10. List comprehensions in Python

10. What are list comprehensions and why do we use them, if at all?

✅ What Are List Comprehensions in Python?

A list comprehension is a concise, readable way to create a new list by applying an expression to each item in an iterable (like a list, range, etc.), optionally filtering with a condition.

🧱 Basic Syntax:

[expression for item in iterable if condition]

🧠 Why Use Them?

• More concise than for loops.
• More readable for simple operations.
• Faster than equivalent loops in many cases.

🔁 Example vs. Traditional Loop:

✅ List comprehension:

squares = [x**2 for x in range(10)]

❌ Equivalent with loop:

squares = []
for x in range(10):
    squares.append(x**2)

🎯 With Condition:

even_squares = [x**2 for x in range(10) if x % 2 == 0]

🧱 Nested List Comprehension:

matrix = [[i * j for j in range(3)] for i in range(3)]
# Output: [[0, 0, 0], [0, 1, 2], [0, 2, 4]]

⚠️ When Not to Use:

• When the logic is too complex — use a regular loop for clarity.
• When you need to perform multiple actions in the loop body.

Summary: