🔒 Encapsulation in Python — Keeping Your Data Safe!

 Have you ever saved a secret in your diary with a lock? Or kept your chocolate hidden in a secret drawer? 🍫

That’s Encapsulation in real life!

In Python, Encapsulation is a way to hide or protect data so only certain parts of your code can use or change it. It helps kyour programs safe and organized — just like putting your stuff in a locker with a key!

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🧠 What is Encapsulation?

Encapsulation means bundling data and the methods that work on that data into one unit — a class.

But more importantly:

• It hides private data

• It only allows controlled access

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📦 Real-life Analogy

Think of a mobile phone:

• You can use it (call, play games)

• But you can’t open it and change the battery or circuit

That’s encapsulation — some parts are visible, and some are hidden to protect the system!

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🐍 Let’s Learn with Python!

🎒 Class with Protected Data

class Student:
    def __init__(self, name, marks):
        self.name = name
        self.__marks = marks  # __ makes it private

    def show_info(self):
        print(f"Name: {self.name}, Marks: {self.__marks}")

    def update_marks(self, new_marks):
        if new_marks >= 0:
            self.__marks = new_marks
        else:
            print("Marks can't be negative!")

📚 Try it Out:

s1 = Student("Aryan", 85)
s1.show_info()
s1.update_marks(90)
s1.show_info()

# Let's try to change marks directly
s1.__marks = 30
s1.show_info()  # Still shows 90!

💬 Output:

Name: Aryan, Marks: 85
Name: Aryan, Marks: 90
Name: Aryan, Marks: 90

Why didn't s1.__marks = 30 work?

Because __marks is private — only accessible inside the class!

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🕵️‍♂️ Accessing Private Data (Not Recommended)

You can access private data using a special trick, but it’s not safe and not advised:

print(s1._Student__marks)

This works, but we should avoid it. Instead, use getter/setter methods like update_marks().

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✅ Why Use Encapsulation?

Advantage	What it Means
🎯 Controlled Access	Only allow safe changes to data
🔒 Data Protection	Hide sensitive data from outside access
📦 Clean Organization	Keep code tidy and manageable
🚫 Prevent Misuse	Stop users from breaking your class logic

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🎮 Challenge for You!

Create a class BankAccount with:

• Private balance

• Method to show balance

• Method to deposit and withdraw money

• Prevent withdrawal if not enough money

Can you do it? Try it in your Python editor!

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🧠 In Short

• Encapsulation = Wrapping data and methods into a class

• Use __variable to make it private

• Control access with functions inside the class

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📘 Exercise 

1. Private Attribute Creation

Create a BankAccount class with:

• A private attribute __balance

• A method deposit(amount) to increase balance

• A method get_balance() to return the balance
  Task: Create an object, deposit ₹1000, and print the balance.

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2. Name Mangling Access

Using the BankAccount class from Q1, try accessing the __balance attribute directly from outside the class using name mangling.
Task: Demonstrate how to read and modify it without using getter/setter.

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3. Private Method

Create a Car class with:

• A private method __engine_start() that prints "Engine started"

• A public method start() that calls the private method
  Task: Create an object and start the car.

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4. Getter & Setter Methods

Create a Student class with a private attribute __marks.

• Write getter and setter methods for marks.

• The setter should validate that marks are between 0 and 100, otherwise reject.
  Task: Test with valid and invalid marks.

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5. Property Decorator

Rewrite Q4 using @property and @marks.setter instead of getter/setter methods.
Task: Show that student.marks = 85 works directly.

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6. Encapsulation for Read-Only Attribute

Create a Book class with:

• A private attribute __isbn

• A read-only property isbn
  Task: Try changing ISBN from outside and show it fails.

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7. Encapsulation in Inheritance

Create a Person class with a private attribute __age.
Create a Teacher class that inherits from Person.
Task: Show that Teacher objects cannot access __age directly.

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8. Encapsulation with Method Overriding

Create a Device class with:

• A private attribute __status

• A public method turn_on() that sets status to "ON"

• A public method turn_off() that sets status to "OFF"
  Create a subclass SmartDevice that overrides turn_on() to print "Smart device starting..." before turning on.
  Task: Demonstrate usage.

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9. Encapsulation with List of Objects

Create a Library class with:

• A private list __books

• Methods add_book(title) and get_books()
  Task: Add books and print them without directly accessing __books.

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10. Secure Attribute Access

Create a User class with:

• Private attribute __password

• Method set_password(pwd) that stores password only if it meets certain criteria (min 8 chars, contains number & letter)

• Method check_password(pwd) to verify if entered password matches stored one
  Task: Test with valid and invalid passwords.

🧠 Polymorphism in Python — One Name, Many Forms!

 Have you ever seen your teacher write with a pen, then with a marker, and then type on a keyboard?

All three are different, but the action is the same: writing ✍️

This is exactly what Polymorphism means in Python — one function or method can work in many different ways depending on the object!

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🎭 What is Polymorphism?

Polymorphism is a fancy word that comes from Greek:

• "Poly" means many

• "Morph" means forms

So Polymorphism = many forms 🌀

In Python, polymorphism allows us to:

• Use the same function name for different objects

• Write less code and do more work

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🧒 Real-Life Example: Animals Making Sounds

Let’s say we have different animals, and they all make sounds — but each makes a different sound.

class Dog:
    def speak(self):
        print("Woof! 🐶")

class Cat:
    def speak(self):
        print("Meow! 🐱")

class Cow:
    def speak(self):
        print("Moo! 🐮")

Now let’s call their speak() method:

animals = [Dog(), Cat(), Cow()]

for animal in animals:
    animal.speak()

💬 Output:

Woof! 🐶
Meow! 🐱
Moo! 🐮

🎉 Even though the method name is the same (speak()), each animal does something different. That’s Polymorphism in action!

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🔁 Polymorphism with Functions

You can also write a function that works with many object types:

def animal_sound(animal):
    animal.speak()

d = Dog()
c = Cat()

animal_sound(d)
animal_sound(c)

✅ The same function behaves differently depending on what you pass into it!

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🎮 Mini Challenge Time!

Create two classes:

• Car → method move() → prints "Driving on the road 🚗"

• Boat → method move() → prints "Sailing on water 🚤"

Then write a loop to call move() for both.

Can you do it? Try it out!

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🧠 Why Polymorphism is Cool:

Benefit	What it Means
✅ Less Repetition	No need to write same function again
🔁 Reusability	Use same function for different objects
📦 Clean Code	Easier to read and manage your program

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🔮 Summary

Term	What It Means
Polymorphism	One name, many behaviors
Method	A function inside a class
Class	A blueprint to create objects

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🧠 Real-World Examples

• print() works for text, numbers, and even lists!

print("Hello")
print(123)
print([1, 2, 3])

That’s built-in polymorphism in Python!

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🚀 Coming Next

• ✨ Encapsulation — hide your data like a secret vault

• 🧬 Inheritance — share features between parent and child classes

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🎁 Bonus: Try This!

class Shape:
    def area(self):
        print("I don't know the shape!")

class Square(Shape):
    def area(self):
        print("Area = side × side")

class Circle(Shape):
    def area(self):
        print("Area = π × r × r")

shapes = [Square(), Circle()]
for shape in shapes:
    shape.area()

🧬 Inheritance in Python – Coding Like a Family!

 Have you ever looked at your family and thought — “I have my mom’s smile” or “my dad’s sense of humor”? That’s inheritance in real life!

Guess what? In Python programming, classes can inherit features from other classes — just like kids inherit features from parents.

Let’s explore this magical concept called Inheritance in a super simple way! 🪄

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👪 What is Inheritance?

In Python, Inheritance means that one class (child) can use the properties and methods of another class (parent).

📦 Why is this useful?

• Reuse code without writing everything again

• Keep your programs clean and organized

• Add extra features only where needed

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🧒 Real-Life Example: Parent and Child

Let’s say we have a parent class called Person, and a child class called Student.

# Parent Class
class Person:
    def __init__(self, name):
        self.name = name

    def say_hello(self):
        print(f"Hello, I’m {self.name}!")

# Child Class
class Student(Person):
    def study(self):
        print(f"{self.name} is studying 📚.")

👶 Let's create a student!

s1 = Student("Anjali")
s1.say_hello()   # Inherited from Person
s1.study()       # From Student class

💬 Output:

Hello, I’m Anjali!
Anjali is studying 📚.

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🧠 How It Works

• Student inherits from Person

• Student gets access to say_hello() without writing it again

• We can add new features to Student like study()

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🚗 Another Example: Vehicle → Car

class Vehicle:
    def __init__(self, brand):
        self.brand = brand

    def move(self):
        print(f"{self.brand} is moving!")

class Car(Vehicle):
    def honk(self):
        print(f"{self.brand} says beep beep! 🚗")

my_car = Car("Tata")
my_car.move()
my_car.honk()

💬 Output:

Tata is moving!
Tata says beep beep! 🚗

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🔁 What if We Want to Change Inherited Behavior?

We can override the parent’s method in the child class:

class Dog:
    def speak(self):
        print("Woof! 🐶")

class Puppy(Dog):
    def speak(self):
        print("Yip yip! 🐕‍🦺")  # Overriding the method

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🎮 Quick Coding Challenge:

Can you create these classes?

1. Animal → has method breathe()

2. Fish (inherits from Animal) → has method swim()

Try writing the code and show it to your teacher or friends!

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✨ Summary

Term	Meaning
Class	A blueprint for objects
Inheritance	One class gets features from another
Parent	The base class
Child	The class that inherits

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🔮 Coming Up Next

• 🧬 Multiple Inheritance (inheriting from more than one class)

• 🔒 Encapsulation (protecting your data)

• 🧠 Polymorphism (same name, different actions)

🐍 Object-Oriented Programming in Python — A Fun Guide for Students!

 Have you ever played a video game where you control a character like Mario, Sonic, or Pikachu? What if I told you that you can create your own characters and control them using Python?

Welcome to the world of Object-Oriented Programming — or OOP for short!

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🎓 What is Object-Oriented Programming?

Object-Oriented Programming is a way to organize your code by bundling data and actions together. In OOP, we think of everything as objects, just like real life!

Let’s break it down:

• Class = Blueprint (like the recipe for a cake 🍰)

• Object = Real thing made from that blueprint (like the actual cake you eat!)

• Attributes = Data about the object (e.g., color, speed)

• Methods = Actions the object can do (e.g., jump, run, speak)

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🧒 Example: Let’s Make a Student!

class Student:
    def __init__(self, name, grade):
        self.name = name
        self.grade = grade

    def introduce(self):
        print(f"Hi, I'm {self.name} and I'm in grade {self.grade}.")

🔍 Here:

• Student is the class (blueprint)

• name and grade are attributes

• introduce() is a method

🎉 Let's create a student!

s1 = Student("Riya", 8)
s1.introduce()

💬 Output:

Hi, I'm Riya and I'm in grade 8.

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🏃 Add More Actions!

class Student:
    def __init__(self, name, grade):
        self.name = name
        self.grade = grade
        self.energy = 100

    def study(self):
        print(f"{self.name} is studying hard 📚!")
        self.energy -= 10

    def play(self):
        print(f"{self.name} is playing football ⚽!")
        self.energy -= 15

    def rest(self):
        print(f"{self.name} is taking a nap 😴.")
        self.energy += 20

    def show_energy(self):
        print(f"{self.name}'s energy is {self.energy}")

Now test it out:

s1 = Student("Riya", 8)
s1.study()
s1.play()
s1.rest()
s1.show_energy()

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🧠 Why Use OOP?

✅ Code becomes easier to organize
✅ Reuse the same structure for many objects
✅ Add more features without changing the whole program

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🧪 Mini Challenge for You

Can you create a class called Dog with:

• Attributes: name, breed

• Methods: bark(), sleep(), eat()

Try it in your notebook or Python editor and test it!

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✨ Wrap-Up

Object-Oriented Programming in Python helps you create cool, real-world models using code. Whether it’s a student, a car, a robot, or a dog — you can bring them to life with classes and objects.

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🚀 Coming Next:

• Inheritance: Like kids getting traits from parents

• Polymorphism: Same action, different results

• Encapsulation: Protecting your code's secrets

🐼 Let's Explore Pandas in Python – A Fun Guide for School Students!

 

👋 Introduction

Have you ever used Excel to create tables and analyze data? What if we told you Python can do all of that — and more — using a library called Pandas? 📊🐼

Pandas is like a super-smart assistant that helps Python handle data easily. It's perfect for students who want to play with numbers, lists, tables, and real-world data like marksheets, cricket scores, or class attendance.

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🧠 What is Pandas?

Pandas is a Python library that helps you store, analyze, and manipulate data just like Excel but with code!

🧪 Fun Fact:

The name Pandas comes from "Panel Data," a term used in statistics.

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✅ Why Should School Students Learn Pandas?

• Helps you work with tables of data easily

• Perfect for Science projects, maths stats, or IT assignments

• Gives you a real-world skill used in data science and AI!

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🛠️ How to Install Pandas?

Before using Pandas, install it by running:

pip install pandas

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📦 Importing Pandas in Your Code

python
import pandas as pd

Here, pd is just a nickname we use for Pandas to make writing code faster.

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📋 Pandas Data Structures

Pandas has two main data structures:

1. Series – Like a single column (like a list with labels)

2. DataFrame – Like an Excel sheet (table with rows and columns)

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🔢 1. Pandas Series

A Series is like a list, but each item has a label (called an index).

✨ Example:

python

import pandas as pd

marks = pd.Series([85, 90, 78, 92], index=["Math", "Science", "English", "History"])
print(marks)

🖨️ Output:

Math       85
Science    90
English    78
History    92
dtype: int64

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📊 2. Pandas DataFrame

A DataFrame is like a table. It's the most used tool in Pandas.

✨ Example:

python

import pandas as pd

data = {
    "Name": ["Aarav", "Diya", "Kabir"],
    "Math": [89, 76, 93],
    "Science": [90, 85, 88]
}

df = pd.DataFrame(data)
print(df)

🖨️ Output:

    Name  Math  Science
0  Aarav    89       90
1   Diya    76       85
2  Kabir    93       88

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🔍 Exploring the DataFrame

✅ View first few rows:

python

print(df.head())  # Shows top 5 rows

✅ Get column names:

python

print(df.columns)

✅ Get statistics:

python

print(df.describe())

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🎯 Real-Life Example – Class Marks

Let’s create a student marksheet!

python

import pandas as pd

marksheet = {
    "Student": ["Anaya", "Rohan", "Priya", "Arjun"],
    "English": [88, 76, 90, 85],
    "Math": [92, 81, 95, 87],
    "Science": [89, 78, 88, 91]
}

df = pd.DataFrame(marksheet)

print("🏫 Class Marksheet:")
print(df)

# Calculate Average Marks
df["Average"] = (df["English"] + df["Math"] + df["Science"]) / 3
print("\n📊 With Average Marks:")
print(df)

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✏️ Editing the Data

➕ Add a new column:

python

df["Grade"] = ["A", "B", "A+", "A"]

➖ Remove a column:

python

df.drop("Grade", axis=1, inplace=True)

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📁 Reading from a CSV File

If your data is stored in a file like students.csv, you can read it like this:

python

df = pd.read_csv("students.csv")
print(df)

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💾 Writing Data to a File

You can also save your data to a file:

python

df.to_csv("output.csv", index=False)

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🧪 Try it Yourself – Challenge Time! 🎯

1. Create a DataFrame for your daily study schedule (Subjects, Time in minutes)

2. Calculate the total study time in a day

3. Save it in a CSV file

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📊 Let's Make Graphs with Pandas!

Do you enjoy pictures more than numbers? Pandas lets you create beautiful charts and graphs to see patterns in your data clearly!

To create charts, we’ll use another Python library called matplotlib.

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🛠️ Install Matplotlib

Before using it, install the library:

pip install matplotlib

Then import it in your Python code:

python

import matplotlib.pyplot as plt

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📘 Example 1: Line Graph – Student Marks Over Subjects

python

import pandas as pd
import matplotlib.pyplot as plt

data = {
    "Subjects": ["Math", "Science", "English", "History"],
    "Anaya": [92, 89, 88, 85],
    "Rohan": [81, 78, 76, 80]
}

df = pd.DataFrame(data)

# Plotting Line Graph
plt.plot(df["Subjects"], df["Anaya"], label="Anaya", marker='o')
plt.plot(df["Subjects"], df["Rohan"], label="Rohan", marker='s')

plt.title("📈 Marks Comparison")
plt.xlabel("Subjects")
plt.ylabel("Marks")
plt.legend()
plt.grid(True)
plt.show()

🎨 This shows how marks change across subjects for each student.

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📘 Example 2: Bar Graph – Student Average Marks

python

import pandas as pd
import matplotlib.pyplot as plt

data = {
    "Student": ["Anaya", "Rohan", "Priya", "Arjun"],
    "Average Marks": [89.6, 78.3, 91.0, 87.6]
}

df = pd.DataFrame(data)

# Bar Chart
plt.bar(df["Student"], df["Average Marks"], color='skyblue')
plt.title("📊 Average Marks of Students")
plt.xlabel("Student")
plt.ylabel("Average Marks")
plt.ylim(0, 100)
plt.show()

🎨 This bar chart gives a quick view of how each student performed overall.

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📘 Example 3: Pie Chart – Time Spent on Subjects

python

import pandas as pd
import matplotlib.pyplot as plt

data = {
    "Subject": ["Math", "Science", "English", "History"],
    "Time Spent (mins)": [60, 45, 30, 15]
}

df = pd.DataFrame(data)

# Pie Chart
plt.pie(df["Time Spent (mins)"], labels=df["Subject"], autopct='%1.1f%%', startangle=140)
plt.title("🕒 Study Time Distribution")
plt.show()

🎨 Great for understanding how you divide time between subjects.

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💡 Tips for Better Charts

• Always label axes!

• Add a title so people know what it shows.

• Use different colors for better clarity.

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🧪 Try it Yourself – Challenge Time! 🎯

Make a graph showing your weekly screen time for activities like:

• YouTube

• Games

• Study

• Social Media

Use a bar or pie chart to show where your time goes!

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🎓 Final Thoughts

Pandas is an amazing tool to help you become a data expert while still in school! Whether it's your marks, hobbies, sports scores, or class surveys — Pandas makes everything easier to analyze and visualize.

Learning Pandas and visualizing data using graphs and charts makes you think like a data scientist — solving real-world problems with numbers and pictures.

Whether it's school marks, study hours, or cricket scores — you can turn boring tables into colorful charts in seconds!