https://github.com/python/cpython/commit/b0a2c0fa83f9b79616ccf451687096542de... commit: b0a2c0fa83f9b79616ccf451687096542de1e6f8 branch: master author: Raymond Hettinger <rhettinger@users.noreply.github.com> committer: GitHub <noreply@github.com> date: 2019-04-29T23:47:33-07:00 summary: bpo-36018: Test idempotence. Test two methods against one-another. (GH-13021) files: M Lib/test/test_statistics.py diff --git a/Lib/test/test_statistics.py b/Lib/test/test_statistics.py index 0a967055f0fe..903ee8f343cb 100644 --- a/Lib/test/test_statistics.py +++ b/Lib/test/test_statistics.py @@ -2158,6 +2158,20 @@ def test_specific_cases(self): result = quantiles(map(datatype, data), n=n) self.assertTrue(all(type(x) == datatype) for x in result) self.assertEqual(result, list(map(datatype, expected))) + # Quantiles should be idempotent + if len(expected) >= 2: + self.assertEqual(quantiles(expected, n=n), expected) + # Cross-check against other methods + if len(data) >= n: + # After end caps are added, method='inclusive' should + # give the same result as method='exclusive' whenever + # there are more data points than desired cut points. + padded_data = [min(data) - 1000] + data + [max(data) + 1000] + self.assertEqual( + quantiles(data, n=n), + quantiles(padded_data, n=n, method='inclusive'), + (n, data), + ) # Invariant under tranlation and scaling def f(x): return 3.5 * x - 1234.675 @@ -2219,6 +2233,15 @@ def f(x): actual = quantiles(statistics.NormalDist(), n=n, method="inclusive") self.assertTrue(all(math.isclose(e, a, abs_tol=0.0001) for e, a in zip(expected, actual))) + # Whenever n is smaller than the number of data points, running + # method='inclusive' should give the same result as method='exclusive' + # after the two included extreme points are removed. + data = [random.randrange(10_000) for i in range(501)] + actual = quantiles(data, n=32, method='inclusive') + data.remove(min(data)) + data.remove(max(data)) + expected = quantiles(data, n=32) + self.assertEqual(expected, actual) def test_equal_inputs(self): quantiles = statistics.quantiles