A module in Python is a file that contains Python code, typically including functions, classes, and variables. Modules help organize and reuse code efficiently.
1. What is a Python Module?
A module is simply a .py file containing reusable code. Python provides built-in modules, and you can also create custom modules.
Example of a Simple Module:
Create a file mymodule.py with the following code:
def greet(name):
return f"Hello, {name}!"
Now, import and use it in another Python file:
import mymodule
print(mymodule.greet("Alice")) # Output: Hello, Alice!
2. Importing Modules
Python provides multiple ways to import modules:
import module_name– Imports the whole module.from module_name import function_name– Imports specific functions or variables.import module_name as alias– Imports with an alias.from module_name import *– Imports everything (not recommended).
Example:
import math
print(math.sqrt(16)) # Output: 4.0
from math import pi
print(pi) # Output: 3.141592653589793
import math as m
print(m.factorial(5)) # Output: 120
3. Built-in Python Modules
Python has many built-in modules, such as:
- math – Mathematical functions
- random – Generating random numbers
- datetime – Handling dates and times
- os – Interacting with the operating system
- sys – System-specific parameters and functions
Example of Using random Module:
import random
print(random.randint(1, 10)) # Generate a random number between 1 and 10
4. Creating and Using Custom Modules
You can create your own module by saving Python functions in a .py file and importing them.
Example:
Create calculator.py with:
def add(a, b):
return a + b
Now, use it in another file:
import calculator
print(calculator.add(5, 3)) # Output: 8
5. The __name__ Variable in Modules
When a Python script runs, the __name__ variable determines if the script is being run directly or imported.
Example:
if __name__ == "__main__":
print("This script is run directly!")
else:
print("This script is imported as a module.")
6. The dir() Function
The dir() function lists all attributes and methods of a module.
Example:
import math
print(dir(math))
7. Installing External Modules using pip
Python allows installing third-party modules using pip, the package manager.
Example:
pip install requests
Now, use the installed module:
import requests
response = requests.get("https://www.example.com")
print(response.status_code)
8. Summary
✅ Modules help organize and reuse Python code efficiently.
✅ Built-in modules like math, random, and os simplify complex tasks.
✅ Custom modules allow the creation of reusable functions.
✅ The __name__ variable differentiates between script execution and module import.
✅ External modules can be installed via pip.
