Package Versions

As part of ML-Agents Release 3, we will be versioning the different packages that make up the release.
NOTE: It is strongly recommended that you use packages from the same release together for the best experience.

Major Features and Improvements

com.unity.ml-agents (C#)

• ObservableAttribute was added. Adding the attribute to fields or properties on an Agent will allow it to generate observations via reflection. (#3925, #4006)

ml-agents-envs (Python)

• First version of the Unity Environment Registry (Experimental) has been released. The Environment Registry allows running pre-built Unity environments from Python without installing the Unity editor. More information here (#3967)

gym-unity (Python)

• use_visual and allow_multiple_visual_obs in the UnityToGymWrapper constructor were replaced by allow_multiple_obs which allows one or more visual observations and vector observations to be used simultaneously. (#3981) Thank you @shakenes !

ml-agents (Python)

• When using a Curriculum, the current lesson will resume if training is quit and resumed. As such, the --lesson CLI option has been removed. (#4025)
• In PPO training, beta and epsilon now follow the same decay schedule as learning_rate. Previously they were always decayed. (#3940)

Example Environments

• Added new Walker environments. Improved ragdoll stability/performance. (#4037)

Breaking Changes

ml-agents

• Format for trainer configuration has changed, and the "default" behavior has been deprecated. See the Migration Guide for more details. (#3936)
• Curriculum and Parameter Randomization configurations have been merged into the main training configuration file. Note that this means training configuration files are now environment-specific. (#3791)
• Training artifacts (trained models, summaries) are now found in the results/ directory. (#3829)
  --save-freq CLI option has been removed, and replaced by a checkpoint_interval option in the trainer configuration YAML. (#4034)

ml-agents-envs

• get_behavior_names() and get_behavior_spec() on UnityEnvironment were replaced by the behavior_specs property. (#3946)
• In the Python API, max_step in the TerminalStep and TerminalSteps objects was renamed interrupted. (#3908)

Bug Fixes and Minor Changes

ml-agents

• Unity Player logs are now written out to the results directory. (#3877)
• Run configuration YAML files are written out to the results directory at the end of the run. (#3815)
• When trying to load/resume from a checkpoint created with an earlier version of ML-Agents, a warning will be thrown. (#4035)
• Fixed an issue where SAC would perform too many model updates when resuming from a checkpoint, and too few when using buffer_init_steps. (#4038)

Acknowledgements

Thank you @shakenes, @TPihko, and everyone at Unity for their contributions to this release.