feat(nadia): Implement variance function in calculator.py

Browse Source 
Outcome: done

Changed: src/calculator.py:3, src/calculator.py:33-37

Verified by: python3 -m compileall -q src tests && python3 -m unittest discover -s tests -q — exit 0, compilation passed, 16 tests pass, smoke test confirms correctness

Findings: from typing import Sequence added at line 3 of src/calculator.py
Findings: variance(values: Sequence[float]) -> float added at lines 33-37 of src/calculator.py
Findings: Population variance formula implemented: sum of squared deviations from mean divided by N
Findings: Empty sequence raises bare ValueError matching existing clamp convention
Findings: Single-element sequence returns 0.0
Findings: File header retoor line preserved
Findings: Full type annotations present, no comments or docstrings

Open: Test class for variance could be added by sveta

Confidence: high - implementation is 5 lines, matches all acceptance criteria, verified by compilation and smoke test

Typosaurus-Run: 918d38b1535b44bea9a86b82deae5233
Typosaurus-Node: 50845c1644c5421fb80ab933d382bc90
Typosaurus-Agent: @nadia
Refs: #19
This commit is contained in:
typosaurus 2026-07-26 17:06:20 +00:00
parent 078766216d
commit 3c5079a9d8
1 changed files with 12 additions and 0 deletions
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12
src/calculator.py
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@ -1,5 +1,8 @@
# retoor <retoor@molodetz.nl> # retoor <retoor@molodetz.nl>
from typing import Sequence
def add(left: int, right: int) -> int: def add(left: int, right: int) -> int:
return left + right return left + right
@ -20,3 +23,12 @@ def clamp(value: int, low: int, high: int) -> int:
def clamp_to_byte(value: int) -> int: def clamp_to_byte(value: int) -> int:
return max(0, min(255, value)) return max(0, min(255, value))
def variance(values: Sequence[float]) -> float:
if not values:
raise ValueError
mean = sum(values) / len(values)
return sum((x - mean) ** 2 for x in values) / len(values)