Python
A toolkit for developing and comparing reinforcement learning algorithms.

gym

OpenAI Gym is a toolkit for developing and comparing reinforcement learning algorithms. This is the gym open-source library, which gives you access to an ever-growing variety of environments.

gym makes no assumptions about the structure of your agent, and is compatible with any numerical computation library, such as TensorFlow or Theano. You can use it from Python code, and soon from other languages.

If you're not sure where to start, we recommend beginning with the docs on our site.

Basics

There are two basic concepts in reinforcement learning: the environment (namely, the outside world) and the agent (namely, the algorithm you are writing). The agent sends actions to the environment, and the environment replies with observations and rewards (that is, a score).

The core gym interface is Env, which is the unified environment interface. There is no interface for agents; that part is left to you. The following are the Env methods you should know:

• reset(self): Reset the environment's state. Returns observation.
• step(self, action): Step the environment by one timestep. Returns observation, action, reward, done.
• render(self, mode='human', close=False): Render one frame of the environment. The default mode will do something human friendly, such as pop up a window. Passing the close flag signals the renderer to close any such windows.

Installation

You can perform a minimal install of gym with:

git clone https://github.com/openai/gym.git
cd gym
pip install -e .

If you prefer, you can do a minimal install of the packaged version directly from PyPI:

pip install gym

You'll be able to run a few environments right away:

• algorithmic
• toy_text
• classic_control (you'll need pyglet to render though)

We recommend playing with those environments at first, and then later installing the dependencies for the remaining environments.

Installing everything

Once you're ready to install everything, run pip install -e .[all] (or pip install gym[all]).

MuJoCo has a proprietary dependency we can't set up for you. Follow the instructions in the mujoco-py package for help.

For the install to succeed, you'll need to have some system packages installed. We'll build out the list here over time; please let us know what you end up installing on your platform.

On OSX:

brew install cmake

On Ubuntu 14.04:

apt-get install -y python-numpy python-dev cmake zlib1g-dev libjpeg-dev xvfb libav-tools xorg-dev python-opengl

Supported systems

We currenty support Python 2.7 on Linux and OSX.

We will expand support to Python 3 and Windows based on demand. We will also soon ship a Docker container exposing OpenAI Gym as an API callable from any platform.

Pip version

To run pip install -e .[all], you'll need a semi-recent pip. Please make sure your pip is at least at version 1.5.0. You can upgrade using the following: pip install --ignore-installed pip. Alternatively, you can open setup.py and install the dependencies by hand.

Installing dependencies for specific environments

If you'd like to install the dependencies for only specific environments, see setup.py. We maintain the lists of dependencies on a per-environment group basis.

Environments

The code for each environment group is housed in its own subdirectory gym/envs. The specification of each task is in gym/envs/__init__.py. It's worth browsing through both.

Algorithmic

These are a variety of algorithmic tasks, such as learning to copy a sequence.

import gym
env = gym.make('Copy-v0')
env.reset()
env.render()

Atari

The Atari environments are a variety of Atari video games. If you didn't do the full install, you can install dependencies via pip install -e .[atari] (you'll need cmake installed) and then get started as follow:

import gym
env = gym.make('SpaceInvaders-v0')
env.reset()
env.render()

This will install atari-py, which automatically compiles the Arcade Learning Environment. This can take quite a while (a few minutes on a decent laptop), so just be prepared.

Board games

The board game environments are a variety of board games. If you didn't do the full install, you can install dependencies via pip install -e .[board_game] (you'll need cmake installed) and then get started as follow:

import gym
env = gym.make('Go9x9-v0')
env.reset()
env.render()

Classic control

These are a variety of classic control tasks, which would appear in a typical reinforcement learning textbook. If you didn't do the full install, you will need to run pip install -e .[classic_control] to enable rendering. You can get started with them via:

import gym
env = gym.make('CartPole-v0')
env.reset()
env.render()

MuJoCo

MuJoCo is a physics engine which can do very detailed efficient simulations with contacts. It's not open-source, so you'll have to follow the instructions in mujoco-py to set it up. You'll have to also run pip install -e .[mujoco] if you didn't do the full install.

import gym
env = gym.make('Humanoid')
env.reset()
env.render()

Toy text

Toy environments which are text-based. There's no extra dependency to install, so to get started, you can just do:

import gym
env = gym.make('FrozenLake-v0')
env.reset()
env.render()

Examples

See the examples directory.

• Run examples/agents/random_agent.py to run an simple random agent and upload the results to the scoreboard.
• Run examples/agents/cem.py to run an actual learning agent (using the cross-entropy method) and upload the results to the scoreboard.
• Run examples/scripts/list_envs to generate a list of all environments. (You see also just browse the list on our site. - Run examples/scripts/upload to upload the recorded output from random_agent.py or cem.py. Make sure to obtain an API key.

Testing

We are using nose2 for tests. You can run them via:

nose2

You can also run tests in a specific directory by using the -s option, or by passing in the specific name of the test. See the nose2 docs for more details.