Matlab requires restart before changes in Python code changes are applied

Background:

I am running Matlab 2020a and Python 3.8 on Win 10. I am launching Matlab from an Anaconda prompt in the mne environment (https://mne.tools/stable/index.html).

I am calling a Python function using the standard syntax - ex: r = py.test.score(X,y).

The Issue:

I make changes to the Python code, save, and runfile which are immediately available in my Python ide (Spyder), but Matlab does run the latest version of the Python function. I have to restart Matlab - using the Anaconda prompt in the mne environment - each time I make a change to my Python code. Upon restart, the updated Python code is used by Matlab.

I update the current Python path prior to calling my Python function using:

if count(py.sys.path,'')==0
    insert(py.sys.path,int32(0),'');
end

I have tested this with a basic "Hello World" type Python function and this is my experience.

I am not sure how to further troubleshoot this issue.

Is there something I may be doing incorrectly?

Thanks in advance,

Daniel

[Stijn Haenen]

Is there an .asv file of the python script saved in your working folder. The .asv files are used as backup while matlab is running. Maybe you should change the .asv files of the python script.

[Daniel Stolzberg]

Thank you for your suggestion, Stijn.

I don't see any files with the .asv extension in my working folder.

There is a folder called __pycache__ which has a file called test.cpython-38.pyc in it. This seems to be a compiled python file.

Any other suggestions? It is quite inconvenient to restart Matlab each time I make a change to the Python script.

Answer 1

[Sean de Wolski]

Try this

clear classes
m = py.importlib.import_module('yourlib');
py.importlib.reload(m);

[Daniel Stolzberg]

Thanks for this solution, Sean!

Note to someone reading this in the future, clear classes will, of course, clear all workspace variables as well.

Thank you!

[Ronan Fleming]

https://nl.mathworks.com/help/releases/R2021a/matlab/matlab_external/out-of-process-execution-of-python-functionality.html

Answer 2

[Chen]

Sean's answer will not work without wrapping a function around it.

Apparently, it's a known bug

How can I clear specific Python classes/modules from memory without using "clear classes" - MATLAB Answers - MATLAB Central (mathworks.com)

function reloadPy()
    warning('off','MATLAB:ClassInstanceExists')
    clear classes
    mod = py.importlib.import_module('mat');
    py.importlib.reload(mod);
end

[Sean de Wolski]

I might suggest modifying the warning part to this to restore state after.

s = warning('off','MATLAB:ClassInstanceExists');
restorer = onCleanup(@()warning(s));

[Akshay Jajoo]

I am getting the following error: Unable to resolve the name py.importlib.reload.

Answer 3

[MONIKA]

function reloadPy() warning('off','MATLAB:ClassInstanceExists') clear classes mod = py.importlib.import_module('mat'); py.importlib.reload(mod);

Answer 4

[MONIKA]

function reloadPy() warning('off','MATLAB:ClassInstanceExists') clear classes mod = py.importlib.import_module('mat'); py.importlib.reload(mod);