Observation mode "pixel" raises AttributeError

[phlippe]

Hi, when trying to create an environment that runs in the observation mode "pixel", the environment crashes due to the attribute self.observation_space not being defined:

from causal_world.envs import CausalWorld
from causal_world.task_generators.task import generate_task

task = generate_task(task_generator_id='stacked_blocks')
env = CausalWorld(task=task,
                  observation_mode='pixel')

Error:

File causalworld.py:238, in CausalWorld._reset_observations_space(self)
    237 def _reset_observations_space(self):
--> 238     if self._observation_mode == "pixel" and self.observation_space is None:
    239         self._stage.select_observations(["goal_image"])
    240         self.observation_space = combine_spaces(
    241             self._robot.get_observation_spaces(),
    242             self._stage.get_observation_spaces())

AttributeError: 'CausalWorld' object has no attribute 'observation_space'

I am not sure if this might be caused by a new gym version. A quick fix is to simply define self.observation_space = None before calling self._reset_observations_space() in the init (line 171).

[ftraeuble]

Thanks for bringing this to our attention. I believe this is indeed due to a new gym version. Could you try to see if you still experience that error with the latest master version?

[phlippe]

Hi @ftraeuble, thanks for checking! Enforcing an older gym version (0.17.2), as in the new master, removes the error for me.