returning values from matlab to python (as a dictionary?)

Question

I am using the matlab engine for python. My goal is to pass some info to my matlab script from python, and then store the result. I was able to do this if I created a matlab array of all the values I wanted, but I would really like a dictionary (so I can remember what value goes with what variable or if I change my matlab script in the future). This is what I've tried:

MATLAB function:

function out = mymatlabfunc(x,y)
    # compute stuff
    out = py.dict('interesting variable 1', x_out, 'interesting variable 2', y_out, ...);

and in python:

eng = matlab.engine.start_matlab()
xdata, ydata = matlab.double(x), matlab.double(y)
resultdict = eng.mymatlabfunc(xdata,ydata)

Unfortunately this doesn't return my dictionary, but a matlab.object that I don't know what to do with. Is it possible to return my dictionary, or should I simply return the numbers from matlab and make my dictionary in python?

From m-side it's just a "Python Object" because matlab does not support dictionaries. Just call methods like `get` on it to get whantever you want. — Daniel, Jun 21 '15 at 08:33
@Daniel I get an error saying that matlab.object has no attribute 'get'. Python sees this as a matlab object still, not a dictionary. — qRTPCR, Jun 21 '15 at 17:33

score 0 · Answer 1 · answered Jun 21 '15 at 13:46

0

You could do a dir (resultdir) in order to know what methods are available.

answered Jun 21 '15 at 13:46

Cristea Bogdan

116
1
11

The only method I see available is size and stuff like '__class__' and '__getattribute__'. I can get the length of it (length 1), but it's a matlab object as far as python is concerned so I can't do normal dictionary operations with it. – qRTPCR Jun 21 '15 at 17:36

score 0 · Accepted Answer · answered Jun 22 '15 at 16:03

I figured it out from the mathworks website. Simply make a matlab structure for the return value of your script and python will see it as a dictionary. So my matlab code is now:

function out = mymatlabfunc(x,y)
    # compute stuff
    out = struct('interesting variable 1', x_out, 'interesting variable 2', y_out, ...);

returning values from matlab to python (as a dictionary?)

2 Answers2