Accessing a running MATLAB object from Python

I have a MATLAB class that runs some hardware. I use it as an API by other code in order to build small MATLAB applications. I have some users who want some of the functionality available in Python. It's quite a lot of work to redo everything in Python (there is also a GUI) so I'm looking into the possibility of making the API available in Python somehow.

Here is what I'm looking to do: I want to instantiate my class in MATLAB and have the user set everything up. I'm then wondering if it's possible for Python to somehow access this workspace and run methods of the instantiated object. It seem unlclear me, though, if the if matlab.engine can do that. Does anyone know?

If that is not possible, what might be a good alternative? Maybe through TCP IP if I write a suitable server/client system? I've not done that before, though, and don't know where to start.

Any other options?

Answer 1

[Vijay]

Hello @Rob Campbell

Yes, you can connect from python to a running instance of MATLAB and execute commands and access workspace variables.

Follow below steps

1. First, convert your MATLAB session to a shared session by executing the below command in MATLAB

 matlab.engine.shareEngine

2. connect to the shared MATLAB session by connect_matlab function from python API

Example:

import matlab.engine 
eng = matlab.engine.connect_matlab() 
eng.sqrt(4.0)

You can use eng.eval function to execute any commands in MATLAB.

Please refer to the following link for more information Connect Python to Running MATLAB Session - MATLAB & Simulink - MathWorks India.

Hope that helps!

[Rob Campbell]

I tried this and can indeed access the workspace of a running session. What seems to work for me (at least with a toy example) is:

• I create an instance of a class, let's call it myS, in MATLAB.
• I see it's there in Python with eng.who()
• Then I pull the object into Python: localS = eng.workspace["myS"]
• To run a method the call is a little weird, but it works: eng.myMethod(localS,INPUT_ARG,nargout=0)