Decision Transformer Interpretability

Docs Here App Here

This project is designed to facilitate mechanistic interpretability of decision transformers as well as RL agents using transformer architectures.

This is achieved via:

• Training scripts for online RL agents using the PPO algorithm. This training script can be used to generate trajectories for training a decision transformer.
• A decision transformer implementation and training script. This implementation is based on the transformer architecture and the decision transformer architecture.
• A streamlit app. This app enables researchers to play minigrid games whilst observing the decision transformer's predictions/activations.

Future work will include:

• creating an interpretability portfolio, expanding various exploratory techniques already present in the streamlit app.
• solving tasks which require memory or language instruction. Many MiniGrid tasks require agents have memory and currently our PPO agent only responds to the last timestep.
• validating hypotheses about model circuits using casual scrubbing.

Write Up

You can find an initial technical report for this project here.

Package Overview

The package contains several important components:

• The environments package which provides utilities for generating environments (mainly focussed on MiniGrid).
• The decision_transformer package which provides utilities for training and evaluating decision transformers (via calibration curves).
• The ppo package which provides utilities for training and evaluating PPO agents.
• The streamlit app which provides a user interface for playing games and observing the decision transformer's predictions/activations.
• The models package which provides the a common trajectory-transformer class so as to keep architectures homogeneous across the project.

Other notable files/folders:

• The scripts folder contains bash scripts which show how to use various interfaces in the project.
• The test folder which contains extensive tests for the projcect.

Example Results

We've successfully trained a decision transformer on several games including DoorKey and Dynamic Obstacles.

Calibration Plot	MiniGrid-Dynamic-Obstacles-8x8-v0, after 6000 batch, episode length 14, RTG 1.0, reward 0.955

I highly recommend playing with the streamlit app if you are interested in this project. It relies heavily on an understanding of the Mathematical Framework for Transformer Circuits.

Running the scripts

Example bash scripts are provided in the scripts folder. They make use of argparse interfaces in the package.

Training a PPO agent

If you set 'track' to true, a weights and biases dashboard will be generated. A trajectories pickle file will be generated in the trajectories folder. This file can be used to train a decision tranformer.

python -m src.run_ppo --exp_name "Test" \
    --seed 1 \
    --cuda \
    --track \
    --wandb_project_name "PPO-MiniGrid" \
    --env_id "MiniGrid-DoorKey-8x8-v0" \
    --view_size 5 \
    --total_timesteps 350000 \
    --learning_rate 0.00025 \
    --num_envs 8 \
    --num_steps 128 \
    --num_minibatches 4 \
    --update_epochs 4 \
    --clip_coef 0.2 \
    --ent_coef 0.01 \
    --vf_coef 0.5 \
    --max_steps 1000 \
    --one_hot_obs

Training a decision transformer

Targeting the trajectories file and setting the model architecture details and hyperparameters, you can run the decision transformer training script.

python -m src.run_decision_transformer \
    --exp_name MiniGrid-Dynamic-Obstacles-8x8-v0-Refactor \
    --trajectory_path trajectories/MiniGrid-Dynamic-Obstacles-8x8-v0bd60729d-dc0b-4294-9110-8d5f672aa82c.pkl \
    --d_model 128 \
    --n_heads 2 \
    --d_mlp 256 \
    --n_layers 1 \
    --learning_rate 0.0001 \
    --batch_size 128 \
    --train_epochs 5000 \
    --test_epochs 10 \
    --n_ctx 3 \
    --pct_traj 1 \
    --weight_decay 0.001 \
    --seed 1 \
    --wandb_project_name DecisionTransformerInterpretability-Dev \
    --test_frequency 1000 \
    --eval_frequency 1000 \
    --eval_episodes 10 \
    --initial_rtg -1 \
    --initial_rtg 0 \
    --initial_rtg 1 \
    --prob_go_from_end 0.1 \
    --eval_max_time_steps 1000 \
    --track True

Note, if you want the training data from the blog post, you can download it like so

cd trajectories
gdown 1UBMuhRrM3aYDdHeJBFdTn1RzXDrCL_sr

Running the streamlit app

To run the streamlit app:

streamlit run app.py

Setting up the environment

I haven't been too careful about this yet. Using python 3.9.15 with the requirements.txt file. We're using the V2 branch of transformer lens and Minigrid 2.1.0.

conda env create --name decision_transformer_interpretability python=3.9.15
conda activate decision_transformer_interpretability
pip install -r requirements.txt

The docker file should work and we can make use of it more when the project is further ahead/if we are alternativing developers frequently and have any differential behavior.

./scripts/build_docker.sh
./scripts/run_docker.sh

Then you can ssh into the docker and a good ide will bring credentials etc.

Development

Tests:

Ensure that the run_tests.sh script is executable:

chmod a+x ./scripts/run_tests.sh

Run the tests. Note: the end to end tests are excluded from the run_test.sh script since they take a while to run. They make wandb dashboards are are useful for debugging but they are not necessary for development.

To run end-to-end tests, you can use the command 'pytest -v --cov=src/ --cov-report=term-missing'. If the trajectories file 'MiniGrid-Dynamic-Obstacles-8x8-v0bd60729d-dc0b-4294-9110-8d5f672aa82c.pkl' is not found in the tests, the 'gdown' command has failed to download it. In that case, download it manually or run 'conda install -c conda-forge gdown' and try again.

./scripts/run_tests.sh

You should see something like this after the tests run. This is the coverage report. Ideally this is 100% but we're not there yet. Furthermore, it will be 100% long before we have enough tests. But if it's 100% and we have performant code with agents training and stuff otherwise working, that's pretty good.

---------- coverage: platform darwin, python 3.9.15-final-0 ----------
Name                                Stmts   Miss  Cover   Missing
-----------------------------------------------------------------
src/__init__.py                         0      0   100%
src/decision_transformer.py           132      8    94%   39, 145, 151, 156-157, 221, 246, 249
src/ppo.py                             20     20     0%   2-28
src/ppo/__init__.py                     0      0   100%
src/ppo/agent.py                      109     10    91%   41, 45, 112, 151-157
src/ppo/compute_adv_vectorized.py      30     30     0%   1-65
src/ppo/memory.py                      88     11    88%   61-64, 119-123, 147-148
src/ppo/my_probe_envs.py               99      9    91%   38, 42-44, 74, 99, 108, 137, 168
src/ppo/train.py                       69      6    91%   58, 74, 94, 98, 109, 113
src/ppo/utils.py                      146     54    63%   41-42, 61-63, 69, 75, 92-96, 110-115, 177-206, 217-235
src/utils.py                           40     17    58%   33-38, 42-65, 73, 76-79
src/visualization.py                   25     25     0%   1-34
-----------------------------------------------------------------
TOTAL                                 758    190    75%

Next Steps

• Getting PPO to work with a transformer architecture.
• Analyse this model/the decision transformer/a behavioural clone and publish the results.
• Get a version of causal-scrubbing working
• Study BabyAI (adapt all models to take an instruction token that is prepended to the context window)

Relevant Projects:

• decision transformers
• gym-minigrid
• transformerlens