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error output from python matlab engine

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Jeremy Rutman
Jeremy Rutman on 13 Jan 2016
Commented: Jeremy Rutman on 27 Jan 2016
I'd like to get better debug info than the 'matlab function cannot be evaluated' that I currently see from a complex matlab function being run from python using the python matlab engine. Is there some way to pipe extra matlab debug output to a file and/or get more info ?
  2 Comments
Stephen23
Stephen23 on 13 Jan 2016
Edited: Stephen23 on 13 Jan 2016
The documentation
states that you should get the whole MATLAB error message from the Python Engine: "When a MATLAB® function raises an error, the MATLAB Engine for Python® stops the function and catches the exception raised by MATLAB. The engine copies the error message to a new Python exception. The engine raises the Python exception."
That page gives several examples of this.
What other information would you like?
Jeremy Rutman
Jeremy Rutman on 27 Jan 2016
pretty much anything beyond 'matlab function cannot be evaluated' would be great - i've been using
out = StringIO.StringIO()
err = StringIO.StringIO()
retvals = matlab_engine.myfunc(image_filename, nargout=3,stdout=out,stderr=err)
outstring = out.getvalue()
errstring = err.getvalue()
logging.debug('ml output:'+str(outstring)+'\n')
logging.debug('ml err output:'+str(errstring)+'\n')

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Answers (1)

Robert Snoeberger
Robert Snoeberger on 15 Jan 2016
You could get the last uncaught exception [1] and then call getReport [2] to get the error message for that exception.
Example
>>> import matlab.engine
>>> eng = matlab.engine.start_matlab()
>>>
>>> # Do something that throws an exception...
>>>
>>> eng.eval('exception = MException.last;', nargout=0)
>>> eng.eval('getReport(exception)')
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