LESSON 8: MODULES

🔹 A module is any Python file (.py) that contains Python code: variables, functions, or classes. 

🔹 You can import and use this code in another file instead of writing it again.

Real-life analogy:

Think of a module as a power tool. Instead of building a new tool from scratch every time, you import the tool (module) and use it.

🔹 A built-in module is a standard Python file that contains predefined functions, classes, and variables.

🔹 This modules comes with Python itself. You don’t need to install anything extra to use it.

🔹 You must import the module using the import keyword before you can use its tools.

Python Syntax

import module_name

module_name.function_name(arguments)

Python Code

import math 

print("Square root of 49:", math.sqrt(49))   # Output: 7.0

print("Value of pi:", math.pi)               # Output: 3.14159...

import random

print(random.randint(1, 10))        # Random integer from 1 to 10

print(random.choice(['A', 'B', 'C']))  # Random choice from list

import datetime

now = datetime.datetime.now()

print("Current time:", now)

print("Today's date:", datetime.date.today())

✅ Try It:

Open Google Colab, create a new notebook, and run the examples above in new code cells.

WHY USE BUILD-IN MODULES❓ 

🔹 Save time: no need to write your own math or date functions

🔹 Improve readability: code is cleaner and easier to understand

🔹 Standardized: reduces bugs, since the module is well-tested

🔹 Foundation for libraries like pandas, NumPy, matplotlib, etc.

🔧 HANDS-ON TASK 1

Use the random module to create a function that simulates rolling a six-sided die:

Python Code

import random

def roll_die():

   return random.randint(1, 6)

print("You rolled a", roll_die())

✅ Try It:

Run the examples above in new code cells.

🔧 HANDS-ON TASK 2 (15 minutes) 

You are helping organize a virtual Lucky Draw Contest for a college event. Participants have registered online, and their names are stored in a list. Your task is to write a Python program that randomly selects winners using the random module.

You are given a list of participant names. Your program should:

1. Randomly select one grand prize winner

2. Randomly select three consolation prize winners (without repeating the grand prize winner)

3. Display the results neatly

Sample Data: 

participants = ["Afiq", "Zara", "Daniel", "Liyana", "Nina", "Ravi", "Sofia","Haris", "Esha", "Kavya", "Arjun", "Bella", "Nabil", "Farah"]

Step 1: Import random module

Step 2: Randomly select 1 grand price winner

Step 3: Select 3 unique consolation winners

Step 4: Final Output

🔹 Instead of importing an entire module, you can choose to import only the functions, classes, or constants you need. 

🔹 This is called a specific import.

🔹 It’s useful when:

🔸 You only need one or two tools from a large module

🔸 You want to write cleaner and shorter code

🔸 You want to avoid naming conflicts

Python Syntax

from module_name import function1, function2

Python Code

from math import sqrt, pi

print("Square root of 49 is", sqrt(49))  # 7.0

print("Value of pi is", pi)              # 3.1415...

# No need to write math.sqrt()

from random import randint, choice

print(randint(1, 100))        # Random number between 1 and 100

print(choice(['red', 'blue']))  # Randomly selects an item

from datetime import datetime, timedelta

now = datetime.now()

print("Now:", now)

future = now + timedelta(days=5)

print("Five days later:", future)

✅ Try It:

Run the examples above in new code cells.

WHY IMPORT SPECIFIC FUNCTIONS❓ 

🔹 Clean code: don’t need to prefix with the module name

🔹 Performance: slightly faster in large programs (since less is loaded)

🔹 Avoid conflicts: avoid name clashes with other modules

🔹 Focus: Keeps your imports limited to what’s actually used

🔧 HANDS-ON TASK 1

Try importing only specific functions from statistics:

Python Code

from statistics import mean, median

data = [12, 15, 18, 21, 24]

print("Mean:", mean(data))

print("Median:", median(data))

✅ Try It:

Run the examples above in new code cells.

🔧 HANDS-ON TASK 2 (15 minutes)

You are developing a simple fitness tracking program for beginners. One of the features is calculating the distance covered by a user while jogging or walking in a circular park.

The park has a circular track, and users record the number of laps and the radius of the track (in meters). Your program should calculate the total distance walked using the formula for the circumference of a circle:

Distance=2×π×radius×laps

To simplify and write clean code, you'll import only the pi function from Python’s built-in math module.

Create a Python program that:

1. Imports only the pi constant from the math module

2. Accepts the radius of the track and number of laps as user input

3. Calculates and displays the total distance walked in meters

4. Rounds the result to 2 decimal places

Step 1: Import only pi 

Step 2: Get user input (radius and lap)

Step 3: Calculate the distance

Step 4: Display Output 

🔹 An alias is an alternate name you give to a module or function when you import it. 

🔹 You use the as keyword to assign the alias. 

🔹 Best practices using alias:

1. Use common aliases (pd, np, plt) — they’re universally recognized.

2. Choose short, clear aliases if you’re making custom ones.

3. Don’t use confusing or unrelated aliases.

Python Syntax

import module_name as alias

Python Code

import math as m

print(m.sqrt(36))     # Output: 6.0

print(m.pi)           # Output: 3.1415...

import random as rnd

lucky_number = rnd.randint(1, 100)

print("Your lucky number is:", lucky_number)

import datetime as dt

current_time = dt.datetime.now()

print("Current time:", current_time)

✅ Try It:

Run the examples above in new code cells.

🔧 HANDS-ON TASK (15 minutes)

You are developing a simple program called "Daily Inspiration" that displays a random motivational quote along with the date and time it was shown. The program will be part of a digital dashboard for students and staff.

To keep the code clean and professional, you decide to:

1. Use the random module with the alias rnd

2. Use the datetime module with the alias dt

quotes = [

    "Believe you can and you're halfway there.",

    "Success is not final, failure is not fatal.",

    "Do one thing every day that scares you.",

    "Hard work beats talent when talent doesn't work hard.",

    "Stay hungry. Stay foolish."

]

Step 1: Import modules with aliases

Step 2: Create a list of motivational quotes

Step 3: Select a random quote and get the current time

Step 4: Display the quote with the timestamp

STYLE USAGE WHEN TO USE EXAMPLE

Full Module Import Access full module using prefix need many functions from a module import math

 math.sqrt(25)

Specific Import Access only selected functions need only 1–2 functions from math import sqrt 

/classes     sqrt(25)

Using Alias Shorten module name the module name is long import pandas as pd

   pd.DataFrame()

🔹 STEP 1: Create a Python File with Reusable Code

File name: my_math.ipynb

Python Code

def add(a, b):

   return a + b

def subtract(a, b):

   return a - b

🔹 STEP 2: Create Another Python File to Use the Module

File name: main.ipynb

Python Code

import my_math

print("Addition:", my_math.add(10, 5))

print("Subtraction:", my_math.subtract(10, 5))

NOTE: my_math.ipynb need to be in the same folder as main.ipynb

🔹 Alternative: Import Specific Functions

Python Code

from my_math import add

print(add(7, 3))  # Only importing and using `add`

✅ Try It:

Run the examples above in new code cells.

🔧 HANDS-ON TASK 1

You are asked to build a simple greeting system using two separate Python files:

Part 1: Create a Module (greeting.ipynb)

File name: greeting.py

Python Code

def say_hello(name):

   return f"Hello, {name}!"

def say_goodbye(name):

   return f"Goodbye, {name}!"

Part 2: Create a Main Program (app.ipynb)

File name: app.py

Python Code

import greeting

print(greeting.say_hello("Afiq"))

print(greeting.say_goodbye("Afiq"))

NOTE: greeting.ipynb need to be in the same folder as app.ipynb

✅ Try It:

Run the examples above in new code cells.

🔧 HANDS-ON TASK 2 (15 minutes)

You’ll write a module called text_utils.py with functions like:

• Counting the number of words in a string

• Reversing a sentence

• Making all text uppercase

Then, you'll use those functions in another script.

Step 1: Create a new file named text_utils.py

Step 2: Create another file called main.py

Sample Output:

Original: Python makes coding fun and powerful

Word count: 6

Reversed: lufrewop dna nuf gnidoc sekam nohtyP

Uppercase: PYTHON MAKES CODING FUN AND POWERFUL

🧠 Answer these to test your understanding.

1. What is a Python module?

a) A block of repeated code

b) A built-in function

c) A Python file containing reusable code

d) A folder of images

2. Which of the following correctly imports an entire module?

a) from math import sqrt

b) import sqrt from math

c) import math

d) math import

3. Which statement imports only the pi constant from the math module?

a) import math.pi

b) from math import pi

c) math from import pi

d) include math.pi

4. What is an alias in Python imports used for?

a) Hiding a module

b) Creating a backup

c) Shortening the module name

d) Encrypting data

5. You can only import built-in Python modules, not your own (T/F).

6. The same function name can be used in different modules (T/F).

7. import my_module will work only if my_module.py is in the same directory or Python path (T/F).

8. You must always use as when importing a module (T/F).

🔧 Instructions:

Task Title: Student Helper Module: Your Academic Assistant

By completing this task, you will:

• Understand how to write and save your own Python module

• Practice writing simple functions inside a separate .py file

• Import your custom module into another Python script

• Use imported functions to perform tasks and display output

You are building a student helper system that helps calculate average marks and determine grades. Your solution should be organized using two separate Python files:

PART A: A module file that contains the logic

PART B: A main program that uses (imports) the module

Part A: Create Your Module File

1. Open your Google Colabs

2. Create a new notebook and save it as: student_helper.py

3. Inside student_helper.py, write and save the following functions: calculate_average and get_grade.

  Part B: Create Your Main Program

1. In the same folder, create another new file and save it as: main.py

2. In main.py, do the following:

• Import your module using: import student_helper

• Ask the user to enter three subject marks using input()

• Call the calculate_average() function from the module

• Call the get_grade() function using the average value

• Display the average (2 decimal places) and the grade

✅ Hint: You will need to convert the user input to numbers using float().

🔹 A module is any .py file that can be imported.

🔹 You can reuse code by importing it from other modules.

🔹 Built-in modules like math and random offer ready-made tools.

🔹 You can import the whole module, specific items, or use aliases.

🔹 Organizing code into modules makes your projects scalable and maintainable.