Learn Python

This is Scrimba's official Python course featuring their unique interactive scrim format. It offers 58 interactive video lessons where you can pause the screencast and edit the instructor's code directly in your browser with no local setup required. Its great for hands-on learners who want to code actively during the lesson rather than passively watching. No prerequisites are required.

📚 58 interactive lessons covering Python fundamentals: variables, data types, strings, lists, dictionaries, loops, functions, and file handling—all with built-in coding challenges

⏰ Duration: 5.6 hours

🏃‍♂️ Self Paced with immediate start

🏆 Certificate: Free completion certificate included

Created by 👨‍🏫: Olof Paulson & Scrimba Team

🔗 Course Link


#Python #InteractiveLearning #FreeCertificate

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🐍Python Lists (Data Structures) 📦

🔹 1. What is a List?

A list is a sequence of values (items). They are ordered, changeable (mutable), and allow duplicate members. Defined by square brackets [].

Example:

my_list = ["apple", 3.14, True, 100]
print(my_list)

Output: ['apple', 3.14, True, 100]

🔹 2. Accessing List Items

Items are accessed by their index, which starts at 0 for the first item.

Example:

fruits = ["apple", "banana", "cherry"]
print(fruits[0]) # First item
print(fruits[2]) # Third item
print(fruits[-1]) # Last item

Output:
apple
cherry
cherry

🔹 3. Modifying List Items

You can change an item by referring to its index.

Example:

colors = ["red", "green", "blue"]
colors[1] = "yellow" # Change 'green' to 'yellow'
print(colors)

Output: ['red', 'yellow', 'blue']

🔹 4. Adding Items to a List

• .append(): Adds an item to the end of the list.
• .insert(index, item): Adds an item at a specific index.

Example:

names = ["Alice", "Bob"]
names.append("Charlie") # Add to end
names.insert(0, "David") # Add at the beginning
print(names)

Output: ['David', 'Alice', 'Bob', 'Charlie']

🔹 5. Removing Items from a List

• .remove(item): Removes the first occurrence of a specified item.
• .pop(index): Removes (and returns) the item at a specified index (or the last item if no index is given).
• del list[index]: Deletes the item at a specific index.

Example:

numbers = [10, 20, 30, 20, 40]
numbers.remove(20) # Removes first '20'
del numbers[0]     # Removes '10'
print(numbers)

Output: [30, 20, 40]

🎯 Today's Goal(What you should do)

✔️ Understand what lists are and how to create them
✔️ Access items using indexing
✔️ Modify, add, and remove items from lists

🐍 Python For Loops (Iteration) 🔄

For loops are used to iterate over a sequence (like a list, tuple, string, or range) or other iterable objects. They let you execute a block of code repeatedly for each item.

👉 They are essential for automating tasks and processing collections of data efficiently.

🔹 1. What is a For Loop?

A for loop executes a set of statements, once for each item in a collection.

Example:

for character in "Python":
    print(character)

Output:
P
y
t
h
o
n

🔹 2. Looping Through a List

This is one of the most common uses: going through each item in a list.

Syntax:

for item in list_name:
    # code to execute for each item

Example:

fruits = ["apple", "banana", "cherry"]
for fruit in fruits:
    print(f"I like {fruit}.")

Output:
I like apple.
I like banana.
I like cherry.

🔹 3. The range() Function

The range() function generates a sequence of numbers, often used to loop a specific number of times.

• range(stop): Numbers from 0 up to (but not including) stop.
• range(start, stop): Numbers from start up to (not including) stop.
• range(start, stop, step): Numbers from start up to stop, increasing by step.

Example:

for i in range(3): # Loop 3 times (0, 1, 2)
    print(f"Iteration {i}")

Output:
Iteration 0
Iteration 1
Iteration 2

🔹 4. break and continue Statements

• break: Stops the loop completely, even if the iterable hasn't finished.
• continue: Skips the rest of the current iteration and moves to the next.

Example (break):

for number in range(1, 6):
    if number == 4:
        break # Stop when number is 4
    print(number)

Output:
1
2
3

Example (continue):

for item in ["A", "B", "C", "D"]:
    if item == "C":
        continue # Skip 'C'
    print(item)

Output:
A
B
D

🎯 Today's Goal(What you should do)

✔️ Understand what for loops are
✔️ Iterate over lists, strings, and ranges (using your Python editor)
✔️ Use break and continue to control loop flow (using your Python editor)

🐍 Python If-Else Statements (Conditionals) 🤔

If-Else statements allow your program to make decisions and execute different code blocks based on conditions. They are fundamental for creating dynamic and responsive applications.

👉 Essential for controlling the flow of your program.

🔹 1. What are Conditional Statements?

They test a condition. If the condition is True, one block of code runs. If False, another block (or nothing) might run.

Example:

temperature = 25
if temperature > 20:
    print("It's warm!")

Output: It's warm!

🔹 2. The if Statement

The simplest conditional, executing code only when a condition is True.

Syntax:

if condition:
    # code to run if condition is True

Example:

age = 18
if age >= 18:
    print("You are an adult.")

Output: You are an adult.

🔹 3. The else Statement

Executes a block of code when the if condition is False.

Syntax:

if condition:
    # code if True
else:
    # code if False

Example:

score = 75
if score >= 90:
    print("Excellent!")
else:
    print("Good effort!")

Output: Good effort!

🔹 4. The elif (Else If) Statement

Allows you to check multiple conditions sequentially. If the first if is False, it checks elif, and so on.

Syntax:

if condition1:
    # code if condition1 is True
elif condition2:
    # code if condition2 is True
else:
    # code if all conditions are False

Example:

time = 14
if time < 12:
    print("Good morning!")
elif time < 18:
    print("Good afternoon!")
else:
    print("Good evening!")

Output: Good afternoon!

🔹 5. Short Hand If / Ternary Operator

A concise way to write simple if-else statements on a single line.

Example:

a = 10
b = 5
print("A is greater") if a > b else print("B is greater")

Output: A is greater

🎯 Today's Goal(What you should do)

✔️ Understand how to use if, elif, and else
✔️ Make your programs respond to different inputs
✔️ Use shorthand for simple conditions

👉 Conditional statements are the backbone of any interactive and logical Python program. It's crucial you understand them well.

Automating WhatsApp with Python

🐍 Python Dictionaries (Key-Value Pairs) 🔑

Dictionaries are unordered collections of data that store items in key-value pairs. They are incredibly powerful for organizing and quickly accessing related information.

👉 Ideal for representing real-world objects with unique identifiers (keys).

🔹 1. What is a Dictionary?

A mutable, unordered collection where each item has a unique key and an associated value. Defined by curly braces {}.

Example:

person = {"name": "Alice", "age": 30, "city": "New York"}
print(person)

Output: {'name': 'Alice', 'age': 30, 'city': 'New York'}

🔹 2. Accessing Dictionary Items

Access values using their associated key inside square brackets [] or with the .get() method.

Example:

student = {"id": 101, "name": "Bob", "grade": "A"}
print(student["name"])
print(student.get("grade"))

Output:
Bob
A

🔹 3. Adding and Modifying Items

To add a new item, assign a value to a new key. To modify, assign a new value to an existing key.

Example:

car = {"brand": "Ford", "model": "Mustang"}
car["year"] = 2020 # Add new item
car["model"] = "Explorer" # Modify existing item
print(car)

Output: {'brand': 'Ford', 'model': 'Explorer', 'year': 2020}

🔹 4. Removing Items

• del dict[key]: Removes the item with the specified key.
• .pop(key): Removes (and returns) the item with the specified key.
• .clear(): Empties the entire dictionary.

Example:

settings = {"theme": "dark", "sound": "on", "notifications": "off"}
del settings["sound"] # Remove by key
print(settings)
settings.pop("theme") # Also removes by key
print(settings)

Output:
{'theme': 'dark', 'notifications': 'off'}
{'notifications': 'off'}

🔹 5. Looping Through a Dictionary

You can loop through keys, values, or both (items).

Example:

for k, v in person.items(): # Loops through key-value pairs
    print(f"{k}: {v}")

Output:
name: Alice
age: 30
city: New York

🎯 Today's Goal(What you should do)

✔️ Understand how dictionaries store data in key-value pairs
✔️ Add, access, modify, and remove dictionary items
✔️ Iterate over keys, values, or items

🐍 Python Strings (Text Manipulation) 🔤

Strings are sequences of characters, used for handling text data. They are immutable, meaning once created, they cannot be changed directly. Python provides many built-in methods for working with strings.

👉 Essential for almost any program that interacts with text, from usernames to file paths.

🔹 1. What is a String?

A string is a sequence of characters, enclosed in single quotes '', double quotes "", or triple quotes """ """ for multi-line strings.

Example:

name = "Pythonista"
message = 'Hello, world!'
multiline = """This is
a multi-line
string."""
print(name)

Output: Pythonista

🔹 2. Accessing Characters (Indexing & Slicing)

• Indexing: Get a single character using its position (index starts at 0).
• Slicing: Get a sub-sequence of characters (a "slice") using [start:end]. The end index is exclusive.

Example:

word = "developer"
print(word[0])    # First character
print(word[3:7])  # Characters from index 3 up to (but not including) 7
print(word[-1])   # Last character

Output:
d
elop
r

🔹 3. String Concatenation & Length

• Concatenation: Joining strings using the + operator.
• len() function: Returns the number of characters in a string.

Example:

first = "Hello"
last = "World"
full_message = first + " " + last + "!"
print(full_message)
print(len(full_message))

Output:
Hello World!
12

🔹 4. Common String Methods

• .upper() / .lower(): Convert to uppercase/lowercase.
• .strip(): Removes leading/trailing whitespace.
• .replace(old, new): Replaces occurrences of a substring.
• .split(delimiter): Splits the string into a list of substrings.

Example:

text = "   Hello Python!   "
print(text.strip())
print("apple,banana,cherry".split(','))
print("Python".replace('o', '0'))

Output:
Hello Python!
['apple', 'banana', 'cherry']
Pyth0n

🔹 5. F-strings (Formatted String Literals)

A powerful and easy way to embed expressions inside string literals. Prefix the string with f or F.

Example:

item = "book"
price = 19.99
print(f"The {item} costs ${price:.2f}.") # .2f for 2 decimal places

Output: The book costs $19.99.

🎯 Today's Goal(What you should do)

✔️ Understand string immutability
✔️ Access characters and slice strings
✔️ Use common string methods for manipulation
✔️ Format strings with f-strings

60 Python Project Ideas (Beginner + Intermediate + Advanced)

🐍 Python Classes & Objects (OOP Basics) 🏗

Object-Oriented Programming (OOP) is a powerful paradigm where you design your applications using classes and objects. Classes serve as blueprints, and objects are instances of those blueprints.

👉 Essential for building structured, reusable, and scalable code in larger projects.

🔹 1. What is OOP?

OOP organizes code around objects rather than just functions and data. It focuses on concepts like encapsulation, inheritance, and polymorphism to make complex systems easier to manage.

🔹 2. Class vs. Object

• Class: A blueprint or a template for creating objects. It defines the properties (attributes) and behaviors (methods) that all objects of that type will have.
• Object: An instance of a class. It's a real-world entity created from the class blueprint.

Example: Class = Car, Object = "My blue Honda Civic"

🔹 3. Defining a Class

We use the class keyword to define a new class. Class names typically start with an uppercase letter.

Syntax:

class ClassName:
    # attributes (variables)
    # methods (functions)

Example:

class Dog:
    species = "Canis familiaris" # Class attribute

    def __init__(self, name, age): # Constructor method
        self.name = name # Instance attribute
        self.age = age   # Instance attribute

🔹 4. Creating an Object (Instantiating a Class)

To create an object from a class, you call the class name as if it were a function. This process is called instantiation.

Example:

my_dog = Dog("Buddy", 3) # Creating an object 'my_dog'
your_dog = Dog("Lucy", 5) # Creating another object 'your_dog'

🔹 5. Object Attributes & Methods

• Attributes: Variables that belong to an object (e.g., name, age). Accessed using dot notation: object.attribute.
• Methods: Functions that belong to an object (e.g., bark()). Defined inside the class and always take self as their first parameter.

Example:

class Dog:
    def __init__(self, name):
        self.name = name

    def bark(self): # A method
        print(f"{self.name} says Woof!")

my_dog = Dog("Rex")
print(my_dog.name) # Access attribute
my_dog.bark()      # Call method

Output:
Rex
Rex says Woof!

🎯 Today's Goal(What you should do)

✔️ Understand the concept of classes as blueprints and objects as instances
✔️ Define a simple class with attributes and methods
✔️ Create objects from a class

📚 The Algorithms: Python

This is the largest open-source collection of algorithms implemented exclusively in Python. It provides clean, well-documented, educational implementations of every major algorithm, from sorting to machine learning, actively maintained by a global community of 1,200+ contributors. No prerequisites required.

Key highlights:

🐍 Python-only focus - perfect for Python learners and developers
📈 219k stars, 50k forks - trusted by millions worldwide
🧠 Covers 50+ algorithmic domains: backtracking, dynamic programming, graphs, machine learning, neural networks, computer vision, cryptography, and more
🔄 Actively updated - last commit March 28, 2026
🎓 Educational purpose - implementations are clear and intended for learning, not just production

🔗 Link

@python_bds

🐍 Python Modules & Packages (Code Organization) 📂

Modules and packages help organize your Python code into reusable files and directories. They make your projects manageable, prevent name conflicts, and allow you to share code.

🔹 1. What are Modules?

A module is simply a Python file (.py extension) containing Python code (functions, classes, variables).

Example:
If you have my_math.py:

# my_math.py
def add(a, b):
    return a + b

🔹 2. Importing Modules

You use the import statement to bring functionality from one module into another.

Syntax:

import module_name
from module_name import specific_item
from module_name import * # Avoid this in large projects
import module_name as alias
Example:python
import my_math
print(my_math.add(5, 3)) # Access function using module_name.function

from my_math import add
print(add(10, 2)) # Access function directly

import math as m # Using an alias for built-in 'math' module
print(m.sqrt(16))

Output:
8
12
4.0

🔹 3. What are Packages?

A package is a way to organize related modules into a directory hierarchy. A directory becomes a Python package if it contains an __init__.py file (even if empty).

Example:

my_project/
├── main.py
└── my_package/
    ├── __init__.py
    ├── graphics.py
    └── sound.py

🔹 4. Importing from Packages

You import modules or specific items from modules within a package using dot notation.

Example (assuming my_package above):

# In main.py
from my_package import graphics
# Now you can use functions/classes from graphics.py like: graphics.draw_circle()

from my_package.sound import play_effect
# Now you can use play_effect() directly

🔹 5. Benefits of Modules & Packages

• Reusability: Write code once, use everywhere.
• Organization: Keeps related code together.
• Readability: Easier to understand structured code.
• Namespace management: Prevents variable/function name clashes.

🎯 Today's Goal (What you should do)

✔️ Understand what modules and packages are
✔️ Learn how to import functionality
✔️ Appreciate the benefits of code organization

Python Dictionaries

🐍 Python File I/O (Reading & Writing Files) 📝

File Input/Output (I/O) allows your Python programs to interact with external files, reading data from them or writing data to them. This is crucial for persistence, logging, and data processing.

🔹 1. Opening Files (open())

The open() function is used to open a file. It returns a file object.

Syntax:

file_object = open("filename.txt", "mode")

Common modes:
• "r": Read (default) - file must exist.
• "w": Write - creates a new file or overwrites an existing one.
• "a": Append - creates a new file or adds to the end of an existing one.
• "x": Exclusive creation - creates a new file, fails if it exists.

🔹 2. Reading from Files

Once opened in read mode, you can read content:
• .read(): Reads the entire file content as a single string.
• .readline(): Reads one line at a time.
• .readlines(): Reads all lines into a list of strings.

Example:

# Assuming 'data.txt' contains "Line 1\nLine 2\n"
file = open("data.txt", "r")
content = file.read()
print(content)
file.close() # Always close the file!

Output:
Line 1
Line 2

🔹 3. Writing to Files

Once opened in write ("w") or append ("a") mode, you can write content:
• .write(string): Writes a string to the file. Remember to add \n for new lines.

Example:

file = open("output.txt", "w")
file.write("Hello from Python!\n")
file.write("This is a new line.")
file.close()

(Creates/overwrites output.txt with the text.)

🔹 4. The with Statement (Best Practice!)

The with statement ensures files are automatically closed even if errors occur. This is the recommended way.

Syntax:

with open("filename.txt", "mode") as file_object:
    # perform file operations here
# File is automatically closed after this block
Example:python
with open("names.txt", "w") as f:
    f.write("Alice\nBob\n")

with open("names.txt", "r") as f:
    for line in f:
        print(line.strip()) # .strip() removes newline characters

Output:
Alice
Bob

🔹 5. File Modes (Binary vs. Text)

• Text mode (default): "r", "w", "a" - handles text encoding/decoding.
• Binary mode: "rb", "wb", "ab" - handles raw bytes, useful for images, executables, etc.

Example (Binary Write):

with open("data.bin", "wb") as f:
    f.write(b'\x01\x02\x03') # Writing bytes

🎯 Today's Goal

✔️ Understand how to open files in different modes
✔️ Read and write data to files
✔️ Master the with statement for safe file handling