Importing Modules in Python

A module is a file containing Python definitions and code — typically .py files. Modules allow you to:

Organize your code Reuse code across projects Access Python’s built-in modules Use external libraries

To access a module, you use the import statement.

Syntax of Import

import module_name

Or:

import module_name as alias

Or:

from module_name import specific_function_or_class

Example 1: Importing a Built-in Module

import math
 
print("Square root of 16 is", math.sqrt(16))

Square root of 16 is 4.0

Explanation:

• math is a built-in module.
• After import, use module_name.function() to call functions.

Example 2: Using Alias with as

import math as m
 
print("Cosine of 0 is", m.cos(0))

Cosine of 0 is 1.0

Explanation:

• as keyword creates an alias to shorten long module names.

Example 3: Importing Specific Functions

from math import pow, sqrt
 
print("2 to the power 3 is", pow(2, 3))
print("Square root of 25 is", sqrt(25))

2 to the power 3 is 8.0
Square root of 25 is 5.0

Explanation:

• You can import only the needed functions from a module.
• No need to prefix with module name.

Example 4: Importing All Functions (Not Recommended)

from math import *
 
print(sin(0))
print(cos(0))

0.0
1.0

Explanation:

• from module import * imports everything.
• Risk: Can pollute namespace and cause name conflicts.

Example 5: Importing Custom Modules

You can create your own module — just a .py file — and import it.

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

Now import and use it:

import mymodule
 
print(mymodule.greet("Alice"))

Hello, Alice!

Explanation:

• Any .py file in the project folder can be imported.
• Helps to organize large programs into smaller files.

How Python Finds Modules

Python looks for modules in:

1. Current directory (your project)
2. PYTHONPATH (optional environment variable)
3. Standard library
4. Installed packages (site-packages)

To check module search paths:

import sys
print(sys.path)

Summary

• Use import to reuse code from other modules.
• You can import entire modules or specific functions.
• Organizing your project with modules makes code cleaner and easier to maintain.
• You can import both built-in modules and custom modules.

In the next section, we will explore the Python Standard Library — a powerful collection of modules included with Python.

If you’d like, I’ll proceed with the next section — Standard Library Overview — with the same style and level of detail. Just confirm! 🚀