🟢 Beginner · Lesson 16

List, Set and Dictionary Comprehension

List, Set और Dictionary Comprehension

What is List Comprehension?

List Comprehension means list comprehension creates a new list in a compact and readable way using an expression and a loop.

In real programs, this topic helps in filtering lists quickly. Learn the idea first, then type the program yourself and compare the output.

💡 At a Glance

Point	Details
Course Area	Advanced Python Professional concepts used to make code reusable, clean and project-ready.
Main Use	filtering lists quickly
Example File	`list-comprehension.py`
Practice Focus	Run, change values, and explain the output line by line.

Why should you learn this?

It is useful for filtering lists quickly.
It connects with transforming data in one line.
It improves your ability to read, write and debug Python programs.

Important Terms

These terms are used directly in this lesson. Understand them before memorising the code.

Term	Meaning
compact loop	compact loop is an important term in this topic.
filter	Keeps only items that satisfy a condition.
expression	A value-producing part of code, such as x * 2.
new list	new list is an important term in this topic.
readability	The quality of code being easy to understand for humans.

Syntax / Basic Pattern

The simple pattern is: prepare data, apply the concept, then show the result.

Basic Pattern

numbers = [1, 2, 3, 4, 5, 6]
squares = [n * n for n in numbers]
even_squares = [n * n for n in numbers if n % 2 == 0]
print(squares)
print(even_squares)

Complete Example Program

Python – list-comprehension.py

numbers = [1, 2, 3, 4, 5, 6]

squares = [n * n for n in numbers]
even_squares = [n * n for n in numbers if n % 2 == 0]

print(squares)
print(even_squares)

Expected Output

[1, 4, 9, 16, 25, 36] [4, 16, 36]

Program Explanation

numbers = [1, 2, 3, 4, 5, 6] stores a value in numbers.
squares = [n * n for n in numbers] stores a value in squares.
even_squares = [n * n for n in numbers if n % 2 == 0] performs the next step of the program logic.
print(squares) displays information or calculated result on the screen.
print(even_squares) displays information or calculated result on the screen.

Where will you use it?

Filtering lists quickly.
Transforming data in one line.
Writing concise readable code.

Common Mistakes

Making code complex when a simple function or class is enough.
Not handling possible errors or edge cases.
Mixing project dependencies instead of using a virtual environment.

Practice Tasks

Type the program in list-comprehension.py and run it.
Change input values or sample data and observe the new output.
Create one example related to filtering lists quickly.
Write 5 lines explaining the logic in your own words.

Summary

List Comprehension is not a theory-only topic. You should be able to explain the meaning, write the example, run it successfully, and use it in a small practical program.

List Comprehension क्या है?

List Comprehension ka matlab hai: List comprehension creates a new list in a compact and readable way using an expression and a loop. Simple words me, ye topic practical Python programs likhne me direct use hota hai.

Is topic ko sirf definition ke liye nahi, balki filtering lists quickly jaise real examples ke liye practice karein.

यह क्यों सीखना जरूरी है?

Ye filtering lists quickly me kaam aata hai.
Ye transforming data in one line se bhi connected hai.
Isse aap code ka output aur errors better samajh paate hain.

Important Terms

Term	Meaning
compact loop	compact loop is an important term in this topic.
filter	Keeps only items that satisfy a condition.
expression	A value-producing part of code, such as x * 2.
new list	new list is an important term in this topic.
readability	The quality of code being easy to understand for humans.

Syntax / Basic Pattern

Basic idea: pehle data तैयार करें, phir Python logic apply करें, aur finally result display करें.

Basic Pattern

numbers = [1, 2, 3, 4, 5, 6]
squares = [n * n for n in numbers]
even_squares = [n * n for n in numbers if n % 2 == 0]
print(squares)
print(even_squares)

Complete Example Program

Python – list-comprehension.py

numbers = [1, 2, 3, 4, 5, 6]

squares = [n * n for n in numbers]
even_squares = [n * n for n in numbers if n % 2 == 0]

print(squares)
print(even_squares)

Expected Output

[1, 4, 9, 16, 25, 36] [4, 16, 36]

Program Explanation

numbers = [1, 2, 3, 4, 5, 6] stores a value in numbers.
squares = [n * n for n in numbers] stores a value in squares.
even_squares = [n * n for n in numbers if n % 2 == 0] performs the next step of the program logic.
print(squares) displays information or calculated result on the screen.
print(even_squares) displays information or calculated result on the screen.

Practical Uses

Filtering lists quickly.
Transforming data in one line.
Writing concise readable code.

Common Mistakes

Making code complex when a simple function or class is enough.
Not handling possible errors or edge cases.
Mixing project dependencies instead of using a virtual environment.

Practice Tasks

Program ko list-comprehension.py file me type karke run karein.
Values change karke output compare karein.
filtering lists quickly par ek छोटा example banayen.
Logic ko apne words me 5 lines me likhein.

सारांश

List Comprehension ko tab complete maanenge jab aap iska meaning, example, output aur practical use clearly explain kar saken.

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