python 21 lines · 5 steps

Multi-key sorting patterns in Python

Three ways to sort lists of dicts on multiple fields, including mixed ascending and descending order.

Explained by highlit
Intermediate sorting tuple-keys itemgetter stable-sort
1from operator import itemgetter
2 
3 
4def sort_employees(employees):
5 return sorted(
6 employees,
7 key=itemgetter("department", "last_name", "first_name"),
8 )
9 
10 
11def sort_by_salary_then_tenure(employees):
12 return sorted(
13 employees,
14 key=lambda e: (-e["salary"], e["years"], e["last_name"]),
15 )
16 
17 
18def sort_with_mixed_directions(records):
19 ordered = sorted(records, key=itemgetter("name"))
20 ordered.sort(key=itemgetter("priority"), reverse=True)
21 return ordered
01 / 01
STEP 01

Walkthrough

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Three takeaways
  1. 1A tuple key sorts by its first element, breaking ties with each following element in turn.
  2. 2Negating a numeric key inverts its direction while keeping other keys ascending in a single pass.
  3. 3Python's stable sort lets you layer sorts: sort by the least significant key first, most significant last.

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