Google Colaboratory 中的 openAI Gym NameError

Question

I've just installed openAI gym on Google Colab, but when I try to run 'CartPole-v0' environment as explained here .

Code:

import gym
env = gym.make('CartPole-v0')
for i_episode in range(20):
    observation = env.reset()
    for t in range(100):
        env.render()
        print(observation)
        action = env.action_space.sample()
        observation, reward, done, info = env.step(action)
        if done:
            print("Episode finished after {} timesteps".format(t+1))
            break

I get this:

WARN: gym.spaces.Box autodetected dtype as <class 'numpy.float32'>. Please provide explicit dtype.
---------------------------------------------------------------------------
NameError                                 Traceback (most recent call last)
<ipython-input-19-a81cbed23ce4> in <module>()
      4     observation = env.reset()
      5     for t in range(100):
----> 6         env.render()
      7         print(observation)
      8         action = env.action_space.sample()

/content/gym/gym/core.py in render(self, mode)
    282 
    283     def render(self, mode='human'):
--> 284         return self.env.render(mode)
    285 
    286     def close(self):

/content/gym/gym/envs/classic_control/cartpole.py in render(self, mode)
    104 
    105         if self.viewer is None:
--> 106             from gym.envs.classic_control import rendering
    107             self.viewer = rendering.Viewer(screen_width, screen_height)
    108             l,r,t,b = -cartwidth/2, cartwidth/2, cartheight/2, -cartheight/2

/content/gym/gym/envs/classic_control/rendering.py in <module>()
     21 
     22 try:
---> 23     from pyglet.gl import *
     24 except ImportError as e:
     25     reraise(prefix="Error occured while running `from pyglet.gl import *`",suffix="HINT: make sure you have OpenGL install. On Ubuntu, you can run 'apt-get install python-opengl'. If you're running on a server, you may need a virtual frame buffer; something like this should work: 'xvfb-run -s \"-screen 0 1400x900x24\" python <your_script.py>'")

/usr/local/lib/python3.6/dist-packages/pyglet/gl/__init__.py in <module>()
    225     else:
    226         from .carbon import CarbonConfig as Config
--> 227 del base
    228 
    229 # XXX remove

NameError: name 'base' is not defined

The problem is the same in this question about NameError in openAI gym

Nothing is being rendered. I don't know how I could use this in google colab: 'xvfb-run -s \\"-screen 0 1400x900x24\\" python <your_script.py>'"

Answer 1

One way to render gym environment in google colab is to use pyvirtualdisplay and store rgb frame array while running environment. Environment frames can be animated using animation feature of matplotlib and HTML function used for Ipython display module. You can find the implementation here . Make sure you install required libraries which you can find in the first cell of the colab. In case the first link for google colab doesn't work you can see this one .

Answer 2

The Gym will normally render the display using GL, on your screen.

But Colab is run on the web as a notebook, it can't display directly to your screen. It can only show the result through HTML.

If someone modifies the Gym to maniplulate WebGL, maybe someday. But not now.

Answer 3

Javier, Could you find any solution to this issue? I am trying to use the OenAIs new environment "gym retro" and getting same kind of error when calling make. But as you said I think using xvfb should resolve the issue and let the program run, but of course we wouldn't be able to see the environment graphically. But the issue is that does not allow xvfb to run in the background! xvfb :99 & raises OSError: Background processes not supported.

Answer 4

我在这里看到了一个合适的答案。

pip install pyglet==1.5.11

Answer 5

Just copy paste this

%%bash

# install required system dependencies
apt-get install -y xvfb x11-utils

# install required python dependencies (might need to install additional gym extras depending)
pip install gym[box2d]==0.17.* pyvirtualdisplay==0.2.* PyOpenGL==3.1.* PyOpenGL-accelerate==3.1.*

#import
import pyvirtualdisplay
_display = pyvirtualdisplay.Display(visible=0,  # remember to use visible=0 and not False
                                    size=(1400, 900))
_ = _display.start()

#check
!echo $DISPLAY