Lesson 15: Modules and Packages

Modules and packages are essential concepts in Python that help organize and structure code into reusable and manageable components. A module is a single file containing Python definitions, functions, and classes. A package is a collection of modules organized in a directory hierarchy.

Let’s explore modules and packages in Python:

# Importing modules
import math

# Using functions from the math module
print("Square root of 16:", math.sqrt(16))
print("Value of pi:", math.pi)

# Importing specific functions from a module
from random import randint, choice

# Using functions from the random module
print("Random number between 1 and 10:", randint(1, 10))
print("Random choice from a list:", choice(["apple", "banana", "cherry"]))

# Importing an entire module with an alias
import datetime as dt

# Using the datetime module with the alias
current_date = dt.date.today()
print("Current date:", current_date)

# Importing a module from a package
from mypackage import mymodule

# Using a function from the imported module
mymodule.greet()

# Creating a package structure
# mypackage/
#     __init__.py
#     mymodule.py

# Contents of mymodule.py
# def greet():
#     print("Hello, from mymodule!")

# Contents of __init__.py (can be empty)

Explanation:

• We can import modules using the import keyword, followed by the module name.
• We can access the functions, classes, and variables from the imported module using dot notation (module_name.function() or module_name.variable).
• We can import specific functions from a module using the from keyword, followed by the module name and the specific function names separated by commas.
• We can assign an alias to a module using the as keyword, allowing us to use a shorter name to reference the module.
• We can import modules from packages by specifying the package name and the module name separated by dot notation.

Now it’s time for a practical task:

Task 15:

Create a package called shapes with two modules, rectangle and circle. In the rectangle module, define a function calculate_area() that calculates the area of a rectangle given its width and height. In the circle module, define a function calculate_area() that calculates the area of a circle given its radius. Import both modules and calculate the areas of a rectangle and a circle.

Once you’ve completed the task, you can proceed to the next lesson.