Return multiple variables from MATLAB to Python

Hello,

I am using MATLAB for data processing and Python for Keras + TensorFlow. I must say that I am new to Python, but I am confortable coding in MATLAB.

I have a function in MATLAB which return 3 matrices and has the following signature:

 function [noisyMFCC, targetIBM, targetIRM] = getTestingData(sampleTesting)

While in Python I wrote this:

import matlab.engine

class DataProcessor:
    __matlabEngine = matlab.engine.start_matlab()

      def getTestingData(self, isSampleTesting):
          return DataProcessor.__matlabEngine.getTestingData(isSampleTesting)

      def getTrainingData(self, isSampleTesting):
          return DataProcessor.__matlabEngine.getTrainingData(isSampleTesting)

dp = DataProcessor()
a, b, c = dp.getTestingData(True)
print(a)

And I receive the following error:

 ValueError: too many values to unpack (expected 3)

So I assume that MATLAB engine returns some kind of structure or just one of the three returns.

I also tried a solution given by here :

 a, b, c = dp.getTestingData(True, nargout=3)

And it returns (as expected):

 TypeError: getTestingData() got an unexpected keyword argument 'nargout'

Apperently if I am to use the following line of code:

 c = dp.getTestingData(True, nargout=3)

c is the first return element of the function, how do I get the rest?

Thank you for your time!

Answer 1

[Bo Li]

Apparently, "nargout" is a keyword argument defined for Python Engine. "dp.getTestingData(True, nargout=3)" does not work because the member function "getTestingData" of "class DataProcessor" does not accept this keyword argument. You can specify the number of output when calling Python Engine:

 def getTestingData(self, isSampleTesting):
    return DataProcessor.__matlabEngine.getTestingData(isSampleTesting, nargout=3)