Status: Maintenance (expect bug fixes and minor updates)

mujoco-py

MuJoCo is a physics engine for detailed, efficient rigid body simulations with contacts. mujoco-py allows using MuJoCo from Python 3.

This library has been updated to be compatible with MuJoCo version 2.1 released on 2021-10-18.

Synopsis

Requirements

The following platforms are currently supported:

• Linux with Python 3.6+. See the Dockerfile for the canonical list of system dependencies.
• OS X with Python 3.6+.

The following platforms are DEPRECATED and unsupported:

• Windows support has been DEPRECATED and removed in 2.0.2.0. One known good past version is 1.50.1.68.
• Python 2 has been DEPRECATED and removed in 1.50.1.0. Python 2 users can stay on the 0.5 branch. The latest release there is 0.5.7 which can be installed with pip install mujoco-py==0.5.7.

Install MuJoCo

1. Download the MuJoCo version 2.1 binaries for Linux or OSX.
2. Extract the downloaded mujoco210 directory into ~/.mujoco/mujoco210.

If you want to specify a nonstandard location for the package, use the env variable MUJOCO_PY_MUJOCO_PATH.

Install and use mujoco-py

To include mujoco-py in your own package, add it to your requirements like so:

mujoco-py<2.2,>=2.1

To play with mujoco-py interactively, follow these steps:

$ pip3 install -U 'mujoco-py<2.2,>=2.1'
$ python3
import mujoco_py
import os
mj_path = mujoco_py.utils.discover_mujoco()
xml_path = os.path.join(mj_path, 'model', 'humanoid.xml')
model = mujoco_py.load_model_from_path(xml_path)
sim = mujoco_py.MjSim(model)

print(sim.data.qpos)
# [0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0. 0.]

sim.step()
print(sim.data.qpos)
# [-2.09531783e-19  2.72130735e-05  6.14480786e-22 -3.45474715e-06
#   7.42993721e-06 -1.40711141e-04 -3.04253586e-04 -2.07559344e-04
#   8.50646247e-05 -3.45474715e-06  7.42993721e-06 -1.40711141e-04
#  -3.04253586e-04 -2.07559344e-04 -8.50646247e-05  1.11317030e-04
#  -7.03465386e-05 -2.22862221e-05 -1.11317030e-04  7.03465386e-05
#  -2.22862221e-05]

See the full documentation for advanced usage.

Troubleshooting

You're on MacOS and you see clang: error: unsupported option '-fopenmp'

If this happend during installation or just running python -c "import mujoco_py" then the issue seems to be related to this and the TL;DR is that for macOS the default compiler Apple clang LLVM does not support openmp. So you can try to install another clang/llvm installation. For example (requires brew):

brew install llvm
brew install boost
brew install hdf5

# Add this to your .bashrc/.zshrc:
export PATH="/usr/local/opt/llvm/bin:$PATH"

export CC="/usr/local/opt/llvm/bin/clang"
export CXX="/usr/local/opt/llvm/bin/clang++"
export CXX11="/usr/local/opt/llvm/bin/clang++"
export CXX14="/usr/local/opt/llvm/bin/clang++"
export CXX17="/usr/local/opt/llvm/bin/clang++"
export CXX1X="/usr/local/opt/llvm/bin/clang++"

export LDFLAGS="-L/usr/local/opt/llvm/lib"
export CPPFLAGS="-I/usr/local/opt/llvm/include"

Note: Don't forget to source your .bashrc/.zshrc after editing it and try to install mujoco-py again:

# Make sure your python environment is activated
pip install -U 'mujoco-py<2.2,>=2.1'

Missing GLFW

A common error when installing is:

raise ImportError("Failed to load GLFW3 shared library.")

Which happens when the glfw python package fails to find a GLFW dynamic library.

MuJoCo ships with its own copy of this library, which can be used during installation.

Add the path to the mujoco bin directory to your dynamic loader:

LD_LIBRARY_PATH=$HOME/.mujoco/mujoco210/bin pip install mujoco-py

This is particularly useful on Ubuntu 14.04, which does not have a GLFW package.

Ubuntu installtion troubleshooting

Because mujoco_py has compiled native code that needs to be linked to a supplied MuJoCo binary, it's installation on linux can be more challenging than pure Python source packages.

To install mujoco-py on Ubuntu, make sure you have the following libraries installed:

sudo apt install libosmesa6-dev libgl1-mesa-glx libglfw3

If you installed above libraries and you still see an error that -lGL cannot be found, most likely you need to create the symbolic link directly:

sudo ln -s /usr/lib/x86_64-linux-gnu/libGL.so.1 /usr/lib/x86_64-linux-gnu/libGL.so

Usage Examples

A number of examples demonstrating some advanced features of mujoco-py can be found in examples/. These include:

• body_interaction.py: shows interactions between colliding bodies
• disco_fetch.py: shows how TextureModder can be used to randomize object textures
• internal_functions.py: shows how to call raw mujoco functions like mjv_room2model
• markers_demo.py: shows how to add visualization-only geoms to the viewer
• serialize_model.py: shows how to save and restore a model
• setting_state.py: shows how to reset the simulation to a given state
• tosser.py: shows a simple actuated object sorting robot application

See the full documentation for advanced usage.

Development

To run the provided unit and integrations tests:

make test

To test GPU-backed rendering, run:

make test_gpu

This is somewhat dependent on internal OpenAI infrastructure at the moment, but it should run if you change the Makefile parameters for your own setup.

Changelog

• 03/08/2018: We removed MjSimPool, because most of benefit one can get with multiple processes having single simulation.

Credits

mujoco-py is maintained by the OpenAI Robotics team. Contributors include:

• Alex Ray
• Bob McGrew
• Jonas Schneider
• Jonathan Ho
• Peter Welinder
• Wojciech Zaremba
• Jerry Tworek