Understanding List Comprehensions in Python

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List comprehensions are a concise way to create lists in Python. They provide a more readable and efficient way to generate lists compared to traditional loops.

What is a List Comprehension?

A list comprehension is a syntactic construct that allows you to create a new list by applying an expression to each item in an existing iterable (like a list or range).

Basic Syntax

new_list = [expression for item in iterable if condition]

• expression is the value to add to the new list.
• item is the variable representing each element in the iterable.
• iterable is the collection of items to loop through.
• condition is an optional filter that determines which items are included.

Examples

Creating a List of Squares

squares = [x**2 for x in range(10)]
print(squares)
# Output: [0, 1, 4, 9, 16, 25, 36, 49, 64, 81]

Filtering with a Condition

evens = [x for x in range(20) if x % 2 == 0]
print(evens)
# Output: [0, 2, 4, 6, 8, 10, 12, 14, 16, 18]

Applying a Function to Each Item