Python Functions, Modules, and Packages

Functions, Modules, and Packages

Modular code makes data pipelines reusable and testable.

Defining functions

def greet(name: str) -> str:
    """Return a friendly greeting."""
    return f"Hello, {name}!"

Importing standard modules

import math
from collections import Counter

print(math.sqrt(16))   # 4.0

Installing third‑party packages

pip install numpy pandas

Creating your own package

my_project/
│
├── my_package/
│   ├── __init__.py
│   └── utils.py
└── setup.py

utils.py could contain helper functions used across notebooks.