garage.envs.wrappers.stack_frames

Stack frames wrapper for gym.Env.

class StackFrames(env, n_frames)

Bases: gym.Wrapper

Inheritance diagram of garage.envs.wrappers.stack_frames.StackFrames

gym.Env wrapper to stack multiple frames.

Useful for training feed-forward agents on dynamic games. Only works with gym.spaces.Box environment with 2D single channel frames.

Parameters:
  • env – gym.Env to wrap.
  • n_frames – number of frames to stack.
Raises:
  • ValueError – If observation space shape is not 2 or
  • environment is not gym.spaces.Box.
observation_space

gym.Env observation space.

spec
unwrapped

Completely unwrap this env.

Returns:The base non-wrapped gym.Env instance
Return type:gym.Env
metadata
reward_range
action_space
reset(self)

gym.Env reset function.

step(self, action)

gym.Env step function.

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)