Introduction to Python Programming (Class X)

1. What is Python?

Python is a high-level, easy-to-learn programming language used in:

Web development
Artificial Intelligence
Data Science
Game development
Automation

Features of Python

Simple syntax
Easy to read and write
Platform independent
Large number of libraries

2. Tokens in Python

Definition

Tokens are the smallest units in a Python program.

Types of Tokens

Keywords
Identifiers
Literals
Operators
Punctuators

Example

a = 10

Here:

a → Identifier
= → Operator
10 → Literal

3. Variables

Definition

In Python, a variable is a symbolic name that acts as a reference or pointer to an object stored in memory.

Example

name = "Rahul"
age = 15

4. Rules for Naming Variables/Identifiers

Valid Rules

Must start with a letter or _
Cannot start with a number
Cannot contain spaces and special symbols like @#$%^&*
Cannot use keywords

Valid Examples

student_name
_marks
age1

Invalid Examples

1name
student name
class

5. Data Types in Python

Data Type	Example
Integer (`int`)	`10`
Float (`float`)	`3.14`
String (`str`)	`"Hello"`
Boolean (`bool`)	`True`
List	`[1,2,3]`
Tuple	`(1,2,3)`
Set	`{1,2,3}`
Dictionary	`{"a":1}`

6. Operators in Python

Operators are special symbols or keywords. Operators are used to perform operations on variables and values.

A. Arithmetic Operators

Operator	Meaning	Example
`+`	Addition	`5+2`
`-`	Subtraction	`5-2`
`*`	Multiplication	`5*2`
`/`	Division	`5/2`
`%`	Modulus	`5%2`
`//`	Floor Division	`5//2`
`**`	Exponent	`2**3`

Example:

a = 10
b = 3
print(a+b)
print(a%b)

B. Assignment Operators

Operator	Example
`=`	`a = 5`
`+=`	`a += 2`
`-=`	`a -= 2`
`*=`	`a *= 2`

C. Comparison Operators

Operator	Meaning
`==`	Equal
`!=`	Not equal
`>`	Greater than
`<`	Less than
`>=`	Greater than equal
`<=`	Less than equal

Example:

print(5 > 2)

D. Logical Operators

Operator	Meaning
`and`	Both conditions true
`or`	Any one condition true
`not`	Reverse result

Example:

print(True and False)

E. Identity Operators

Operator	Meaning
`is`	Same object
`is not`	Different object

F. Membership Operators

Operator	Meaning
`in`	Present
`not in`	Not present

Example:

a = [1,2,3]
print(2 in a)

G. Bitwise Operators

Operator	Meaning
`&`	AND
`	`
`^`	XOR
`~`	NOT
`<<`	Left Shift
`>>`	Right Shift

7. Comments in Python

Comments are notes written in the source code that the interpreter completely ignores during execution. They are used to explain code, make it more readable and understable.

Single-line Comment

# This is a comment

Multi-line Comment

"""
This is
multi-line comment
"""

8. Control Structures

Control structures decide the flow of execution.

Types:

Conditional Statements
Loops

9. Conditional Statements

A. if Statement

age = 18

if age >= 18:
    print("Eligible")

B. if-else Statement

num = 5

if num % 2 == 0:
    print("Even")
else:
    print("Odd")

C. if-elif-else Statement

marks = 85

if marks >= 90:
    print("A")
elif marks >= 75:
    print("B")
else:
    print("C")

D. Nested if

num = 10

if num > 0:
    if num % 2 == 0:
        print("Positive Even")

10. Loops in Python

Loops are used to repeat statements. In Python, loops are control structures used to repeat a block of code multiple times. There are two primary types of loops: for loops and while loops.

A. for Loop

for i in range(5):
    print(i)

Output:

B. while Loop

i = 1

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

11. Built-in Functions

Python’s built-in functions are pre-defined tools available in the interpreter without requiring any import statements. Some important buil-in functions are print(), input(), range()

A. print()

Used to display output on the screen.

print("Hello")

B. input()

Used to take input from user.

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

C. range()

Used in loops to generate sequence.

for i in range(1,6):
    print(i)

12. Lists in Python

Definition

List is an ordered, mutable collection.

fruits = ["apple", "banana", "mango"]

A. Modify Element

fruits[1] = "orange"
print(fruits)

B. Add Element

append()

fruits.append("grapes")

insert()

fruits.insert(1, "kiwi")

C. Remove Element

remove()

fruits.remove("apple")

pop()

fruits.pop()

D. Sorting List

numbers = [4,1,3,2]
numbers.sort()
print(numbers)

13. Tuple

Definition

Tuple is an ordered and immutable collection.

t = (1,2,3)

Properties of Tuple

Ordered
Immutable
Allows duplicate values

Accessing Tuple Elements

print(t[0])

14. Sets in Python

Definition

Set is an unordered collection of unique elements.

s = {1,2,3}

Properties of Set

Unordered
No duplicate values
Mutable

A. Adding Elements

s.add(4)

B. Removing Elements

s.remove(2)

C. Union

Combines elements of two sets.

a = {1,2,3}
b = {3,4,5}

print(a.union(b))

D. intersection_update()

Updates common elements.

a = {1,2,3}
b = {2,3,4}

a.intersection_update(b)
print(a)

E. intersection()

Returns common elements.

a = {1,2,3}
b = {2,3,4}

print(a.intersection(b))

15. Dictionary in Python

Definition

Dictionary stores data in key-value pairs.

student = {
    "name":"Rahul",
    "marks":90
}

Properties of Dictionary

Stores key-value pairs
Mutable
Keys must be unique

A. get()

print(student.get("name"))

B. keys()

print(student.keys())

C. values()

print(student.values())

D. items()

print(student.items())

E. update()

student.update({"age":15})

F. pop()

student.pop("marks")

16. Python Libraries

Libraries provide extra functionality.

A. NumPy

NumPy is used for numerical calculations and arrays.

Example:

import numpy as np

arr = np.array([1,2,3])
print(arr)

B. Pandas

Pandas is used for data analysis.

Example:

import pandas as pd

C. OpenCV

OpenCV is used for image processing and computer vision.

Example:

import cv2

D. Matplotlib

Matplotlib is used for graphs and charts.

Example:

import matplotlib.pyplot as plt

17. Practice Questions

Very Short Answer

What is a variable?
Name two data types.
What is a comment?

Short Answer

Differentiate between list and tuple.
Explain if-else statement with example.
Write properties of set.

Programs

Write a program to check even or odd.
Write a program to print numbers from 1 to 10.
Create a list and sort it.
Create a dictionary of student details.

18. Summary

In this chapter you learned:

Tokens and variables
Data types
Operators
Conditional statements and loops
Lists, tuples, sets, dictionaries
Built-in functions
Python libraries

Python is beginner-friendly and widely used in modern technology fields.