torchrl.envs.GymEnv(*args, **kwargs)[source]

OpenAI Gym environment wrapper constructed by environment ID directly.

Works accross gymnasium and OpenAI/gym.

  • env_name (str) – the environment id registered in gym.registry.

  • categorical_action_encoding (bool, optional) – if True, categorical specs will be converted to the TorchRL equivalent (, otherwise a one-hot encoding will be used ( Defaults to False.

Keyword Arguments:
  • num_envs (int, optional) – the number of envs to run in parallel. Defaults to None (a single env is to be run). AsyncVectorEnv will be used by default.

  • disable_env_checker (bool, optional) – for gym > 0.24 only. If True (default for these versions), the environment checker won’t be run.

  • from_pixels (bool, optional) – if True, an attempt to return the pixel observations from the env will be performed. By default, these observations will be written under the "pixels" entry. The method being used varies depending on the gym version and may involve a wrappers.pixel_observation.PixelObservationWrapper. Defaults to False.

  • pixels_only (bool, optional) – if True, only the pixel observations will be returned (by default under the "pixels" entry in the output tensordict). If False, observations (eg, states) and pixels will be returned whenever from_pixels=True. Defaults to True.

  • frame_skip (int, optional) – if provided, indicates for how many steps the same action is to be repeated. The observation returned will be the last observation of the sequence, whereas the reward will be the sum of rewards across steps.

  • device (torch.device, optional) – if provided, the device on which the data is to be cast. Defaults to torch.device("cpu").

  • batch_size (torch.Size, optional) – the batch size of the environment. Should match the leading dimensions of all observations, done states, rewards, actions and infos. Defaults to torch.Size([]).

  • allow_done_after_reset (bool, optional) – if True, it is tolerated for envs to be done just after reset() is called. Defaults to False.


available_envs (List[str]) – the list of envs that can be built.


If an attribute cannot be found, this class will attempt to retrieve it from the nested env:

>>> from torchrl.envs import GymEnv
>>> env = GymEnv("Pendulum-v1")
>>> print(env.spec.max_episode_steps)


>>> from torchrl.envs import GymEnv
>>> env = GymEnv("Pendulum-v1")
>>> td = env.rand_step()
>>> print(td)
        action: Tensor(shape=torch.Size([1]), device=cpu, dtype=torch.float32, is_shared=False),
        next: TensorDict(
                done: Tensor(shape=torch.Size([1]), device=cpu, dtype=torch.bool, is_shared=False),
                observation: Tensor(shape=torch.Size([3]), device=cpu, dtype=torch.float32, is_shared=False),
                reward: Tensor(shape=torch.Size([1]), device=cpu, dtype=torch.float32, is_shared=False),
                terminated: Tensor(shape=torch.Size([1]), device=cpu, dtype=torch.bool, is_shared=False),
                truncated: Tensor(shape=torch.Size([1]), device=cpu, dtype=torch.bool, is_shared=False)},
>>> print(env.available_envs)
['ALE/Adventure-ram-v5', 'ALE/Adventure-v5', 'ALE/AirRaid-ram-v5', 'ALE/AirRaid-v5', 'ALE/Alien-ram-v5', 'ALE/Alien-v5',


If both OpenAI/gym and gymnasium are present in the virtual environment, one can swap backend using set_gym_backend():

>>> from torchrl.envs import set_gym_backend, GymEnv
>>> with set_gym_backend("gym"):
...     env = GymEnv("Pendulum-v1")
...     print(env._env)
<class 'gym.wrappers.time_limit.TimeLimit'>
>>> with set_gym_backend("gymnasium"):
...     env = GymEnv("Pendulum-v1")
...     print(env._env)
<class 'gymnasium.wrappers.time_limit.TimeLimit'>


info dictionaries will be read using default_info_dict_reader if no other reader is provided. To provide another reader, refer to set_info_dict_reader(). To automatically register the info_dict content, refer to torchrl.envs.GymLikeEnv.auto_register_info_dict().


Access comprehensive developer documentation for PyTorch

View Docs


Get in-depth tutorials for beginners and advanced developers

View Tutorials


Find development resources and get your questions answered

View Resources