garage.envs.wrappers.max_and_skip

Max and Skip wrapper for gym.Env.

class MaxAndSkip(env, skip=4)

Bases: gym.Wrapper

Inheritance diagram of garage.envs.wrappers.max_and_skip.MaxAndSkip

Max and skip wrapper for gym.Env.

It returns only every skip-th frame. Action are repeated and rewards are sum for the skipped frames.

It also takes element-wise maximum over the last two consecutive frames, which helps algorithm deal with the problem of how certain Atari games only render their sprites every other game frame.

Parameters
  • env (gym.Env) – The environment to be wrapped.

  • skip (int) – The environment only returns skip-th frame.

metadata
reward_range
action_space
observation_space
step(self, action)

Repeat action, sum reward, and max over last two observations.

Parameters

action (int) – action to take in the atari environment.

Returns

observation of shape \((O*,)\) representating

the max values over the last two oservations.

float: Reward for this step bool: Termination signal dict: Extra information from the environment.

Return type

np.ndarray

reset(self)

gym.Env reset.

Returns

observaion of shape \((O*,)\).

Return type

np.ndarray

property spec(self)
classmethod class_name(cls)
render(self, mode='human', **kwargs)

Renders the environment.

The set of supported modes varies per environment. (And some environments do not support rendering at all.) By convention, if mode is:

  • human: render to the current display or terminal and return nothing. Usually for human consumption.

  • rgb_array: Return an numpy.ndarray with shape (x, y, 3), representing RGB values for an x-by-y pixel image, suitable for turning into a video.

  • ansi: Return a string (str) or StringIO.StringIO containing a terminal-style text representation. The text can include newlines and ANSI escape sequences (e.g. for colors).

Note

Make sure that your class’s metadata ‘render.modes’ key includes

the list of supported modes. It’s recommended to call super() in implementations to use the functionality of this method.

Parameters

mode (str) – the mode to render with

Example:

class MyEnv(Env):

metadata = {‘render.modes’: [‘human’, ‘rgb_array’]}

def render(self, mode=’human’):
if mode == ‘rgb_array’:

return np.array(…) # return RGB frame suitable for video

elif mode == ‘human’:

… # pop up a window and render

else:

super(MyEnv, self).render(mode=mode) # just raise an exception

close(self)

Override close in your subclass to perform any necessary cleanup.

Environments will automatically close() themselves when garbage collected or when the program exits.

seed(self, seed=None)

Sets the seed for this env’s random number generator(s).

Note

Some environments use multiple pseudorandom number generators. We want to capture all such seeds used in order to ensure that there aren’t accidental correlations between multiple generators.

Returns

Returns the list of seeds used in this env’s random

number generators. The first value in the list should be the “main” seed, or the value which a reproducer should pass to ‘seed’. Often, the main seed equals the provided ‘seed’, but this won’t be true if seed=None, for example.

Return type

list<bigint>

compute_reward(self, achieved_goal, desired_goal, info)
property unwrapped(self)

Completely unwrap this env.

Returns

The base non-wrapped gym.Env instance

Return type

gym.Env