Class 11 Artificial Intelligence – Unit 3: Python Programming | Complete Notes

Unit 3: Python Programming

1. Learning Outcomes

By the end of this unit, students will be able to:

• Explain the basics of the Python programming language.
• Write Python programs using basic programming concepts and tokens.
• Use selective statements to control program flow.
• Use iterative statements for repetitive tasks.
• Understand and use essential Python libraries such as NumPy, Pandas and Scikit-learn.
• Apply Python programming to solve simple real-life problems.

2. Introduction to Python

Python is a general-purpose, high-level programming language. It is one of the most widely used programming languages in the fields of Artificial Intelligence, Machine Learning, Data Science and Web Development.

Why is it called Python?

The name Python was inspired by the BBC comedy series "Monty Python's Flying Circus".

Key Features of Python

Feature	Meaning
Easy to read and learn	Python has a simple and readable syntax that is close to human language.
Interpreted	Python programs are executed line by line by an interpreter.
Free and Open Source	Python is freely available and its source code can be accessed and modified.
Platform Independent	Python programs can run on operating systems such as Windows, macOS and Linux.
Versatile	Python is used in AI, data science, web development and many other areas.

3. Getting Started: Tools and Editors

Python code can be written and executed using different development environments and editors.

Jupyter Notebook

Jupyter Notebook is an interactive web application that allows users to create and share documents containing live Python code, explanations and visualizations.

It is widely used in Data Science, Machine Learning and Artificial Intelligence.

Anaconda

Anaconda is a popular Python distribution that comes with several important libraries, including NumPy and Pandas.

Other Python Tools and Editors

• IDLE
• PyCharm
• Spyder
• Google Colab

4. Python Tokens

Tokens are the smallest individual units of a Python program that are recognized by the interpreter.

4.1 Keywords

Keywords are reserved words that have a special meaning in Python. They cannot be used as ordinary variable or function names.

Examples:

if, else, for, import, while, True, False

4.2 Identifiers

Identifiers are names given to variables, functions, classes and other programming elements.

Rules for identifiers:

• An identifier cannot start with a digit.
• It can contain letters, digits and underscore (_).
• Special characters are not allowed.
• Python keywords cannot be used as identifiers.

Identifier	Validity	Reason
student_name	Valid	Contains letters and underscore.
1st_place	Invalid	An identifier cannot start with a digit.

4.3 Literals

Literals are fixed/raw data values directly specified in a program.

Type	Example
String Literal	"Hello"
Numeric Literal	45
Boolean Literal	True

4.4 Operators

Operators are symbols or keywords used to perform operations on values or operands.

Operator Type	Operators	Purpose
Arithmetic	+, -, *, /, %	Perform mathematical operations.
Relational	==, !=, <, >, <=, >=	Compare two values.
Logical	and, or, not	Combine or modify conditions.
Assignment	=, +=, -=	Assign or update values.

4.5 Punctuators

Punctuators are symbols used to organize the structure of Python code.

Examples: :, ( ), [ ], { }, ,, .

5. Data Types and Variables

What are Data Types?

Data types classify data items and tell the computer what kind of operations can be performed on them.

What is a Variable?

A variable is a named label used to store a value that can be processed during program execution.

Example:

age = 16
name = "Ria"

Here, age and name are variables.

Standard Data Types in Python

Category	Data Type	Description	Example
Numbers	Integer	Whole numbers.	count = 10
Numbers	Floating Point	Numbers containing decimal values.	price = 99.99
Boolean	Boolean	Represents either True or False.	is_passed = True
Sequences	String	Text enclosed within quotes; immutable.	name = "Ria"
Sequences	List	Ordered and changeable collection.	tasks = ["eat", "code"]
Sequences	Tuple	Ordered collection that cannot be changed.	coords = (12.5, 77.3)
Mappings	Dictionary	Collection of key-value pairs enclosed in curly brackets.	{'One': 1}

Type Casting

Type casting is the explicit conversion of one data type into another.

Example:

age = int(input("Enter your age: "))

Here, the value entered through input() is converted into an integer using int().

6. Input and Output

print() Function

The print() function is used to display output on the screen.

print("Welcome to Python")
print(25)

input() Function

The input() function is used to receive data from the user. By default, the value returned by input() is a string.

name = input("Enter your name: ")
print(name)

age = int(input("Enter your age: "))

7. Control Flow Statements

Control flow statements determine the order in which statements in a program are executed.

They can broadly be divided into:

1. Selection Statements
2. Looping Statements

7.1 Selection Statements

Selection statements are used to make decisions and execute specific blocks of code depending on conditions.

if Statement

The if statement executes a block of code when the specified condition is true.

marks = 80

if marks >= 40:
    print("Pass")

if-else Statement

The if-else statement provides two alternatives: one block executes when the condition is true and another when it is false.

marks = 35

if marks >= 40:
    print("Pass")
else:
    print("Fail")

if-elif-else Ladder

An if-elif-else ladder is used when multiple conditions need to be checked.

choice = input("Enter your choice: ")

if choice == "Veg":
    print("Vegetarian Menu")
elif choice == "Non-veg":
    print("Non-Vegetarian Menu")
else:
    print("Mixed Menu")

7.2 Looping Statements

Looping statements are used to execute a block of code repeatedly.

for Loop

A for loop is generally used to iterate over a sequence or a range of values.

Example: Printing the first ten even natural numbers

for i in range(2, 21, 2):
    print(i)

while Loop

A while loop executes a block of code as long as a specified condition remains true.

count = 1

while count <= 5:
    print(count)
    count = count + 1

8. CSV Files

CSV stands for Comma Separated Values. A CSV file stores tabular data such as numbers and text in plain-text form.

Uses of CSV Files

• Storing tabular data.
• Importing data into spreadsheets.
• Exporting data from databases.
• Preparing datasets for AI and Machine Learning analysis.

9. Essential Python Libraries for AI

Python provides powerful libraries that make it easier to work with numerical data, datasets and Machine Learning algorithms.

9.1 NumPy

NumPy is used for numerical computing and mathematical operations. Its primary data structure is the ndarray.

Key use: Working efficiently with numerical data and arrays.

9.2 Pandas

Pandas is an important Python library used for data manipulation and analysis.

Pandas uses DataFrames to work with multiple columns of data simultaneously.

Example:

import pandas as pd

data = pd.read_csv("admission.csv")

Such data can then be analyzed to study student marks or other information.

9.3 Scikit-learn

Scikit-learn (Sklearn) is a powerful library used to implement Machine Learning algorithms.

It supports important Machine Learning tasks such as classification and regression.

Library	Main Purpose	Important Structure / Feature
NumPy	Numerical computing and mathematical operations	ndarray
Pandas	Data manipulation and analysis	DataFrame
Scikit-learn	Machine Learning	Classification, Regression and other ML algorithms

10. Practical Applications of Python

Python can be used to solve a variety of real-life problems by combining variables, operators, input/output and control statements.

10.1 Tipper Program

A tipper program can calculate the tip amount based on a customer's total bill. For example, the program may calculate 15% and 20% tips.

bill = float(input("Enter total bill: "))

tip15 = bill * 15 / 100
tip20 = bill * 20 / 100

print("15% Tip =", tip15)
print("20% Tip =", tip20)

10.2 Service Reminder

A service reminder can check the kilometer reading of a vehicle and determine whether servicing is required.

km = int(input("Enter kilometer reading: "))

if km >= 15000:
    print("Service is required")
else:
    print("Service is not required")

10.3 Salary Calculator

A salary calculator can calculate net salary by adding allowances such as HRA and DA and subtracting deductions such as PF.

basic = float(input("Enter basic salary: "))
hra = float(input("Enter HRA: "))
da = float(input("Enter DA: "))
pf = float(input("Enter PF: "))

net_salary = basic + hra + da - pf

print("Net Salary =", net_salary)

11. Quick Revision Table

Concept	Key Point to Remember
Python	General-purpose, high-level programming language.
Creator	Guido van Rossum
First Released	1991
Python Name	Inspired by "Monty Python's Flying Circus".
Token	Smallest individual unit recognized by the Python interpreter.
Variable	Named label used to store a value.
input()	Accepts user input and returns a string by default.
print()	Displays output on the screen.
if	Used for decision-making.
for	Used to iterate over a sequence or range.
while	Repeats statements while a condition remains true.
CSV	Comma Separated Values.
NumPy	Numerical computing; uses ndarray.
Pandas	Data manipulation and analysis; uses DataFrame.
Scikit-learn	Machine Learning algorithms such as classification and regression.

12. Important Exam Points

13. One-Minute Concept Map