Source code for stable_baselines.common.vec_env.vec_frame_stack

import warnings

import numpy as np
from gym import spaces

from stable_baselines.common.vec_env.base_vec_env import VecEnvWrapper

[docs]class VecFrameStack(VecEnvWrapper): """ Frame stacking wrapper for vectorized environment :param venv: (VecEnv) the vectorized environment to wrap :param n_stack: (int) Number of frames to stack """ def __init__(self, venv, n_stack): self.venv = venv self.n_stack = n_stack wrapped_obs_space = venv.observation_space low = np.repeat(wrapped_obs_space.low, self.n_stack, axis=-1) high = np.repeat(wrapped_obs_space.high, self.n_stack, axis=-1) self.stackedobs = np.zeros((venv.num_envs,) + low.shape, low.dtype) observation_space = spaces.Box(low=low, high=high, dtype=venv.observation_space.dtype) VecEnvWrapper.__init__(self, venv, observation_space=observation_space)
[docs] def step_wait(self): observations, rewards, dones, infos = self.venv.step_wait() last_ax_size = observations.shape[-1] self.stackedobs = np.roll(self.stackedobs, shift=-last_ax_size, axis=-1) for i, done in enumerate(dones): if done: if 'terminal_observation' in infos[i]: old_terminal = infos[i]['terminal_observation'] new_terminal = np.concatenate( (self.stackedobs[i, ..., :-last_ax_size], old_terminal), axis=-1) infos[i]['terminal_observation'] = new_terminal else: warnings.warn( "VecFrameStack wrapping a VecEnv without terminal_observation info") self.stackedobs[i] = 0 self.stackedobs[..., -observations.shape[-1]:] = observations return self.stackedobs, rewards, dones, infos
[docs] def reset(self): """ Reset all environments """ obs = self.venv.reset() self.stackedobs[...] = 0 self.stackedobs[..., -obs.shape[-1]:] = obs return self.stackedobs
[docs] def close(self): self.venv.close()