Gymnasium/docs/creating_environments.md

How to create new environments for Gym

• Create a new repo called gym-foo, which should also be a PIP package.

• A good example is https://github.com/openai/gym-soccer.

• It should have at least the following files:

  gym-foo/
    README.md
    setup.py
    gym_foo/
      __init__.py
      envs/
        __init__.py
        foo_env.py
        foo_extrahard_env.py
  

• gym-foo/setup.py should have:

  from setuptools import setup
  
  setup(name='gym_foo',
        version='0.0.1',
        install_requires=['gym']  # And any other dependencies foo needs
  )
  

• gym-foo/gym_foo/__init__.py should have:

  from gym.envs.registration import register
  
  register(
      id='foo-v0',
      entry_point='gym_foo.envs:FooEnv',
  )
  register(
      id='foo-extrahard-v0',
      entry_point='gym_foo.envs:FooExtraHardEnv',
  )
  

• gym-foo/gym_foo/envs/__init__.py should have:

  from gym_foo.envs.foo_env import FooEnv
  from gym_foo.envs.foo_extrahard_env import FooExtraHardEnv
  

• gym-foo/gym_foo/envs/foo_env.py should look something like:

  from typing import Optional
  import gym
  from gym import error, spaces, utils
  from gym.utils import seeding
  
  class FooEnv(gym.Env):
    metadata = {'render.modes': ['human']}
  
    def __init__(self):
      ...
    def step(self, action):
      ...
    def reset(self, seed: Optional[int] = None):
      super().reset(seed=seed)
      ...
    def render(self, mode='human'):
      ...
    def close(self):
      ...
  

• After you have installed your package with pip install -e gym-foo, you can create an instance of the environment with gym.make('gym_foo:foo-v0')