How to Call a Python Script from MATLAB

Integrating Python scripts with MATLAB can significantly enhance your workflow, especially when leveraging Python's extensive libraries for data analysis, machine learning, or automation. This guide will walk you through the most efficient ways to call a Python script from MATLAB using the py module, which is the most popular and widely used method.

Prerequisites

Before proceeding, ensure you have the following:

MATLAB installed (version R2014b or later, as Python integration was introduced then).
Python installed (MATLAB supports Python 2.7, 3.6, or later).
MATLAB configured to use your Python interpreter. You can check this by running:

pyversion

If MATLAB doesn’t detect Python, set the path manually:

pyversion('/path/to/python/executable')

Method 1: Using the `py` Module

The simplest way to call Python from MATLAB is by using the built-in py module. This allows you to directly access Python functions, modules, and scripts.

Step 1: Write a Python Script

Create a simple Python script, e.g., hello.py, with a function:

def greet(name):
    return f"Hello, {name}!"

Step 2: Call the Python Function from MATLAB

In MATLAB, use the py module to import and call the function:

% Add the Python script's directory to the path
if count(py.sys.path, '') == 0
    insert(py.sys.path, int32(0), '';
end

% Call the Python function
result = py.hello.greet('MATLAB');
disp(result);

This will output: Hello, MATLAB!

Method 2: Running a Python Script as a Command

If you need to execute an entire Python script (not just a function), use MATLAB's system command:

% Run the Python script
[status, result] = system('python hello.py');
disp(result);

This method is useful for standalone scripts that don’t require returning data to MATLAB.

Method 3: Using MATLAB’s `pyrunfile` (R2019b+)

For newer MATLAB versions, pyrunfile allows running a Python script and capturing variables:

% Execute script and fetch variables
pyrunfile("hello.py");
greeting = pyrun("greet('MATLAB')", "greeting");
disp(greeting);

Tips for Smooth Integration

Data Type Conversion: MATLAB and Python handle data types differently. Use py.list, py.dict, or numpy arrays for seamless conversion.
Error Handling: Wrap Python calls in try-catch blocks to manage exceptions.
Performance: For heavy computations, avoid frequent calls between MATLAB and Python. Instead, batch process data.

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