How to resolve error calling Python from MATLAB?

I have both MATLAB 2022a and 2022b on the same machine. MATLAB 2022a always called python without any issue. But now I installed 2022b and Python doesn't work. How to fix this error? Thanks.

Error using __init__

Python Error: TclError: Can't find a usable init.tcl in the following

directories:

C:/Users/kkkAppData/Local/Programs/Python/Python39/lib/tcl8.6

{C:/Program Files/MATLAB/R2022b/bin/lib/tcl8.6} {C:/Program

Files/MATLAB/R2022b/lib/tcl8.6} {C:/Program

Files/MATLAB/R2022b/bin/library} {C:/Program

Files/MATLAB/R2022b/library} {C:/Program

Files/MATLAB/R2022b/tcl8.6.9/library} {C:/Program

Files/MATLAB/tcl8.6.9/library}

This probably means that Tcl wasn't installed properly.

Answer 1

[Shoaib iqbal]

Looking at the Python source code Modules\_tkinter.c, TCL uses hard coded location of tcl_library_path to find its initialization files which doesn't work when Python is loaded by MATLAB.

Here is an workaround:

>> setenv('TCL_LIBRARY', 'C:\Users\sji\AppData\Local\Programs\Python\Python38\tcl\tcl8.6')

>> setenv('TK_LIBRARY', 'C:\Users\sji\AppData\Local\Programs\Python\Python38\tcl\tk8.6')

>> py.tkinter.Tk

Run these commands every time you run MATLAB. Alternatively, place the commands in a MATLAB startup script.

[Nadatimuj]

Thanks for the reply. I applied those three lines and now I am getting this error,

Error using __init__

Python Error: IndexError: list index out of range

setenv('TCL_LIBRARY', 'C:\Users\sji\AppData\Local\Programs\Python\Python38\tcl\tcl8.6')
setenv('TK_LIBRARY', 'C:\Users\sji\AppData\Local\Programs\Python\Python38\tcl\tk8.6')
py.tkinter.Tk
target =double(pyrunfile("getPegasusAdjacency.py","JJ",size= size_pegasus)); %PYTHON Version

[Nadatimuj]

@Shoaib iqbal is there no solution to this? A version that works in 2022a is broken in 2022b is very unfortunate. Can we report a bug so that they fix in 2023a? Thanks.

[Siyu]

For 2022b, there is another workaround, this error was resolved for some users by using the following code where "pyenv("ExecutionMode","OutOfProcess")" is used:

>> terminate(pyenv) % Adjusted: in case there is already a process running, we should stop it

>> pyStr = pyenv("ExecutionMode","OutOfProcess"); % Adjusted

>> pyTCL = fullfile(pyStr.Home, 'tcl', 'tcl8.6');

>> pyTK = fullfile(pyStr.Home, 'tcl', 'tk8.6');

>> setenv('TCL_LIBRARY', pyTCL);

>> setenv('TK_LIBRARY', pyTK);

The 'OutOfProcess' input in "pyenv" starts a separate process and is used for safe execution of Python scripts and libraries. Also, "terminate(pyenv)" was added to stop any "pyenv" processes which may be running. More can be read about this here: https://www.mathworks.com/help/matlab/ref/pyenv.html?searchHighlight=pyenv&s_tid=srchtitle_pyenv_1#mw_33379b1a-e442-4992-8a9a-d2e7646953a4.