Run Matlab Command Line Operations from Python

1 Run Matlab Functions

Go to the RMD, PDF, or HTML version of this file. Go back to Python Code Examples Repository (bookdown site) or the pyfan Package (API).

1.1 Generate A template Matlab Script

Generate an example matlab script file with parameter x.

# Example Matlab Function
stf_m_contents = """\
a = x + 1
b = 10*x\
"""
# Print
print(stf_m_contents)
# Open new file

## a = x + 1
## b = 10*x

fl_m_contents = open("_m/fs_test.m", 'w')
# Write to File
fl_m_contents.write(stf_m_contents)
# print

## 18

fl_m_contents.close()

1.2 Run the Matlab Function from Commandline

• run matlab function from command line
• Retrieving the output of subprocess.call
• https://www.mathworks.com/help/matlab/ref/matlabwindows.html

First, check where matlab is installed:

import subprocess
cmd_popen = subprocess.Popen(["where", "matlab"],
                             stdin=subprocess.PIPE,
                             stdout=subprocess.PIPE,
                             stderr=subprocess.PIPE)
output, err = cmd_popen.communicate()
print(output.decode('utf-8'))

## G:\ProgramData\MATLAB\R2020b\bin\matlab.exe

Second, run the matlab file, first definet he parameter x:

import os
# print and set directory
print(os.getcwd())

## G:\repos\Py4Econ\support\system

os.chdir('_m')
print(os.getcwd())
# run matlab script saved prior
# running command line: matlab -batch "fs_test; exit"

## G:\repos\Py4Econ\support\system\_m

cmd_popen = subprocess.Popen(["matlab", "-batch", "\"x=1; fs_test; exit\""],
                             stdin=subprocess.PIPE,
                             stdout=subprocess.PIPE,
                             stderr=subprocess.PIPE)
output, err = cmd_popen.communicate()
print(output.decode('utf-8'))

## 
## a =
## 
##      2
## 
## 
## b =
## 
##     10
## 

Third, run the function again, but with x=3:

os.chdir('_m')
print(os.getcwd())

## G:\repos\Py4Econ\support\system\_m

print(subprocess.Popen(["matlab", "-batch", "\"x=5; fs_test; exit\""],
                       stdin=subprocess.PIPE,
                       stdout=subprocess.PIPE,
                       stderr=subprocess.PIPE).communicate()[0].decode('utf-8'))

## 
## a =
## 
##      6
## 
## 
## b =
## 
##     50
##