Python Modules and Imports Explained Simply

Modules help organize code by splitting it into separate files. They make programs easier to manage and allow code reuse.

What is a module?

A module is a Python file (.py) containing functions, variables, or classes.

For example, create a file named math_utils.py:

def add(a, b):
    return a + b

def multiply(a, b):
    return a * b

pi = 3.14159

This file is now a module.

Importing modules

Use import to load a module.

import math_utils

result = math_utils.add(5, 3)
print(result)  # 8

print(math_utils.pi)  # 3.14159

Import specific items:

from math_utils import add, pi

print(add(10, 20))  # 30
print(pi)          # 3.14159

Import everything (not recommended for large modules):

from math_utils import *

print(multiply(4, 5))  # 20

Using built-in modules

Python has many built-in modules.

Random module:

import random

print(random.randint(1, 10))  # Random number between 1 and 10
print(random.choice(["apple", "banana", "cherry"]))  # Random item

Math module:

import math

print(math.sqrt(16))   # 4.0
print(math.pi)         # 3.141592653589793

Aliasing for shorter names

Give a module a shorter name with as:

import random as rnd

print(rnd.randint(1, 100))

Simple examples

Create a greeting module greet.py:

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

def goodbye(name):
    return f"Goodbye, {name}!"

Use it in main file:

from greet import hello, goodbye

print(hello("Alex"))
print(goodbye("Sam"))

Important notes

• The module file must be in the same folder or in Python's path.
• Use descriptive module names (lowercase, underscores).
• Avoid from module import * in larger programs (can cause name conflicts).
• Modules are loaded only once per program run.

Quick summary

• Modules are separate .py files with reusable code.
• Import with import module or from module import item.
• Use as for aliases.
• Built-in modules like random and math provide extra functionality.
• Organize code into modules for better structure.

Practice creating and importing small modules. They are essential for building larger Python programs.