Run matlab script in python - error

Question

I have a problem with running matlab code in python. When I run my easy code, I have this information in matlab console:

Undefined function or variable 'messenger'.

Error in matlabserver (line 7) messenger('init', socket_address);

Matlab code:

%% MATLAB
function lol = yourfunc(args)
    arg1 = args.arg1;
    arg2 = args.arg2;
    lol = arg1 + arg2;
end

Python code:

from pymatbridge import Matlab
mlab = Matlab()
mlab.start()
res = mlab.run('...path\yourfunc.m', {'arg1': 3, 'arg2': 5})

print(res['result'])

Looking at this github thread @quic0 : I had the same problem on Windows 10. The problem is that Matlab cannot find the mex file messenger.mexw64. It connects if you copy the mex file from pymatbridge\messenger\mexw64 to pymatbridge\matlab in your Python package folder. It seems that all other issues relate to re-compiling the messenger mex file specifically for your system — WoodyDev
– WoodyDev, Commented Feb 2, 2018 at 12:20
Ok, now it's works, but i have a problem, when i print 'res' in pycharm, i have this "{'result': '', 'success': False, 'content': {'stdout': 'Too many input arguments.'}}" — Dzejkob28
– Dzejkob28, Commented Feb 2, 2018 at 12:51
Dzejkob, congrats on your first answered question and welcome to the site. Please have a read at the site's guidlines on how to ask questions. Specifically, avoid lumping a second question on the original one (especially since the two are essentially completely unrelated, and the second question no longer corresponds to the question body), but prefer to ask such questions as separate standalone questions. Also, consider using more informative titles that would help future users googling for the same error. "Matlab error" is incredibly uninformative. — Tasos Papastylianou
– Tasos Papastylianou, Commented Feb 2, 2018 at 14:17

WoodyDev · Accepted Answer · 2018-02-02 14:10:45Z

So as a dedicated answer to the OP question (initially it was necessary to re-compile the mex file messenger.mexw64 for windows 10 [see the original post comments]):

Ok, now it's works, but i have a problem, when i print 'res' in pycharm, i have this "{'result': '', 'success': False, 'content': {'stdout': 'Too many input arguments.'}}"

In your matlab function you stated only one argument:

function lol = yourfunc(args)

But when you call it in python you are calling it with two input arguments (arg1 & arg2):

res = mlab.run('...path\yourfunc.m', {'arg1': 3, 'arg2': 5})

In the matlab function input you are assuming it is a data structure with at least the two fields arg1 & arg2; you are referencing these variables from the structure when you call

args.arg1
args.arg2

As I am not sure if you can pass a data structure this technique (as a JSON style string input from a python function) I would propose changing the input arguments to the Matlab function to either:

Change your function to support two arguments like how you are calling it from python:

%% MATLAB
function lol = yourfunc(input1,input2)
    arg1 = input1;
    arg2 = input2;
    lol = arg1 + arg2;
end

# PYTHON (just to be clear)
from pymatbridge import Matlab
mlab = Matlab()
mlab.start()
res = mlab.run('...path\yourfunc.m', {'input1': 3, 'input2': 5})

print(res['result'])

Or if you want to handle an infinite number of inputs (using varargin):

%% MATLAB 
function lol = yourfunc(varargin)
    arg1 = varargin{1};
    arg2 = varargin{2};
    lol = arg1 + arg2;
end

# PYTHON (just to be clear)
from pymatbridge import Matlab
mlab = Matlab()
mlab.start()
res = mlab.run('...path\yourfunc.m', {'input1': 3, 'input2': 5})

print(res['result'])

This should then remove the error message about too many input arguments and run successfully :)

Collectives™ on Stack Overflow

Run matlab script in python - error

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related