Create lists in one line.

Basic List Comprehension

```python # Old way squares = [] for i in range(5): squares.append(i ** 2)

New way (list comprehension) squares = [i ** 2 for i in range(5)] print(squares) # [0, 1, 4, 9, 16] ```

With Condition

```python # Get even numbers evens = [i for i in range(10) if i % 2 == 0] print(evens) # [0, 2, 4, 6, 8]

Get names starting with 'A' names = ["Alice", "Bob", "Anna", "Charlie"] a_names = [name for name in names if name.startswith("A")] print(a_names) # ['Alice', 'Anna'] ```

Transform Data

```python cities = ["miami", "austin", "denver"] upper_cities = [city.upper() for city in cities] print(upper_cities) # ['MIAMI', 'AUSTIN', 'DENVER'] ```

Nested Comprehension

```python # Create 2D list matrix = [[i * j for j in range(3)] for i in range(3)] print(matrix) # [[0, 0, 0], [0, 1, 2], [0, 2, 4]] ```

Remember

- More readable for simple cases - Faster than loops - Don't overuse - keep it simple