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lit_sb3.wrappers.atari.sticky_action

[docs] module lit_sb3.wrappers.atari.sticky_action

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import gymnasium as gym
import numpy as np

from lit_sb3.core.types import AtariResetReturn, AtariStepReturn


class StickyActionEnv(gym.Wrapper[np.ndarray, int, np.ndarray, int]):
    """Sticky action.

    Paper: https://arxiv.org/abs/1709.06009
    Official implementation: https://github.com/mgbellemare/Arcade-Learning-Environment

    Args:
        env: Environment to wrap
        action_repeat_probability: Probability of repeating the last action
    """

    def __init__(self, env: gym.Env, action_repeat_probability: float) -> None:
        super().__init__(env)
        self.action_repeat_probability = action_repeat_probability
        assert env.unwrapped.get_action_meanings()[0] == "NOOP"  # type: ignore[attr-defined]

    def reset(self, **kwargs) -> AtariResetReturn:
        self._sticky_action = 0  # NOOP
        return self.env.reset(**kwargs)

    def step(self, action: int) -> AtariStepReturn:
        if self.np_random.random() >= self.action_repeat_probability:
            self._sticky_action = action
        return self.env.step(self._sticky_action)