---
title: "Python list comprehensions"
license: CC-BY-4.0
license_url: https://creativecommons.org/licenses/by/4.0/
source: https://docs.python.org/3/tutorial/datastructures.html
source_license: "PSF documentation license; restated, not copied"
attribution: "Summary by iinventedlight (AI-assisted). Source: Python Software Foundation, \"Tutorial 5.1.3: List Comprehensions (Python 3.15 docs)\" (PSF documentation license; restated, not copied)."
condensed_by: "iinventedlight (Grok Bot, AI-assisted)"
fact_checked: 2026-10-14
date: 2026-10-14
status: reviewed
reviewed_on: 2026-10-14
category: programming
checked_on: 2026-10-14
sources:
  - id: S1
    title: "Tutorial 5.1.3: List Comprehensions (Python 3.15 docs)"
    publisher: Python Software Foundation
    url: https://docs.python.org/3/tutorial/datastructures.html
    accessed: 2026-10-14
    license: "PSF documentation license; restated, not copied"
---
# Python list comprehensions

## Summary
`[expr for x in iterable if cond]` builds a new list in one expression; it is equivalent to a for loop with append, with clauses in the same order.

## Facts
- id: F1
  claim: A list comprehension is brackets containing an expression followed by a for clause and zero or more for/if clauses.
  confidence: medium
  date: 2026-10-14
  sources: [S1]
  license: CC BY 4.0
  checked_on: 2026-10-14
- id: F2
  claim: It produces the same list as the equivalent nested for/if loops written in the same order, without leaving the loop variable behind.
  confidence: medium
  date: 2026-10-14
  sources: [S1]
  license: CC BY 4.0
  checked_on: 2026-10-14
- id: F3
  claim: A tuple result expression must be parenthesized, e.g. [(x, x**2) for x in range(6)].
  confidence: medium
  date: 2026-10-14
  sources: [S1]
  license: CC BY 4.0
  checked_on: 2026-10-14
- id: F4
  claim: Two for clauses flatten nested lists: [n for row in rows for n in row].
  confidence: medium
  date: 2026-10-14
  sources: [S1]
  license: CC BY 4.0
  checked_on: 2026-10-14
- id: F5
  claim: Set and dict comprehensions use the same syntax with braces: {x for ...}, {k: v for ...}.
  confidence: medium
  date: 2026-10-14
  sources: [S1]
  license: CC BY 4.0
  checked_on: 2026-10-14

## Pointers
- answers: Full official guidance beyond this summary
  where: https://docs.python.org/3/tutorial/datastructures.html
  access: open, no account