Michael Panchenko b900fdf6f2
Remove kwargs in policy init (#950)
Closes #947 

This removes all kwargs from all policy constructors. While doing that,
I also improved several names and added a whole lot of TODOs.

## Functional changes:

1. Added possibility to pass None as `critic2` and `critic2_optim`. In
fact, the default behavior then should cover the absolute majority of
cases
2. Added a function called `clone_optimizer` as a temporary measure to
support passing `critic2_optim=None`

## Breaking changes:

1. `action_space` is no longer optional. In fact, it already was
non-optional, as there was a ValueError in BasePolicy.init. So now
several examples were fixed to reflect that
2. `reward_normalization` removed from DDPG and children. It was never
allowed to pass it as `True` there, an error would have been raised in
`compute_n_step_reward`. Now I removed it from the interface
3. renamed `critic1` and similar to `critic`, in order to have uniform
interfaces. Note that the `critic` in DDPG was optional for the sole
reason that child classes used `critic1`. I removed this optionality
(DDPG can't do anything with `critic=None`)
4. Several renamings of fields (mostly private to public, so backwards
compatible)

## Additional changes: 
1. Removed type and default declaration from docstring. This kind of
duplication is really not necessary
2. Policy constructors are now only called using named arguments, not a
fragile mixture of positional and named as before
5. Minor beautifications in typing and code 
6. Generally shortened docstrings and made them uniform across all
policies (hopefully)

## Comment:

With these changes, several problems in tianshou's inheritance hierarchy
become more apparent. I tried highlighting them for future work.

---------

Co-authored-by: Dominik Jain <d.jain@appliedai.de>
2023-10-08 08:57:03 -07:00
..

Inverse Reinforcement Learning

In inverse reinforcement learning setting, the agent learns a policy from interaction with an environment without reward and a fixed dataset which is collected with an expert policy.

Continuous control

Once the dataset is collected, it will not be changed during training. We use d4rl datasets to train agent for continuous control. You can refer to d4rl to see how to use d4rl datasets.

We provide implementation of GAIL algorithm for continuous control.

Train

You can parse d4rl datasets into a ReplayBuffer , and set it as the parameter expert_buffer of GAILPolicy. irl_gail.py is an example of inverse RL using the d4rl dataset.

To train an agent with BCQ algorithm:

python irl_gail.py --task HalfCheetah-v2 --expert-data-task halfcheetah-expert-v2

GAIL (single run)

task best reward reward curve parameters
HalfCheetah-v2 5177.07 python3 irl_gail.py --task "HalfCheetah-v2" --expert-data-task "halfcheetah-expert-v2"
Hopper-v2 1761.44 python3 irl_gail.py --task "Hopper-v2" --expert-data-task "hopper-expert-v2"
Walker2d-v2 2020.77 python3 irl_gail.py --task "Walker2d-v2" --expert-data-task "walker2d-expert-v2"