why does Matlab return ' expression to the left of the equals sign is not a valid target'

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Charles
Charles on 5 Sep 2017
I am using MATLAB 2017a and Python 3.6 I am trying to call a Python script from within the MATLAB window and assign the returned variables to the MATLAB workspace.
I am told by MATLAB help desk that MATLAB does support this version of Python, contrary to what their website says. I have copied my Python folder to my MATLAB pathway as follows:
insert(py.sys.path,int32(0), '/Users/....../Oandafx');
I now attempt to execute the following command in the MATLAB command window
N = py.oandafx.get_history('EUR_USD', granularity='D', prices='BA', count=5)
I get the following error. Can you tell me where I am going wrong?
Error: The expression to the left of the equals sign is not a valid target for an assignment.

Answers (2)

Robert Snoeberger
Robert Snoeberger on 6 Sep 2017
MATLAB doesn't support keyword arguments [1]. To pass keyword argument to Python, use pyargs [2].
Example:
N = py.oandafx.get_history('EUR_USD', pyargs('granularity','D','prices','BA','count',5))
  1. https://docs.python.org/2/tutorial/controlflow.html#keyword-arguments
  2. https://www.mathworks.com/help/matlab/ref/pyargs.html

Walter Roberson
Walter Roberson on 5 Sep 2017
It is not legal to have '=' inside MATLAB expressions. You probably need to do a bunch of quoting.
  2 Comments
James Tursa
James Tursa on 5 Sep 2017
E.g., you can't have this as a literal argument:
count=5
You might have to quote the whole thing like this
'count=5'
Same for the other arguments with equal signs. It will depend on what form py.oandafx.get_history accepts.

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