Pyrun - error when running python script

Hi,

I am trying to run a python script from MATLAB. The script aims to setup a websocket server.

>> pyrun('webs_server.py')
Error using <string>><module> (line 1)
Python Error: NameError: name 'webs_server' is not defined

Python script runs fine when run under Conda.

My pyenv is following:

ans = 

PythonEnvironment with properties:

Version: "3.9"
Executable: "C:\Users\kowal\AppData\Local\Programs\Python\Python39\python.EXE"
Library: "C:\Users\kowal\AppData\Local\Programs\Python\Python39\python39.dll"
Home: "C:\Users\kowal\AppData\Local\Programs\Python\Python39"
Status: Loaded
ExecutionMode: InProcess
ProcessID: "15984"
ProcessName: "MATLAB"

The directory with the script is in the path. What could be the possible issue?

Answer 1

[Bala Tripura Bodapati]

Hi Marcin

It is my understanding that you would like to execute Python script from MATLAB and are encountering an error while using the 'pyrun' function.

The 'pyrun' function is used to execute Python commands from MATLAB. To execute a Python script file, the 'pyrunfile' function is used. The filename of the code snippet should be passed as an argument to the 'pyrunfile' function. The following code illustrates the usage of the 'pyrunfile' function:

>>pyrunfile('webs_server.py')

Please refer the pyrunfile documentation for more information.

[Marcin Kowalski]

Thank you! I have no idea how I could missed this function.

Anyways, I made a step forward, but found another issue:

Python Error: ModuleNotFoundError: No module named 'websocket_server'

This is quite strange because the module is installed and added to the path. Is there any chance to see which modules/dependencies are visible for MATLAB?

[Bala Tripura Bodapati]

Hi Marcin,

It is my understanding that 'ModuleNotFoundError' error is encountered.In order to verify the libraries that are visible to MATLAB, ensure that the libraries are there in the Python sys.path :

py.sys.path

If not, you can install the libraries in the Python system path.

This issue can also be encounterd if more than 2 versions of Python are installed on your system.The right version can be configured using the following command:

pyenv('Version', 'C:\ProgramData\Anaconda3\python.exe')

Please refer below documentation for more information:

• Access Python modules from MATLAB
• Understanding Python and MATLAB import Commands