Is it possible to display a MATLAB plot in python?

I found one example with the Compiler SDK for Java here, but none for a python application.

I tried to package the following code to a python module via the Librabry Compiler (Compiler SDK):

function drawplot(x,y)
plot(x,y);

I installed the module and then tried to call the function in Python:

import PlotDrawer
myPlotter = PlotDrawer.initialize()
myPlotter = PlotDrawer.drawplot(5,5)

The import works, but I get this error:

AttributeError: module 'PlotDrawer' has no attribute 'drawplot'

When I don't use plots like in this example I don't get any errors and it works just fine. My guess is that MATLAB Library Compiler ignores functions with graphical functions in it. Is it even possible to display a MATLAB Plot in Python via the Compiler SDK?

I have the code written already in MATLAB and want to create a GUI in Python (for more flexibility and better, professional appearance). Any other approaches?

Thanks in Advance!

Answer 1

[Kojiro Saito]

There are two things I found in your codes.

1. After initialization, you need to use the same variable name ( myPlotter) in your python script.
2. The number of output from drawplot function is 0, so you need to specify nargout=0 in the function call.

Here's the Python code which will display MATLAB figure.

import PlotDrawer
myPlotter = PlotDrawer.initialize()
myPlotter.drawplot(5, 5, nargout=0)

Also, if want to input arrays, matlab.double is available by importing matlab.

The following python code will dipslay 2D line plot.

import PlotDrawer
import matlab
myPlotter = PlotDrawer.initialize()
x = matlab.double([1,2,3,4,5])
y = matlab.double([1,2,3,4,5])
myPlotter.drawplot(x, y, nargout=0)

Also, there's a user's guide for MATLAB Compiler SDK for Python, which might help you.

MATLAB Compiler SDK Python User's Guide (PDF)

[Oemer Aran]

Thank you that worked. Kind of embarrassing that I overwrote the variable "myPlotter". The nargout=0 was really helpful tho.

[Tianya Duan]

Kojiro Saito, hi, when I use python call the funtion plot, the figure only exists few seconds, why does have this phenomenon occur? How could I change or add something? Thank you very much.

AddTset.m

function c = AddTest(a,b)
   c = a + b;
   figure(1)
   plot(a,c,'DisplayName','test');
   %pause(30);
end

pyCallMat.py

import matlab.engine

if __name__ == '__main__':
    eng = matlab.engine.start_matlab()#可以为所欲为的调用matlab内置函数
    a = eng.AddTest(1.0,2.0) #引用自写的脚本
    print(a)
    b = eng.sqrt(4.) #引用matlab内置函数
    eng.figure(3.0)
    eng.plot(a, b, nargout=0)

    print(b)

[Kushal Malhotra]

Hey @Tianya Duan, you could try this

eng.hold("on",nargout=0)

Initialize this before you initialize the plot. If this doesn't work then I would say, this phenomenon occur because the python program terminates. So if the above line doesn't work then sleep your python program for a while using this

time.sleep(1000)

Add it at the very end of your python program.

[Bardo]

Hi,

may I ask where to find the PlotDrawer() routine?

Thx