Python program run in MATLAB can't import pygame

Question

I'm trying to run a Python program, which uses the pygame modules, from MATLAB. I know I can use either

system('python program.py')

or just

! python program.py

However, I keep getting the error:

Traceback (most recent call last):
  File "program.py", line 1, in <module>
    import pygame
ImportError: No module named pygame

What is strange is that if I run the program from the command line, it works just fine. Does anyone know why if run from within MATLAB, Python can't find pygame?

Answer 1

The problem may be that MATLAB is not seeing your PYTHONPATH, which normally stores Python libraries and modules. For custom modules, PYTHONPATH should also include the path to your custom folders.

You can try setting the value of PYTHONPATH from within a MATLAB running session:

PATH_PYTHON = '<python_lib_folder>' 
setenv('PYTHONPATH', PATH_PYTHON); % set env path (PYTHONPATH) for this session
system('python program.py'); 

See also the possibly relevant SO answer here: How can I call a Qtproject from matlab?

Answer 2

As I haven't used matlab too often and don't have the program available now I cannot say for sure, but matlab may be creating a custom environment with custom paths (this happens a lot, so the user has a very consistent experience in their software). When matlab installs it may not export paths to its own modules to your default environment. So when calling for pygame.py outside of matlab, python cannot find pygame.py under its usual lookup paths.

Solutions could be:

• find the pygame.py, and map the path to it directly in your code, though this could cause you headaches later on during deployment

• Try just copying the pygame.py file to your working directory, could have dependences that need to addressed.

• Install pygame directly from its developer at http://www.pygame.org. Version differences could be a problem but pygame gets put under the usual lookup paths for python. (This would be my preferred solution personally.)

• Or just export the location of path to pygame in matlab's library to your default enivronment. This could be a problem during deployment too.