How to Use List Comprehensions in Python?

List comprehensions provide a concise way to create lists in Python. They consist of brackets containing an expression followed by a for clause, and can include optional if clauses.

Basic Syntax

new_list = [expression for item in iterable]

Example: Creating a List of Squares

squares = [x**2 for x in range(1, 6)]
print(squares)  # Output: [1, 4, 9, 16, 25]

Adding an if Condition

You can include an if condition to filter items:

even_squares = [x**2 for x in range(1, 11) if x % 2 == 0]
print(even_squares)  # Output: [4, 16, 36, 64, 100]

Nesting List Comprehensions

Create a list of tuples:

pairs = [(x, y) for x in range(3) for y in range(3)]
print(pairs)

Using Functions in Expressions

def double(x):
    return x * 2

doubled = [double(x) for x in range(5)]
print(doubled)  # Output: [0, 2, 4, 6, 8]

Conclusion

List comprehensions offer a readable and efficient way to create lists. They are a powerful feature in Python that can simplify your code.