September 11, 2024

Python Tutorials

Python Modules

In Python, a module is a file containing Python definitions, functions, and statements. Modules allow you to logically organize your Python code, making it reusable and easier to manage. A module can define functions, classes, and variables, and it can also include runnable code.

1. Importing Modules

You can import a module using the import statement. Once a module is imported, you can use its functions and variables.

import math
result = math.sqrt(16)
print(result)

2. Importing Specific Functions or Variables

You can import specific functions or variables from a module using the from ... import statement.

from math import pi, sqrt
print(pi)        
print(sqrt(16))

3. Renaming a Module

You can rename a module while importing it using the as keyword.

import math as m
print(m.sqrt(16))

4. Creating Your Own Module

You can create your own module by saving Python code in a file with a .py extension. The filename becomes the module name.

# mymodule.py
def greet(name):
    return f"Hello, {name}!"

# In another Python file or interpreter
import mymodule
print(mymodule.greet("Alice"))

5. Built-in Python Modules

Python comes with a standard library of built-in modules that provide many useful functions and classes.

  • math: Provides mathematical functions.
  • os: Provides a way of using operating system-dependent functionality.
  • sys: Provides access to some variables used or maintained by the Python interpreter.
  • datetime: Supplies classes for manipulating dates and times.
  • random: Implements pseudo-random number generators for various distributions.
import datetime
current_time = datetime.datetime.now()
print(current_time)

6. Exploring Module Contents

You can use the dir() function to list all the functions, classes, and variables in a module.

import math
print(dir(math))

7. The __name__ Variable

Every Python module has a special attribute called __name__. When a module is run as the main program, the __name__ variable is set to "__main__". If the module is being imported into another module, __name__ is set to the module’s name.

# mymodule.py
if __name__ == "__main__":
    print("This is the main program.")
else:
    print("This module has been imported.")

8. Installing External Modules

You can install external Python modules using pip, the Python package manager.

pip install requests
import requests
response = requests.get('https://api.github.com')
print(response.status_code)

9. Python Package

A package is a collection of Python modules organized in directories. Each package in Python is a directory that must contain a special file called __init__.py. This file can be empty but indicates that the directory is a package.

# Directory structure
my_package/
    __init__.py
    module1.py
    module2.py

# Importing a module from a package
from my_package import module1

10. Commonly Used Python Modules

  • os: Provides a way of using operating system-dependent functionality like reading or writing to the file system.
  • sys: Provides access to some variables used or maintained by the Python interpreter.
  • re: Provides regular expression matching operations.
  • json: Provides functions for working with JSON data.
  • datetime: Provides classes for manipulating dates and times.
  • subprocess: Allows you to spawn new processes, connect to their input/output/error pipes, and obtain their return codes.
  • random: Implements pseudo-random number generators for various distributions.

Modules are a crucial part of Python programming, enabling code reusability, organization, and modular design. By dividing your code into modules, you can make your programs more manageable and maintainable.

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