Latent Dynamics for Planning from Pixels. PlaNet is a purely model-based reinforcement learning algorithm that solves control tasks from images by efficient planning in a learned latent space. PlaNet competes with top model-free methods in terms of final performance and training time while using substantially less interaction with the environment.

If you find this open source release useful, please reference in your paper:

@inproceedings{hafner2019planet,
  title={Learning Latent Dynamics for Planning from Pixels},
  author={Hafner, Danijar and Lillicrap, Timothy and Fischer, Ian and Villegas, Ruben and Ha, David and Lee, Honglak and Davidson, James},
  booktitle={International Conference on Machine Learning},
  pages={2555--2565},
  year={2019}
}

PlaNet models the world as a compact sequence of hidden states. For planning, we first encode the history of past images into the current state. From there, we efficiently predict future rewards for multiple action sequences in latent space. We execute the first action of the best sequence found and replan after observing the next image.

Find more information:

• Google AI Blog post
• Project website
• PDF paper

To train an agent, install the dependencies and then run:

python3 -m planet.scripts.train --logdir /path/to/logdir --params '{tasks: [cheetah_run]}'

The code prints nan as the score for iterations during which no summaries were computed.

The available tasks are listed in scripts/tasks.py. The default parameters can be found in scripts/configs.py. To run the experiments from our paper, pass the following parameters to --params {...} in addition to the list of tasks:

Please note that the agent has seen some improvements so the results may be a bit different now.

These are good places to start when modifying the code:

Tips for development:

• You can set --config debug to reduce the episode length, batch size, and collect data more freqnently. This helps to quickly reach all parts of the code.
• You can use --num_runs 1000 --resume_runs False to automatically start new runs in sub directories of the logdir every time to execute the script.
• Environments live in separate processes by default. Some environments work better when separated into threads instead by specifying --params '{isolate_envs: thread}'.

The code was tested under Ubuntu 18 and uses these packages:

• tensorflow-gpu==1.13.1
• tensorflow_probability==0.6.0
• dm_control (egl rendering option recommended)
• gym
• scikit-image
• scipy
• ruamel.yaml
• matplotlib

Disclaimer: This is not an official Google product.