Modules and Packages

As programs grow, putting all code in a single file becomes unwieldy. Python uses modules and packages to organize code.

What is a Module?

A module is simply a Python file (.py) containing code (functions, variables, classes). The file name is the module name.

Importing Modules

The import statement brings the contents of another module into the current file.

1. Simple Import

python

Assumes a file named 'math_helpers.py' exists

import math_helpers

Access functions using the module name prefix

result = math_helpers.calculate_something()

2. Import with Alias (as)

Used to shorten long module names.

python import pandas as pd

df = pd.DataFrame(...)

3. Importing Specific Items (from...import)

Imports only specified functions, classes, or variables, allowing them to be used without the module prefix.

python from math import sqrt, pi

print(sqrt(9)) # Use sqrt directly print(pi) # Use pi directly

4. Import Everything (from...import *)

Imports all public names. Generally discouraged as it can lead to name collisions and confusion about where functions originate.