ARS is a random search method for training linear policies for continuous control problems, based on the paper "Simple random search provides a competitive approach to reinforcement learning."

Our ARS implementation relies on Python 3, OpenAI Gym version 0.9.3, mujoco-py 0.5.7, MuJoCo Pro version 1.31, and the Ray library for parallel computing.

To install OpenAI Gym and MuJoCo dependencies follow the instructions here: https://github.com/openai/gym

To install Ray execute:

pip install ray

For more information on Ray see https://ray.readthedocs.io/en/latest/.

First start Ray by executing a command of the following form:

ray start --head --redis-port=6379 --num-workers=18

This command starts multiple Python processes on one machine for parallel computations with Ray. Set "num_workers=X" for parallelizing ARS across X CPUs. For parallelzing ARS on a cluster follow the instructions here: https://ray.readthedocs.io/en/latest/using-ray-on-a-large-cluster.html.

We recommend using single threaded linear algebra computations by setting:

export MKL_NUM_THREADS=1

To train a policy for HalfCheetah-v1, execute the following command:

python code/ars.py

All arguments passed into ARS are optional and can be modified to train other environments, use different hyperparameters, or use different random seeds. For example, to train a policy for Humanoid-v1, execute the following command:

python code/ars.py --env_name Humanoid-v1 --n_directions 230 --deltas_used 230 --step_size 0.02 --delta_std 0.0075 --n_workers 48 --shift 5

To render a trained policy, execute a command of the following form:

python code/run_policy.py trained_polices/env_name/policy_directory_path/policy_file_name.npz env_name --render

For example, to render Humanoid-v1 with a galloping gait execute:

python code/run_policy.py trained_policies/Humanoid-v1/policy_reward_11600/lin_policy_plus.npz Humanoid-v1 --render