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Gymnasium/docs/content/gym_compatibility.md
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contents Compatibility With Gym

Compatibility with Gym

Gymnasium provides a number of compatibility methods for a range of Environment implementations.

Loading OpenAI Gym environments

For environments that are registered solely in OpenAI Gym, it is still possible to import environments within Gymnasium. Introduced in Gymnasium v0.26.3, in gymnasium.make, if the environment id doesn't exist in the gymnasium registry then a check if done to see if the environment is registered in Gym. If it is, then we will make environment using the gym's registration information.

An example of this is atari 0.8.0 which does not have a gymnasium implementation currently.

import gymnasium as gym
env = gym.make("ALE/Pong-v5")

< v0.22 Environment Compatibility

A number of environments have not updated to the recent Gym changes, in particular since v0.21. Therefore, to increase backward compatibility, Gym and Gymnasium v0.26+ include an apply_api_compatibility in {eval-rst}:py:meth:gymnasium.make parameter that applies a wrappers to convert v0.21 environment to the v0.26 API.

Step API Compatibility

If environments implement the (old) done step API, Gymnasium provides both functions ({eval-rst}:py:meth:gymnasium.utils.step_api_compatibility.convert_to_terminated_truncated_step_api) and wrappers ({eval-rst}:py:meth:gymnasium.wrappers.StepAPICompatibility) that will convert the step function to the (new) termination and truncation step API.