How to call a matlab plot function from python with arguments?

Hi all,

I am trying to create 3D graphs in python and cannot use matplotlib, as I need to be able to plot with log scales. This led me to controlling matlab via python. I am trying to create a function to plot a 3d graph. When I call my function in python, I get an error saying "not enough input arguments". Here is my matlab code, python code, and screenshot of error. Can anyone point me in the right direction?

matlab, tplot.m

function tplot(X, Y, Z)
figure
plot3(X, Y, Z)
end

python

import matlab.engine

eng = matlab.engine.start_matlab()

X = matlab.double([1, 2, 3, 4, 5])
Y = matlab.double([5, 6, 7, 8, 5])
Z = matlab.double([9, 10, 11, 12, 13])

eng.tplot(X, Y, Z, nargout=0)

eng.close()

and lastly my error:

Answer 1

[Sai Sri Harsha Vallabhuni]

Instead of

eng.tplot(X, Y, Z, nargout=0)

Try this

eng.run("\path\to\tplot.m\file", X, Y, Z, nargout = 0)

Hope this helps.

[Nicholas Clavette]

Hi Sai,

Thanks for your response. That did not work unfortunately. I've graduated to using Matlab Library Compiler and Matlab runtime to create my plot. I get no errors, but the plot only displays for a millisecond. Any advice?

import matlab
import tPlotPkg


X = matlab.double([1, 2, 3, 4, 5])
Y = matlab.double([6, 7, 8, 9, 10])
Z = matlab.double([1, 2, 3, 4, 5])

myPlot = tPlotPkg.initialize()

myPlot.tplot(X, Y, Z, nargout=0)

Again, code compiles fine. I see a window flash on my screen (I am assuming this is my plot)? Then the program ends. Is there a way to stall while the window is open?

[Kushal Malhotra]

Hello @Nicholas Clavette

Try a matlab function eng.hold("on",nargout=0). If that doesn't work then I would suggest it usually happens because the python script is terminated. So at the last line of your python program add time.sleep(1000). This won't terminated the current pthon program and allow you to view those figures for the amount of time mentioned in .sleep() method. The time is in seconds mentioned above. :)