https://github.com/python/cpython/commit/f0a8bc737ab2f04d4196eee154cb1e17e26ad585 commit: f0a8bc737ab2f04d4196eee154cb1e17e26ad585 branch: main author: Raymond Hettinger <[email protected]> committer: gpshead <[email protected]> date: 2025-11-14T23:25:45Z summary:
gh-140938: Raise ValueError for infinite inputs to stdev/pstdev (GH-141531) Raise ValueError for infinite inputs to stdev/pstdev --- Co-authored-by: Gregory P. Smith <[email protected]> Co-authored-by: Bénédikt Tran <[email protected]> files: A Misc/NEWS.d/next/Library/2025-11-13-14-51-30.gh-issue-140938.kXsHHv.rst M Lib/statistics.py M Lib/test/test_statistics.py diff --git a/Lib/statistics.py b/Lib/statistics.py index 3d805cb073987d..26cf925529ea60 100644 --- a/Lib/statistics.py +++ b/Lib/statistics.py @@ -619,9 +619,14 @@ def stdev(data, xbar=None): if n < 2: raise StatisticsError('stdev requires at least two data points') mss = ss / (n - 1) + try: + mss_numerator = mss.numerator + mss_denominator = mss.denominator + except AttributeError: + raise ValueError('inf or nan encountered in data') if issubclass(T, Decimal): - return _decimal_sqrt_of_frac(mss.numerator, mss.denominator) - return _float_sqrt_of_frac(mss.numerator, mss.denominator) + return _decimal_sqrt_of_frac(mss_numerator, mss_denominator) + return _float_sqrt_of_frac(mss_numerator, mss_denominator) def pstdev(data, mu=None): @@ -637,9 +642,14 @@ def pstdev(data, mu=None): if n < 1: raise StatisticsError('pstdev requires at least one data point') mss = ss / n + try: + mss_numerator = mss.numerator + mss_denominator = mss.denominator + except AttributeError: + raise ValueError('inf or nan encountered in data') if issubclass(T, Decimal): - return _decimal_sqrt_of_frac(mss.numerator, mss.denominator) - return _float_sqrt_of_frac(mss.numerator, mss.denominator) + return _decimal_sqrt_of_frac(mss_numerator, mss_denominator) + return _float_sqrt_of_frac(mss_numerator, mss_denominator) ## Statistics for relations between two inputs ############################# diff --git a/Lib/test/test_statistics.py b/Lib/test/test_statistics.py index 8250b0aef09aec..677a87b51b9192 100644 --- a/Lib/test/test_statistics.py +++ b/Lib/test/test_statistics.py @@ -2005,7 +2005,6 @@ def test_iter_list_same(self): expected = self.func(data) self.assertEqual(self.func(iter(data)), expected) - class TestPVariance(VarianceStdevMixin, NumericTestCase, UnivariateTypeMixin): # Tests for population variance. def setUp(self): @@ -2113,6 +2112,14 @@ def test_center_not_at_mean(self): self.assertEqual(self.func(data), 2.5) self.assertEqual(self.func(data, mu=0.5), 6.5) + def test_gh_140938(self): + # Inputs with inf/nan should raise a ValueError + with self.assertRaises(ValueError): + self.func([1.0, math.inf]) + with self.assertRaises(ValueError): + self.func([1.0, math.nan]) + + class TestSqrtHelpers(unittest.TestCase): def test_integer_sqrt_of_frac_rto(self): diff --git a/Misc/NEWS.d/next/Library/2025-11-13-14-51-30.gh-issue-140938.kXsHHv.rst b/Misc/NEWS.d/next/Library/2025-11-13-14-51-30.gh-issue-140938.kXsHHv.rst new file mode 100644 index 00000000000000..bd3044002a2d54 --- /dev/null +++ b/Misc/NEWS.d/next/Library/2025-11-13-14-51-30.gh-issue-140938.kXsHHv.rst @@ -0,0 +1,2 @@ +The :func:`statistics.stdev` and :func:`statistics.pstdev` functions now raise a +:exc:`ValueError` when the input contains an infinity or a NaN. _______________________________________________ Python-checkins mailing list -- [email protected] To unsubscribe send an email to [email protected] https://mail.python.org/mailman3//lists/python-checkins.python.org Member address: [email protected]
