How to run a python code on simulink?

I am trying do some image processing and have codes written in python. I am trying to make it run on matlab/simulink. Is there a simulink block that can run python codes? Something like I can give an input to the block, it will run the python code and give the output.

[faazila fathima]

sir i tried calling python from matlab, but am unable to do. pls help am getting this error 'Caused by:

Undefined function 'py.te2.c2' for input arguments of type 'double'.

Answer 1

[Nick Choi]

You could try using a MATLAB function block that contains MATLAB code to call the Python code.

This documentation link provides an example of how to integrate a MATLAB function block into a Simulink model,

https://www.mathworks.com/help/simulink/ug/example-calculating-statistical-mean-and-standard-deviation.html

and this documentation link contains useful information on how to use Python code with MATLAB: https://www.mathworks.com/help/matlab/getting-started-with-python.html

One thing to note is that not all MATLAB functionalities will be supported for code generation so you may need to use 'coder.extrinsic' in the MATLAB function block. Additional information on 'coder.extrinsic' can be found here:

https://www.mathworks.com/help/simulink/slref/coder.extrinsic.html

[Nitharshini Sivakumar]

Thanks a lot. That really helps.

[Bikash Sah]

Can you please share a sample model that links Python with Simulink. I tried multiple times, but I was not able to.

[Henry Kotze]

What you need to do is: Create a matlab function (Not a simulink Matlab Function block) where you call your Python script. Remember to convert them to the correct types and ensure that the matlab function is able to see the python script.

Then from simulink you use the Interpreted Matlab Function block in simulink to call your function.

[Elif Ecem Bas]

Does this work in Simulink Real-Time machine? If not do you suggest any other solutions?

[Lode De Herdt]

It probably won't work in a real-time machine because this function is not supported for code generation. A Simulink model that uses this cannot be translated to C code which is usually what is needed to run it on a real-time machine.

[Sean de Wolski]

It is possible to call python code inside of a C S-Function. It's fairly involved and requires connecting a lot of pipes. Please contact if this interests you or ask a new question.

[PRANESH KUMAR]

I want to run python code which is inside raspberry pi and simulink on pc.how to go about it

Answer 2

[Lode De Herdt]

Yes, this is possible to do. A very simple example of Python code running in Simulink using the MATLAB Function block:

The MATLAB Function block refers to this code:

function out = RunPython(in1, in2)
    out = 0; % Has to be preassigned, otherwise Simulink throws an error
    coder.extrinsic('py.Example.test') % Python functions have to be run extrinsically, meaning no C code generated
    out = py.Example.test(in1,in2);
end

And the Python code (in Example.py file) is:

def test(in1,in2):
    out = in1+in2
    return out

[Moein Sabounchi]

I tried this, but I repeatedly receive the error that the function specified in "coder.extrinsic" AKA python function is undefined. I was wondering if you have faced this issue and what is the solution?

Thanks

[Lode De Herdt]

Make sure Python commands can run in MATLAB before trying to run it in Simulink. If you run pyenv (or pyversion if you have an older release) in the MATLAB command window, does it return the Python version you're wanting to use? If not, check the documentation on how to set MATLAB's Python interpreter.

[Sean de Wolski]

I find it's better to package all of the python functionality into another MATLAB function and then flag that function as extrinsic.

function out = MyBlock(in1, in2)
    out = 0; % Has to be preassigned, otherwise Simulink throws an error
    coder.extrinsic('usePython') % Python functions have to be run extrinsically, meaning no C code generated
    out = usePython(in1, in2);
end

Then

function out = usePython(in1, in2)
    out = py.math.remainder(in1, in2);
end

This was everything you do with python is outside of the scope of code generation rathen than just one method.

[Grace Connors]

Is it possible to add back in the python functions once the code has been generated? What if they are integral to running on a real-time machine? (As in, you're using ML predictions from python because MATLAB doesn't support the latest keras update).

[Sean de Wolski]

Grace, that warrants it's own question. I suspect you'd need to write a C function to call Python and then use coder.ceval inside the MATLAB function block but there may be a more efficient way. have you looked at the keras importers for MATLAB which may allow you to import the model and generate code from it?

[Quan minhquanccna]

Thank you for the example, it works well for me. However, when I change the python function from (out = in1+in2) to (out = in1*in2) for example. I need to close and call Matlab again from Anaconda prompt. Otherwise, MATLAB still understands that is "add" in the code. Can you help me with this?

[Sean de Wolski]

Quan, please ask this as a new question next time. You need to clear and reload the module:

function reloadLib(libname)
% Reload the Python library 
% Necessary if changes are made to .py code

clear classes %#ok<CLCLS>
m = py.importlib.import_module(libname);
py.importlib.reload(m);

[Quan minhquanccna]

Thank you for your support, Sean.

[K G V Kalyan Sreenivas Kumar]

Hello Lode De Herdt

I have python function where its output is python list how do I get that output?

[Sean de Wolski]

K G V,

You could convert the py.list to a cell array c = cell(list) but even that doesn't make much sense to propagate as a Simulink signal. You'll probably want to grab the elements inside of it and determine what to do with them. Can you give more insight into the use case? And probably worth it to create a new question.

[faazila fathima]

sir, i tried exactly what u did.

But when i call the python code in matlab command window, am getting this error. what does this error mean?

Unrecognized function or variable 'in1'.

Answer 3

[Weiwu Li]

You can either use a MATLAB function block or a MATLAB System block to bring Python code into Simulink.

You can refer to the Simulink doc for a simple example:

https://www.mathworks.com/help/simulink/ug/python_simulink_example.html#responsive_offcanvas

For a more complex / realistic example (using Python for human detection), you can refer to this file exchange submission:

https://www.mathworks.com/matlabcentral/fileexchange/100501-integrate_python_code_with_simulink

[Bartosz Soltowski]

Hi,

I managed to integrate Python functions into my Simulink code but I am facing problems while deploying the system into external hardware (Raspberry PI). The Matlab coder does not recognise extrinsic functions. Is there any solution to that problem?

[Sean de Wolski]

The solution is to use a C-S function and a custom TLC that tells the MATLAB code generator how to generate C code that can communicate with Python. As I said above, this is doable but really hard and involved. It's like me in English trying to tell someone who speaks Korean how to communicate with someone who speaks Swahili.

In general, it would be far better to take the python things you're doing right now in coder.extrinsic and rewrite them in Simulink/MATLAB/C/C++. Can you describe what the python piece is doing right now and what the data I/O from the MATLAB function to it are?