Gymnasium/tests/wrappers/test_atari_preprocessing.py

import numpy as np
import gym
from gym.wrappers import AtariPreprocessing
import pytest

pytest.importorskip("gym.envs.atari")


@pytest.fixture(scope="module")
def env_fn():
    return lambda: gym.make("PongNoFrameskip-v4")


def test_atari_preprocessing_grayscale(env_fn):
    import cv2

    env1 = env_fn()
    env2 = AtariPreprocessing(
        env_fn(), screen_size=84, grayscale_obs=True, frame_skip=1, noop_max=0
    )
    env3 = AtariPreprocessing(
        env_fn(), screen_size=84, grayscale_obs=False, frame_skip=1, noop_max=0
    )
    env4 = AtariPreprocessing(
        env_fn(),
        screen_size=84,
        grayscale_obs=True,
        frame_skip=1,
        noop_max=0,
        grayscale_newaxis=True,
    )
    obs1 = env1.reset(seed=0)
    obs2 = env2.reset(seed=0)
    obs3 = env3.reset(seed=0)
    obs4 = env4.reset(seed=0)
    assert env1.observation_space.shape == (210, 160, 3)
    assert env2.observation_space.shape == (84, 84)
    assert env3.observation_space.shape == (84, 84, 3)
    assert env4.observation_space.shape == (84, 84, 1)
    assert obs1.shape == (210, 160, 3)
    assert obs2.shape == (84, 84)
    assert obs3.shape == (84, 84, 3)
    assert obs4.shape == (84, 84, 1)
    assert np.allclose(obs3, cv2.resize(obs1, (84, 84), interpolation=cv2.INTER_AREA))
    obs3_gray = cv2.cvtColor(obs3, cv2.COLOR_RGB2GRAY)
    # the edges of the numbers do not render quite the same in the grayscale, so we ignore them
    assert np.allclose(obs2[10:38], obs3_gray[10:38])
    # the paddle also do not render quite the same
    assert np.allclose(obs2[44:], obs3_gray[44:])
    # now add a channel axis and re-test
    obs3_gray = obs3_gray.reshape(84, 84, 1)
    assert np.allclose(obs4[10:38], obs3_gray[10:38])
    assert np.allclose(obs4[44:], obs3_gray[44:])

    env1.close()
    env2.close()
    env3.close()
    env4.close()


def test_atari_preprocessing_scale(env_fn):
    # arbitrarily chosen number for stepping into env. and ensuring all observations are in the required range
    max_test_steps = 10

    for grayscale in [True, False]:
        for scaled in [True, False]:
            env = AtariPreprocessing(
                env_fn(),
                screen_size=84,
                grayscale_obs=grayscale,
                scale_obs=scaled,
                frame_skip=1,
                noop_max=0,
            )
            obs = env.reset().flatten()
            done, step_i = False, 0
            max_obs = 1 if scaled else 255
            assert (0 <= obs).all() and (
                obs <= max_obs
            ).all(), "Obs. must be in range [0,{}]".format(max_obs)
            while not done or step_i <= max_test_steps:
                obs, _, done, _ = env.step(env.action_space.sample())
                obs = obs.flatten()
                assert (0 <= obs).all() and (
                    obs <= max_obs
                ).all(), "Obs. must be in range [0,{}]".format(max_obs)
                step_i += 1

            env.close()