Python For Absolute Beginners: Learn Python From Scratch

In this lecture we will learn how to install Python on windows computer.

Learn how to install Python IDE PyCharm on windows computer.

Learn how to install Python on Mac.

Learn how to install Python IDE PyCharm on Mac.

Learn how to install Python on a Linux computer.

Learn how to install Python IDE PyCharm on a Linux computer.

Refer to this lecture if you face any difficulties installing and setting up Python

The Python shell is an interactive command-line interface that allows you to execute Python code in real-time. It is a built-in tool that comes with every Python installation and is widely used by Python developers for testing small code snippets, debugging, and learning Python programming.

In this lecture, you will learn:

• What is a Python shell?

• How to use Python shell to run code interactively.

The Python shell is especially useful for beginners who want to quickly test Python code without creating a separate file. It provides a fast and interactive way to learn Python and execute Python commands line-by-line.

If you're new to Python programming or want to explore how to use the Python shell effectively, this lecture will give you a clear understanding of its features, use cases, and benefits.

By the end of this lecture, you'll be confident in using the Python shell to write and execute code quickly, making your Python learning journey smoother and more interactive.

In Python programming, mathematical operators (also known as arithmetic operators) are used to perform basic mathematical operations like addition, subtraction, multiplication, division, and more. These operators are essential for performing calculations and building logic in Python programs.

In this lecture, you will learn:

• What are mathematical operators in Python?

• Different types of arithmetic operators in Python such as:

  • Addition (+)

  • Subtraction (-)

  • Multiplication (*)

  • Division (/)

  • Floor Division (//)

Understanding mathematical operators in Python is crucial for performing mathematical calculations, building logic, and working with numeric data types. Whether you are working with simple calculations or complex mathematical problems, these operators make coding in Python easier and more efficient.

By the end of this lecture, you will have a strong understanding of arithmetic operators in Python and how to use them in real-world programming scenarios.

In Python programming, the exponent operator (**) and modulus operator (%) are two important mathematical operators used to perform specific calculations. The exponent operator is used to calculate the power of a number, while the modulus operator is used to find the remainder of a division operation. Understanding these operators is essential for performing mathematical calculations in Python.

In this lecture, you will learn:

• What is the exponent operator (**) in Python?

• How to use the exponent operator to calculate power in Python.

• What is the modulus operator (%) in Python?

• How to use the modulus operator to find the remainder of a division.

• Practical examples of exponent and modulus operators in Python.

In Python programming, a string is a sequence of characters enclosed in single quotes (' '), double quotes (" "), or triple quotes (''' ''' or """ """). Strings are widely used to represent text data in Python applications such as web development, data processing, and user input handling.

Sometimes, you may need to include special characters like newlines, tabs, quotes, or backslashes inside a string. This is where escape characters come into play. Escape characters in Python are represented by a backslash (\) followed by a special character, allowing you to include special symbols or formatting inside a string.

In this lecture, you will learn:

• What are strings in Python?

• How to create and use strings in Python.

• What are escape characters in Python?

By the end of this lecture, you will have a clear understanding of strings and escape characters in Python, enabling you to handle text data, format strings, and insert special characters effectively in your Python programs. This knowledge is crucial for building Python applications, working with user input, and formatting output.

In Python programming, accepting user input is an essential feature that allows you to take input from users during program execution. This is commonly used when building interactive applications, command-line tools, and user-driven software. In Python, the input() function is used to accept user input from the keyboard and store it in a variable for further processing.

In this lecture, you will learn:

• What is user input in Python?

• How to use the input() function to accept user input.

• Storing user input in a variable for processing.

• Converting user input to different data types like int, float, or string.

• Practical examples of accepting user input in Python.

By the end of this lecture, you will have a clear understanding of how to accept user input in Python and process it to build interactive Python applications. This knowledge is fundamental for working on real-world projects like web applications, data processing, and game development.

In Python programming, string concatenation is the process of joining two or more strings together to form a single string. This is commonly used when working with text data, user input, or displaying output in Python applications. Python provides several ways to concatenate strings, such as using the + operator, join() method, or f-strings (formatted strings).

In this lecture, you will learn:

• What is string concatenation in Python?

• How to concatenate strings using the + operator.

• Using join() method to concatenate strings.

• Using f-strings (formatted strings) for concatenation.

• Practical examples of string concatenation in Python.

By the end of this lecture, you will have a clear understanding of how to concatenate strings in Python using different methods. This knowledge is especially useful when working with user input, generating dynamic output, creating messages, and handling text data in Python applications.

In Python programming, data types define the type of value a variable can hold. Every piece of data you work with in Python, whether it's a number, text, list, or boolean value, has a specific data type. Understanding data types in Python is crucial for writing error-free and efficient code. Python provides several built-in data types to handle different types of data like numbers, text, collections, and logical values.

In this lecture, you will learn:

• What are data types in Python?

• Why are data types important in Python programming?

By the end of this lecture, you will have a strong understanding of Python data types and how to use them in real-world programming scenarios. This knowledge is fundamental when working with variables, user input, mathematical operations, and complex data structures in Python applications.

In Python programming, variables are used to store data values such as numbers, text, lists, or boolean values. A variable declaration in Python means creating a variable and assigning a value to it. Python makes it incredibly simple to declare and assign variables without explicitly specifying their data type, as Python is a dynamically typed language.

In this lecture, you will learn:

• What is a variable in Python?

• How to declare a variable in Python.

• How to assign a value to a variable using the assignment operator =.

• Rules for naming variables in Python.

• Best practices for declaring variables in Python.

• Examples of variable declaration and assignment in Python.

By the end of this lecture, you will have a clear understanding of how to declare and assign variables in Python. You will also learn best practices to follow while naming and using variables in your Python programs. Understanding variables is a fundamental concept in Python programming, as they are used in every Python application for storing and manipulating data.

In Python programming, naming conventions for variables are a set of rules and best practices that developers follow to name variables in a clear, readable, and meaningful way. Using proper variable naming conventions ensures that your code is easy to read, maintain, and understand. Python follows specific guidelines for naming variables, which are part of the PEP 8 (Python Enhancement Proposal) — the official style guide for Python code.

In this lecture, you will learn:

• What is a variable name in Python?

• Why are naming conventions important in Python programming?

• Rules for naming variables in Python.

• Best practices for writing clean and meaningful variable names.

• Different naming styles in Python (snake_case, camelCase, UPPERCASE, etc.).

• Examples of valid and invalid variable names in Python.

By the end of this lecture, you will have a clear understanding of Python variable naming conventions and how to follow best practices to write clean, readable, and professional code. This knowledge is crucial for writing scalable Python applications and collaborating with other developers.

In Python programming, operators are special symbols or keywords used to perform operations on variables and values. Python supports a wide range of operators to perform mathematical, logical, comparison, assignment, and bitwise operations. Understanding operators in Python is essential to perform calculations, data manipulation, decision-making, and control flow in your Python programs.

In this lecture, you will learn:

• What are operators in Python?

• Different types of operators in Python.

• *How to use mathematical operators (like +, -, , /, etc.) for arithmetic operations.

• Using comparison operators (==, !=, >, <, etc.) for comparing values.

• Working with logical operators (and, or, not) to combine conditions.

• Assignment operators (=, +=, -=, etc.) to assign and update values.

• Bitwise operators to perform binary operations.

• Membership and identity operators for checking values in collections.

• Practical examples of using Python operators in real-world scenarios.

By the end of this lecture, you will have a complete understanding of Python operators and how to use them to perform various operations in your Python programs. Operators are fundamental in writing logic, performing calculations, and building decision-making conditions in Python programming.

In Python programming, logical operators are used to combine multiple conditions and make logical decisions based on whether the conditions are True or False. Logical operators are extremely useful when you need to perform decision-making operations, such as executing a block of code based on multiple conditions. Python provides three main logical operators: and, or, not, which allow you to combine two or more conditions and get a boolean result (True or False).

In this lecture, you will learn:

• What are logical operators in Python?

• Why do we use logical operators in Python programming?

• Different types of logical operators:

  1. and operator – Returns True if both conditions are True.

  2. or operator – Returns True if at least one condition is True.

  3. not operator – Reverses the result of a condition.

• How to use logical operators with if-else statements.

• Practical examples of using logical operators in Python programs.

By the end of this lecture, you will have a complete understanding of Python logical operators and how to use them to combine multiple conditions for decision-making in your Python programs. Understanding logical operators is essential for building control flow, conditional statements, and real-world applications in Python.

In this lecture, you will learn how to write and execute your first Python program, commonly known as the "Hello World" program. This is the first step to getting started with Python programming, and it helps you set up your development environment to start writing Python code. We will use PyCharm, a popular Python IDE (Integrated Development Environment), to create and execute the Hello World program.

In this lecture, you will learn:

• How to open PyCharm IDE and set it up for Python development.

• How to create a new Python project in PyCharm.

• How to select a project interpreter (Python version) in PyCharm.

• How to change the theme (appearance) of PyCharm.

• How to write and execute the "Hello World" program in Python.

• Verify the output of your first Python program.

Steps to Write and Execute Hello World Program in PyCharm:

1. Open PyCharm IDE on your system.

2. Create a new Python project and name it something like "HelloWorldProject".

3. Select the Python interpreter (Python version installed on your system).

4. Change the theme of PyCharm if you prefer a different look.

5. Create a Python file, write your first Python code (print("Hello, World!")).

6. Run the Python file and see the output in the terminal.

By the end of this lecture, you will have:

• Successfully set up your development environment using PyCharm.

• Written and executed your first Python Hello World program.

• Understood the basic Python syntax for printing output.

• Gained confidence to write more Python code in upcoming lectures.

Starting with the Hello World program is a milestone for every Python beginner. It helps you ensure that your Python installation and setup are working perfectly and you are ready to explore Python programming.

In this lecture, you will learn how to write and execute your first Python program, commonly known as the "Hello World" program. This is the first step to getting started with Python programming, and it helps you set up your development environment to start writing Python code. We will use PyCharm, a popular Python IDE (Integrated Development Environment), to create and execute the Hello World program.

In this lecture, you will learn:

• How to open PyCharm IDE and set it up for Python development.

• How to create a new Python project in PyCharm.

• How to select a project interpreter (Python version) in PyCharm.

• How to change the theme (appearance) of PyCharm.

• How to write and execute the "Hello World" program in Python.

• Verify the output of your first Python program.

Steps to Write and Execute Hello World Program in PyCharm:

1. Open PyCharm IDE on your system.

2. Create a new Python project and name it something like "HelloWorldProject".

3. Select the Python interpreter (Python version installed on your system).

4. Change the theme of PyCharm if you prefer a different look.

5. Create a Python file, write your first Python code (print("Hello, World!")).

6. Run the Python file and see the output in the terminal.

By the end of this lecture, you will have:

• Successfully set up your development environment using PyCharm.

• Written and executed your first Python Hello World program.

• Understood the basic Python syntax for printing output.

• Gained confidence to write more Python code in upcoming lectures.

Starting with the Hello World program is a milestone for every Python beginner. It helps you ensure that your Python installation and setup are working perfectly and you are ready to explore Python programming.

In Python programming, comments are lines of text added to the code to explain its functionality, making it easier to understand, debug, and maintain. Comments are not executed by the Python interpreter, which means they do not affect the output of the program. Writing clear and meaningful comments is a best practice in Python programming, especially when working on large projects or collaborating with other developers.

In this lecture, you will learn:

• What are comments in Python?

• Why are comments important in Python programming?

• How to add single-line comments in Python using the # symbol.

• How to write multi-line comments in Python using triple quotes (''' or """).

• Best practices for writing clear and concise comments.

• Practical examples of using comments in Python code.

By the end of this lecture, you will have a clear understanding of how to add comments in Python and why they are important for writing clean, understandable, and maintainable code. You will also learn best practices for adding comments that enhance the readability of your Python code.

✅ Key Takeaway: Always use comments in Python to make your code self-explanatory, especially when working on complex logic, algorithms, or collaborating with other developers.

In Python programming, you can create interactive programs by accepting user input from the keyboard using the built-in input() function. This allows you to collect data from the user, such as numbers, text, or any other information, and then perform various operations with it. One of the most common tasks in Python is to accept two numbers from the user and add them together to display the result. This is a fundamental concept when learning Python programming.

In this lecture, you will learn:

• How to accept user input in Python using the input() function.

• How to accept numeric input (integers or floats) from the user.

• How to convert user input from string to integer or float using int() or float() functions.

• How to add two numbers in Python and display the result.

• Practical examples of accepting user input and performing addition.

Explanation:

• The input() function is used to accept input from the user.

• The int() function is used to convert the input from a string to an integer.

• The two numbers are then added using the + operator, and the result is displayed using the print() function.

✅ Key Takeaway:

• The input() function is a powerful tool in Python for accepting user input.

• Always convert input to an appropriate data type (like int or float) when performing mathematical operations.

• This concept is widely used in building interactive Python programs, calculators, and data-driven applications.

In Python programming, you can easily create a username and email address by accepting user input using the input() function. This is a fundamental concept when building user registration systems, login systems, or sign-up forms in Python applications. By collecting user information such as first name, last name, or domain name, you can generate a unique username and email address dynamically using Python.

In this lecture, you will learn:

• How to accept user input for username and email creation in Python.

• How to combine user input (like first name, last name) to generate a username.

• How to create a custom email address using Python string concatenation.

• How to display the generated username and email to the user.

• Practical examples of creating a username and email in Python.

✅ Key Takeaway:

• You can easily generate a username and email in Python by combining user input.

• This concept is widely used in creating sign-up forms, registration systems, and login pages in Python web applications.

• You can extend this logic to validate email formats, check for existing usernames, or connect to a database for storing user information.

In Python programming, comparing two user input strings is a common task, especially when building login systems, user authentication, or text comparison applications. Using Python's comparison operators such as == (equal to) and != (not equal to), you can easily compare two strings entered by the user to check if they are identical or different. This is particularly useful when validating usernames, passwords, email addresses, or any text-based input in Python applications.

In this lecture, you will learn:

• How to accept string input from the user in Python.

• How to compare two strings using comparison operators (== and !=).

• How to perform case-insensitive string comparison using Python's lower() or upper() methods.

• Practical examples of comparing user strings in Python.

• Best practices for string comparison in Python.

✅ Key Takeaway:

• You can easily compare two user input strings in Python using comparison operators (==, !=).

• For case-insensitive comparison, use Python's built-in lower() or upper() methods.

• This concept is crucial for building user authentication systems, input validation, and form handling in Python.

In Python programming, you can easily create a Simple Interest Calculator using user input and basic arithmetic operations.

In this lecture, you will learn:

• How to accept user input (principal, rate, time) in Python.

• How to perform arithmetic calculations in Python.

• How to calculate Simple Interest using Python's arithmetic operators.

• How to display the result to the user.

• Practical example of building a Simple Interest Calculator in Python.

✅ Key Takeaway:

• You can build a Simple Interest Calculator in Python using just basic arithmetic operations.

• Accepting user input for principal, rate, and time makes the program interactive.

• This logic is commonly used in finance, loan calculators, and banking applications.

• You can further enhance this program by adding compound interest calculation, EMI calculators, or investment growth calculators.

Python programming, f-strings (formatted string literals) provide a simple and clean way to format strings dynamically. Introduced in Python 3.6, f-strings allow you to directly embed variables, expressions, or function outputs inside a string using curly braces {} prefixed with the letter f or F. This makes it extremely easy to concatenate text and variables without using the traditional + operator or cumbersome format() method.

F-strings are widely used in dynamic content generation, displaying user input, generating dynamic output, and creating formatted messages in Python.

In this lecture, you will learn:

• What are f-strings in Python.

• How to use f-strings to format strings in Python.

• How to insert variables, expressions, and function outputs inside f-strings.

• Advantages of using f-strings over traditional string concatenation.

• Practical examples of using f-strings in Python.

✅ Key Takeaway:

• F-strings in Python are the most efficient and clean way to format strings dynamically.

• You can insert variables, expressions, and function outputs directly inside the f-string using {}.

• F-strings make your code more readable, faster, and simpler.

• They are widely used in web development, data processing, and dynamic output generation.

n Python programming, you can easily build a BMI (Body Mass Index) Calculator to calculate a person's BMI based on their weight (in kilograms) and height (in meters). BMI is a standard metric used to determine whether a person has a healthy body weight in proportion to their height.

1. How to accept user input for weight and height in Python.

2. How to apply the BMI formula in Python.

3. How to categorize BMI results (Underweight, Normal, Overweight, Obese).

4. How to display the result in a user-friendly format.

5. Practical example of building a BMI Calculator in Python.

✅ Key Takeaway:

• A BMI Calculator in Python is a simple and practical project that involves taking user input, performing calculations, and displaying results.

• You can further extend this project by adding height input in feet/inches, ideal weight range, or even creating a web-based BMI calculator using Python frameworks like Flask/Django.

• This project is commonly used in healthcare, fitness, and medical applications.

In Python programming, a list is one of the most commonly used data structures that allows you to store multiple items in a single variable. Lists in Python are ordered, mutable (changeable), and allow duplicate values. They are widely used when you need to store collections of data, such as a list of numbers, names, items, or objects.

A list in Python can contain different data types such as integers, strings, floats, booleans, and even other lists. You can easily access, modify, delete, and perform various operations on lists using Python built-in functions and methods.

In this lecture, you will learn:

• ✅ What are lists in Python.

• ✅ How to create a list in Python.

• ✅ How to access elements from a list.

• ✅ How to modify, add, and remove items from a list.

• ✅ Common list methods and their uses.

• ✅ Iterating through a list using loops.

• ✅ Practical examples of using lists in Python.

✅ Key Takeaway:

• Lists in Python are extremely useful when you need to store and manage collections of data.

• You can easily create, access, modify, and delete elements in a list.

• Lists are widely used in web development, data science, machine learning, game development, and many other fields.

• Mastering Python lists is essential for becoming a proficient Python developer.

In Python programming, a list is a powerful and flexible data structure that allows you to store multiple items in a single variable. One of the unique features of lists in Python is that they can hold different data types within the same list. This means you can store integers, floats, strings, booleans, and even other lists in a single Python list.

In this lecture, you will learn:

• ✅ How to create a list with different data types in Python.

• ✅ How to access and manipulate elements with different data types.

• ✅ How to use nested lists in Python.

• ✅ Practical examples of storing multiple data types in a Python list.

✅ Key Takeaway:

• Lists in Python are highly versatile and allow you to store different data types like integers, strings, floats, booleans, and nested lists.

• You can access, modify, add, or remove elements from a mixed data type list in Python.

• Understanding how to store and manage different data types in Python lists is essential for working with real-world data in Python applications.

In Python programming, lists are one of the most commonly used data structures to store multiple items in a single variable. Python provides a powerful feature known as negative indexing that allows you to access elements from the end of the list. This means instead of starting the index from 0 (left to right), you can start from -1 (right to left) using negative indexing in Python lists.

✅ Why Use Negative Indexing in Python?

• Easier access to the last elements of the list without calculating the length.

• Convenient when working with dynamic data where the length of the list is unknown.

• Helps you quickly retrieve the last few elements of a list.

✅ Why Is Negative Indexing Useful in Python Lists?

1. Quick Access to Last Element: Instead of writing my_list[len(my_list)-1], you can simply use my_list[-1].

2. Flexible Data Handling: When working with dynamic data like user inputs, web scraped data, or file data, negative indexing simplifies element access.

3. Avoid Length Calculation: It eliminates the need to calculate the length of the list for accessing the last element.

✅ Key Points to Remember About Negative Indexing in Python:

1. -1 refers to the last element.

2. -2 refers to the second last element.

3. -len(list) refers to the first element of the list.

4. Negative indexing is useful for dynamic data or when you don’t know the exact size of the list.

✅ Common Use Cases of Negative Indexing in Python Lists:

1. Accessing the last element of a list without calculating the length.

2. Looping through a list in reverse order.

3. Modifying the last few elements of a list.

4. Accessing data from nested lists using negative indexes.