[Feature Request] Support wrapper MaxAndSkipEnv for Atari

[LuciusMos]

Motivation

For Atari, you provide some built-in wrappers like OpenAI Baselines. OpenAI Baselines' wrappers include MaxAndSkipEnv. However I cannot find it in your built-in wrappers.

Solution

Can you explain why, and whether it is possible to support this wrapper?

Alternatives

Additional context

Checklist

• I have checked that there is no similar issue in the repo (required)

[Trinkle23897]

MaxAndSkip steps n times and return maximum(obs[-2], obs[-1]). This is implemented in envpool. frame_skip argument is for that purpose.

envpool/envpool/atari/atari_env.h

Lines 185 to 200 in a95e81a

	int skip_id = frame_skip_;
	for (; skip_id > 0 && !done_; --skip_id) {
	reward += env_->act(action_set_[act]);
	done_ = env_->game_over();
	if (skip_id <= 2) { // put final two frames in to maxpool buffer
	uint8_t* ale_screen_data = env_->getScreen().getArray();
	uint8_t* ptr = static_cast<uint8_t*>(maxpool_buf_[2 - skip_id].data());
	if (gray_scale_) {
	env_->theOSystem->colourPalette().applyPaletteGrayscale(
	ptr, ale_screen_data, kRawSize);
	} else {
	env_->theOSystem->colourPalette().applyPaletteRGB(
	ptr, ale_screen_data, kRawSize);
	}
	}
	}

[LuciusMos]

Thank you so much!