Gym: IndexError when running "Pendulum-v0" env with matlab-http-api

[vBarbaros]

Hey guys,

I installed the gym package inside a python-2.7 virtualenv, and was running the Pendulum-v0 env using the binding-matlab/gym_http_client.m from gym-http-api.

When starting the env, an error was constantly rising:
../path_to_my_virtualenv/virtual_gym_npreps/local/lib/python2.7/site-packages/gym/envs/classic_control/pendulum.py", line 37, in _step u = np.clip(u, -self.max_torque, self.max_torque)[0] IndexError: invalid index to scalar variable.

I took off the indexing part and now I can run it properly; apparently, the control u is already a scalar for the pendulum.

Not sure if I should pull a request for this change or the reason I got this error is somewhere in the intermediate steps and u should not be a scalar after all (couldn't see any specs for the Pendulum, but it makes sense to expect a single number for the torque, right), oru should be passed as array, i.e., np.clip([u], ....)

Let me know how to handle this correctly,
Thanks

Addendum: I get this issue when running the Pendulum-v0 on Ubuntu 16.04, but it works perfectly fine when running on Mac

[JadenTravnik]

I also get this issue running on Windows and using the latest repo. I guess passing in the actions as an array is a simple fix.
env.step([action])

[vBarbaros]

Yes, @JadenTravnik , I agree that we could fix it in many ways - passing the action as array, or removing the indexing; I wanted to let them know that something is wrong down the way and maybe the guys who updated the agent know better where they should look for the intruded bug.