Python List Comprehensions

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List Comprehensions

Transform loops into concise expressions without sacrificing readability.

Learn syntax patternsAvoid anti-patterns

Syntax

numbers = [n for n in range(10)]
even_squares = [n * n for n in range(10) if n % 2 == 0]
matrix = [[col for col in row] for row in grid]

• Format: [expression for item in iterable if condition].
• Nest comprehensions carefully; readability matters.

Best practices

• Keep comprehensions single-purpose. If you need multiple statements, use a loop.
• Use generator expressions (expression for ...) when you only need iteration, not a full list.
• Pair with functions like sum, any, all for quick aggregations.

Next up in your learning path

List slicing

Combine comprehensions with slicing for advanced patterns.

Companion

Nested lists

Apply comprehensions to multi-dimensional data.

Practice

Set/dict comprehensions

Extend the concept to sets and dictionaries.

Reference