Dict / Set Comprehensions

Python List Comprehension Cheat Sheet

List comprehensions are Python's most distinctive feature: they pack filter, map, and flatten into a single expression. This cheat sheet covers the basic map-and-filter form, the nested form for cartesian products and matrix flattening, and the conditional-expression form that branches inside the output. Each pattern shows up many times per Python file in real codebases.

Python Dict Comprehension Cheat Sheet

Dict comprehensions build mappings without explicit loops, the same way list comprehensions build lists. They are the right tool for inverting a dict, projecting a list of tuples into a key-value map, and filtering an existing dict by predicate. This snippet covers the basic build form, the invert and merge patterns, and the filtering form for trimming an existing dict.

Python Set Comprehension Patterns

Set comprehensions are the underused sibling of list and dict comprehensions. They build deduplicated collections in one line and excel at unique-by-key extraction, set algebra, and quick membership filters. This snippet covers the basic uniqueness pattern, the unique-by-projection form for objects, and set algebra (intersection, difference) expressed as comprehensions.