Python library compilation error (Python 3.9, MATLAB R2021b)

Hello all,

I am trying to use a Python library from within MATLAB for Reinforcement Learning. I have followed all the instructions and I have the library correclty installed in my system, using Python 3.9.11, which is supported by MATLAB 2021b. pyenv instruction also shows a correct detection of Python from MATLAB command line. I have also all the needed pip packages installed:

PS C:\Users\alberto.tellaeche> pip list

Package Version

------------------ --------

cffi 1.15.0

cloudpickle 2.0.0

Cython 0.29.28

fasteners 0.17.3

glfw 2.5.1

gym 0.23.1

gym-notices 0.0.6

gym-robotics 0.1.0

imageio 2.16.1

importlib-metadata 4.11.3

mujoco-py 2.1.2.14

numpy 1.22.3

Pillow 9.0.1

pip 22.0.4

pycparser 2.21

pygame 2.1.2

setuptools 58.1.0

zipp 3.7.0

One of the packages installed using "pip install", needs to compile something. I have checked C++ compiled and it is in the path MATLAB looks for it.

When I call the library from MATLAB´s command window:

env = py.gym.make('FetchReach-v1')

I get the following compiling error:

Compiling C:\Python39\lib\site-packages\mujoco_py\cymj.pyx because it changed.

[1/1] Cythonizing C:\Python39\lib\site-packages\mujoco_py\cymj.pyx

running build_ext

building 'mujoco_py.cymj' extension

creating C:\Python39\lib\site-packages\mujoco_py\generated\_pyxbld_2.1.2.14_39_windowsextensionbuilder

creating C:\Python39\lib\site-packages\mujoco_py\generated\_pyxbld_2.1.2.14_39_windowsextensionbuilder\temp.win-amd64-3.9

creating C:\Python39\lib\site-packages\mujoco_py\generated\_pyxbld_2.1.2.14_39_windowsextensionbuilder\temp.win-amd64-3.9\Release

creating C:\Python39\lib\site-packages\mujoco_py\generated\_pyxbld_2.1.2.14_39_windowsextensionbuilder\temp.win-amd64-3.9\Release\Python39

creating C:\Python39\lib\site-packages\mujoco_py\generated\_pyxbld_2.1.2.14_39_windowsextensionbuilder\temp.win-amd64-3.9\Release\Python39\lib

creating C:\Python39\lib\site-packages\mujoco_py\generated\_pyxbld_2.1.2.14_39_windowsextensionbuilder\temp.win-amd64-3.9\Release\Python39\lib\site-packages

creating C:\Python39\lib\site-packages\mujoco_py\generated\_pyxbld_2.1.2.14_39_windowsextensionbuilder\temp.win-amd64-3.9\Release\Python39\lib\site-packages\mujoco_py

creating C:\Python39\lib\site-packages\mujoco_py\generated\_pyxbld_2.1.2.14_39_windowsextensionbuilder\temp.win-amd64-3.9\Release\Python39\lib\site-packages\mujoco_py\gl

C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.23.28105\bin\HostX86\x64\cl.exe /c /nologo /Ox /W3 /GL /DNDEBUG /MD -IC:\Python39\lib\site-packages\mujoco_py -IC:\Users\alberto.tellaeche\.mujoco\mujoco210\include -IC:\Python39\lib\site-packages\numpy\core\include -I.\include -I.\include -IC:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.23.28105\ATLMFC\include -IC:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.23.28105\include -IC:\Program Files (x86)\Windows Kits\NETFXSDK\4.8\include\um -IC:\Program Files (x86)\Windows Kits\10\include\10.0.18362.0\ucrt -IC:\Program Files (x86)\Windows Kits\10\include\10.0.18362.0\shared -IC:\Program Files (x86)\Windows Kits\10\include\10.0.18362.0\um -IC:\Program Files (x86)\Windows Kits\10\include\10.0.18362.0\winrt -IC:\Program Files (x86)\Windows Kits\10\include\10.0.18362.0\cppwinrt /TcC:\Python39\lib\site-packages\mujoco_py/gl/dummyshim.c /FoC:\Python39\lib\site-packages\mujoco_py\generated\_pyxbld_2.1.2.14_39_windowsextensionbuilder\temp.win-amd64-3.9\Release\Python39\lib\site-packages\mujoco_py/gl/dummyshim.obj -fopenmp -w

C:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.23.28105\bin\HostX86\x64\cl.exe /c /nologo /Ox /W3 /GL /DNDEBUG /MD -IC:\Python39\lib\site-packages\mujoco_py -IC:\Users\alberto.tellaeche\.mujoco\mujoco210\include -IC:\Python39\lib\site-packages\numpy\core\include -I.\include -I.\include -IC:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.23.28105\ATLMFC\include -IC:\Program Files (x86)\Microsoft Visual Studio\2019\Community\VC\Tools\MSVC\14.23.28105\include -IC:\Program Files (x86)\Windows Kits\NETFXSDK\4.8\include\um -IC:\Program Files (x86)\Windows Kits\10\include\10.0.18362.0\ucrt -IC:\Program Files (x86)\Windows Kits\10\include\10.0.18362.0\shared -IC:\Program Files (x86)\Windows Kits\10\include\10.0.18362.0\um -IC:\Program Files (x86)\Windows Kits\10\include\10.0.18362.0\winrt -IC:\Program Files (x86)\Windows Kits\10\include\10.0.18362.0\cppwinrt /TcC:\Python39\lib\site-packages\mujoco_py\cymj.c /FoC:\Python39\lib\site-packages\mujoco_py\generated\_pyxbld_2.1.2.14_39_windowsextensionbuilder\temp.win-amd64-3.9\Release\Python39\lib\site-packages\mujoco_py\cymj.obj -fopenmp -w

Error using _msvccompiler>compile (line 403)

Python Error: CompileError: command 'C:\\Program Files (x86)\\Microsoft Visual

Studio\\2019\\Community\\VC\\Tools\\MSVC\\14.23.28105\\bin\\HostX86\\x64\\cl.exe' failed with exit code 2

Error in build_ext>build_extension (line 529)

Error in build_ext>_build_extensions_serial (line 474)

Error in build_ext>build_extensions (line 449)

Error in old_build_ext>build_extensions (line 195)

Error in builder>build_extensions (line 149)

Error in build_ext>run (line 340)

Error in old_build_ext>run (line 186)

Error in dist>run_command (line 985)

Error in dist>run_commands (line 966)

Error in builder>_build_impl (line 249)

Error in builder>build (line 226)

Error in builder>load_cython_ext (line 110)

Error in builder><module> (line 504)

Error in __init__><module> (line 2)

Error in robot_env><module> (line 14)

Error in fetch_env><module> (line 3)

Error in __init__><module> (line 1)

Error in <frozen importlib>_call_with_frames_removed (line 228)

Error in <frozen importlib>exec_module (line 850)

Error in <frozen importlib>_load_unlocked (line 680)

Error in <frozen importlib>_find_and_load_unlocked (line 986)

Error in <frozen importlib>_find_and_load (line 1007)

Error in <frozen importlib>_gcd_import (line 1030)

Error in __init__>import_module (line 127)

Error in registration>load (line 55)

Error in registration>make (line 139)

Error in registration>make (line 520)

Error in registration>make (line 676)

>>

I have googled for this problem, and although it seems common, no thread gives a proper solution, and even less taking MATLAB into account.

Could anyone give a possible solution for this issue.

Thank you all very much in advance.

Answer 1

[Eric Delgado]

Hi @Alberto Tellaeche, I was dealing with a similar issue - numpy was the lib that was not running. The solution was create a new env using conda.

Anaconda prompt (or similar):

conda create -n numpy python=3.9 numpy -c conda-forge -y

Matlab (pointer to the python.exe of the new env):

pyenv('Version', 'C:\Users\eric\anaconda3\envs\numpy\python.exe')