[Matlab in python] Does matlab engine supports a .m file whose input is a function handle?

Question

Sungha Cho 2019-6-21

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/468232-matlab-in-python-does-matlab-engine-supports-a-m-file-whose-input-is-a-function-handle

回答： Mike Croucher 2024-1-24

Hi all, I want to use matlab.engine to run .m file.

To make an easy explanation, lets assume I have my_fun.m file with

function res = my_fun(f)
res = f(0)
end

Here f is (or could be) a function hadle like

f = @(x) sin(x)

Now to run this file in python, I should run

import matlab.engine
eng = matlab.engine.start_matlab()
eng.my_fun(nargout=1)

Of course, this code returns an 'lack-of-input' error. How do I input a function handle f into the third line of the code?

Moreover, I ultimately want to do the following:

Is there a way to input a 'python function' like

import numpy as np
def f(x):
    return np.sin(x)

?

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Filippo 2024-1-23

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Answer 1

Mike Croucher 2024-1-24

0
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/468232-matlab-in-python-does-matlab-engine-supports-a-m-file-whose-input-is-a-function-handle#answer_1396781

在 MATLAB Online 中打开

Unfortunately, the MATLAB Engine for python does not support passing Python functions to MATLAB. Running the following in Python:

import matlab.engine
eng = matlab.engine.start_matlab()
import numpy as np
def f(x):
    return np.sin(x)
eng.my_fun(f)

gives

---------------------------------------------------------------------------TypeError Traceback (most recent call last) Cell In[11], line 1----> 1 eng.my_fun(f)File ~\AppData\Local\Programs\Python\Python310\lib\site-packages\matlab\engine\matlabengine.py:64, in MatlabFunc.__call__(self, *args, **kwargs) 61 _stderr_info = '{0}.{1}'.format(_stderr.__class__.__module__, _stderr.__class__.__name__); 62 raise TypeError(pythonengine.getMessage('StderrMustBeStringIO', _sIO_info, _stderr_info)) ---> 64 future = pythonengine.evaluateFunction(self._engine()._matlab, 65 self._name, nargs,args, 66 out=_stdout, err=_stderr) 67 if background: 68 return FutureResult(self._engine(), future, nargs, _stdout, _stderr, feval=True)

TypeError: unsupported Python data type: function

So, we are unable to get a Python function from Python into MATLAB. Even if we could, we'd need to do something different in my_fun.m I think.

I'll raise this as a feature request with development. Can I ask why you need to do this please? Having a solid application can help set priorities.