Python Modules

A Module in python is a file containing definitions and statements. A module can define functions, classes and variables. Modules help organize code into separate files so that programs become easier to maintain and reuse. Instead of writing everything in one place, related functionality can be grouped into its own module and imported whenever needed.

Create a Python Module

To create a Python module, write the desired code and save that in a file with .py extension. Let's understand it better with an example:

Example: Let's create a calc.py in which we define two functions, one add and another subtract.

# calc.py def add(x, y): return (x+y) def subtract(x, y): return (x-y) 

This is all that is required to create a module.

Import module

Modules can be used in another Python file using the import statement. When Python sees an import, it loads the module if it exists in the interpreter’s search path.

Syntax:

import module

Example: Now, we are importing the calc that we created earlier to perform add operation.

import calc print(calc.add(10, 2)) 

Output

12

Explanation: import calc loads the module and calc.add() accesses a function through dot notation.

Types of Import Statements

1. Import From Module: This allows importing specific functions, classes, or variables rather than the whole module.

from math import sqrt, factorial print(sqrt(16)) print(factorial(6)) 

4.0 720 

Explanation: Only sqrt and factorial are brought into the local namespace, so the prefix math. is not required.

2. Import All Names: * imports everything from a module into the current namespace.

from math import * print(sqrt(16)) print(factorial(6)) 

4.0 720 

Explanation: Every public name of math becomes directly accessible. (Not recommended in large projects due to namespace conflicts.)

3. Import With Alias: You can shorten a module’s name using as.

import math as m print(m.pi) 

3.141592653589793 

Explanation: math is accessed through the shorter alias m.

Types of Modules in Python

Python provides several kinds of modules. Each type plays a different role in application development.

1. Built-in Modules: These come bundled with Python and require no installation - e.g., math, random, os.

import random print(random.randint(1, 5)) 

4 

Explanation: random.randint() returns a random number within the given range.

2. User-Defined Modules: These are modules you create yourself, such as calc.py.

import calc print(calc.sub(20, 5)) 

Output

15

Explanation: The module is created manually and then imported into another script.

3. External (Third-Party) Modules: These modules are installed using pip - e.g., NumPy, Pandas, Requests.

import requests r = requests.get("https://example.com") print(r.status_code) 

Output

200

Explanation: requests is installed separately (pip install requests) and provides HTTP utilities.

4. Package Modules: A package is a directory containing multiple modules, usually with an __init__.py file.

Example Directory

mypkg/
__init__.py
calc.py
utils.py

Using a module from a package

from mypkg import utils print(utils.some_func()) 

calls a function named some_func(), the output will be whatever that function returns.

If utils.py contains something like:

def some_func(): return "Hello" 

Output

Hello

Locating a Module

Python searches for modules in a predefined list of directories known as the module search path. You can view this list using sys.path.

import sys for p in sys.path: print(p) 

/home/guest/sandbox /usr/local/lib/python313.zip /usr/local/lib/python3.13 /usr/local/lib/python3.13/lib-dynload /usr/local/lib/python3.13/site-packages 

Explanation: Python checks each path in order until it finds the module you’re trying to import.

Also Read:

• Basics Of Python Modules
• How to Install a Python Module?
• 10 Interesting modules in Python to play with