How to create a python 3 class to start MATLAB and keep it running

I'm using matlab 2017b and python 3 on windows 10. I want to create a class that can start the matlab and keep it open. However, matlab closes right after I finished the python script. Here is the code:

import matlab.engine
class Test:
    def __init__(self):
        self.eng = matlab.engine.start_matlab("-desktop")
        
if __name__ == "__main__":
    Test()
    

I can open the matlab in python console with the "start_matlab" command, but with this class I will keep failing to keep it open.

Anyone know how I could make this work?

Thanks

Answer 1

[Kojiro Saito]

How about using matlab.engine.shareEngine?

test.py

import os
class Test:
    def __init__(self):
        self.eng = os.system("matlab -r \"matlab.engine.shareEngine('myMatlabEngine')\"")
if __name__ == "__main__":
    Test()
    

test2.py

import matlab.engine
eng = matlab.engine.connect_matlab('myMatlabEngine')
print(eng.sqrt(4.0))

Usage:

Open a terminal

python test.py

This keeps MATLAB session running.

Then, open another terminal and call test2.py.

python test2.py

[tamashika]

Thanks for the solution, but I think your test.py will do the trick by itself. Even after I closed the console which ran test.py, matlab would still stay open. Is there something I miss?

[tamashika]

Hey Kojiro, I think I know what I missed. If we use matlab engine to start matlab, matlab will close when the script close since the variable will be cleared. You are proposing to use os.system to open a shared session of matlab, and connect to that matlab using matlab engine everytime I want to do the calculation. I think that's brilliant. I can't think of any other better way. Thanks again for the help!

[Kojiro Saito]

Hi Andy, yes, as document explains, "If you exit Python with an engine still running, then Python automatically stops the engine and its MATLAB process.", so matlab.engine.start_matlab cannot keep MATLAB engine running if the Python is exited. That's why I've recommended to use matlab.engine.shareEngine. But Python's matlab.engine does not have shareEngine, so I proposed to use os.system command instead.

[tamashika]

Could you take a look at the other question I have related to your answer?

https://www.mathworks.com/matlabcentral/answers/545585-can-t-import-os-and-matlab-engine-in-the-header#question_545585