diff options
Diffstat (limited to 'Lib/test/test_statistics.py')
| -rw-r--r-- | Lib/test/test_statistics.py | 467 |
1 files changed, 443 insertions, 24 deletions
diff --git a/Lib/test/test_statistics.py b/Lib/test/test_statistics.py index 0089ae8dc60..6cac7095c2d 100644 --- a/Lib/test/test_statistics.py +++ b/Lib/test/test_statistics.py @@ -21,6 +21,10 @@ import statistics # === Helper functions and class === +def sign(x): + """Return -1.0 for negatives, including -0.0, otherwise +1.0.""" + return math.copysign(1, x) + def _nan_equal(a, b): """Return True if a and b are both the same kind of NAN. @@ -264,6 +268,13 @@ class NumericTestCase(unittest.TestCase): # === Test the helpers === # ======================== +class TestSign(unittest.TestCase): + """Test that the helper function sign() works correctly.""" + def testZeroes(self): + # Test that signed zeroes report their sign correctly. + self.assertEqual(sign(0.0), +1) + self.assertEqual(sign(-0.0), -1) + # --- Tests for approx_equal --- @@ -659,7 +670,7 @@ class DocTests(unittest.TestCase): @unittest.skipIf(sys.flags.optimize >= 2, "Docstrings are omitted with -OO and above") def test_doc_tests(self): - failed, tried = doctest.testmod(statistics) + failed, tried = doctest.testmod(statistics, optionflags=doctest.ELLIPSIS) self.assertGreater(tried, 0) self.assertEqual(failed, 0) @@ -702,9 +713,9 @@ class ExactRatioTest(unittest.TestCase): def test_decimal(self): D = Decimal _exact_ratio = statistics._exact_ratio - self.assertEqual(_exact_ratio(D("0.125")), (125, 1000)) - self.assertEqual(_exact_ratio(D("12.345")), (12345, 1000)) - self.assertEqual(_exact_ratio(D("-1.98")), (-198, 100)) + self.assertEqual(_exact_ratio(D("0.125")), (1, 8)) + self.assertEqual(_exact_ratio(D("12.345")), (2469, 200)) + self.assertEqual(_exact_ratio(D("-1.98")), (-99, 50)) def test_inf(self): INF = float("INF") @@ -743,18 +754,18 @@ class ExactRatioTest(unittest.TestCase): class DecimalToRatioTest(unittest.TestCase): - # Test _decimal_to_ratio private function. + # Test _exact_ratio private function. def test_infinity(self): # Test that INFs are handled correctly. inf = Decimal('INF') - self.assertEqual(statistics._decimal_to_ratio(inf), (inf, None)) - self.assertEqual(statistics._decimal_to_ratio(-inf), (-inf, None)) + self.assertEqual(statistics._exact_ratio(inf), (inf, None)) + self.assertEqual(statistics._exact_ratio(-inf), (-inf, None)) def test_nan(self): # Test that NANs are handled correctly. for nan in (Decimal('NAN'), Decimal('sNAN')): - num, den = statistics._decimal_to_ratio(nan) + num, den = statistics._exact_ratio(nan) # Because NANs always compare non-equal, we cannot use assertEqual. # Nor can we use an identity test, as we don't guarantee anything # about the object identity. @@ -767,30 +778,30 @@ class DecimalToRatioTest(unittest.TestCase): for d in numbers: # First test positive decimals. assert d > 0 - num, den = statistics._decimal_to_ratio(d) + num, den = statistics._exact_ratio(d) self.assertGreaterEqual(num, 0) self.assertGreater(den, 0) # Then test negative decimals. - num, den = statistics._decimal_to_ratio(-d) + num, den = statistics._exact_ratio(-d) self.assertLessEqual(num, 0) self.assertGreater(den, 0) def test_negative_exponent(self): # Test result when the exponent is negative. - t = statistics._decimal_to_ratio(Decimal("0.1234")) - self.assertEqual(t, (1234, 10000)) + t = statistics._exact_ratio(Decimal("0.1234")) + self.assertEqual(t, (617, 5000)) def test_positive_exponent(self): # Test results when the exponent is positive. - t = statistics._decimal_to_ratio(Decimal("1.234e7")) + t = statistics._exact_ratio(Decimal("1.234e7")) self.assertEqual(t, (12340000, 1)) def test_regression_20536(self): # Regression test for issue 20536. # See http://bugs.python.org/issue20536 - t = statistics._decimal_to_ratio(Decimal("1e2")) + t = statistics._exact_ratio(Decimal("1e2")) self.assertEqual(t, (100, 1)) - t = statistics._decimal_to_ratio(Decimal("1.47e5")) + t = statistics._exact_ratio(Decimal("1.47e5")) self.assertEqual(t, (147000, 1)) @@ -971,6 +982,301 @@ class ConvertTest(unittest.TestCase): self.assertTrue(_nan_equal(x, nan)) +class FailNegTest(unittest.TestCase): + """Test _fail_neg private function.""" + + def test_pass_through(self): + # Test that values are passed through unchanged. + values = [1, 2.0, Fraction(3), Decimal(4)] + new = list(statistics._fail_neg(values)) + self.assertEqual(values, new) + + def test_negatives_raise(self): + # Test that negatives raise an exception. + for x in [1, 2.0, Fraction(3), Decimal(4)]: + seq = [-x] + it = statistics._fail_neg(seq) + self.assertRaises(statistics.StatisticsError, next, it) + + def test_error_msg(self): + # Test that a given error message is used. + msg = "badness #%d" % random.randint(10000, 99999) + try: + next(statistics._fail_neg([-1], msg)) + except statistics.StatisticsError as e: + errmsg = e.args[0] + else: + self.fail("expected exception, but it didn't happen") + self.assertEqual(errmsg, msg) + + +class Test_Product(NumericTestCase): + """Test the private _product function.""" + + def test_ints(self): + data = [1, 2, 5, 7, 9] + self.assertEqual(statistics._product(data), (0, 630)) + self.assertEqual(statistics._product(data*100), (0, 630**100)) + + def test_floats(self): + data = [1.0, 2.0, 4.0, 8.0] + self.assertEqual(statistics._product(data), (8, 0.25)) + + def test_overflow(self): + # Test with floats that overflow. + data = [1e300]*5 + self.assertEqual(statistics._product(data), (5980, 0.6928287951283193)) + + def test_fractions(self): + F = Fraction + data = [F(14, 23), F(69, 1), F(665, 529), F(299, 105), F(1683, 39)] + exp, mant = statistics._product(data) + self.assertEqual(exp, 0) + self.assertEqual(mant, F(2*3*7*11*17*19, 23)) + self.assertTrue(isinstance(mant, F)) + # Mixed Fraction and int. + data = [3, 25, F(2, 15)] + exp, mant = statistics._product(data) + self.assertEqual(exp, 0) + self.assertEqual(mant, F(10)) + self.assertTrue(isinstance(mant, F)) + + def test_decimal(self): + D = Decimal + data = [D('24.5'), D('17.6'), D('0.025'), D('1.3')] + expected = D('14.014000') + self.assertEqual(statistics._product(data), (0, expected)) + + def test_mixed_decimal_float(self): + # Test that mixed Decimal and float raises. + self.assertRaises(TypeError, statistics._product, [1.0, Decimal(1)]) + self.assertRaises(TypeError, statistics._product, [Decimal(1), 1.0]) + + +@unittest.skipIf(True, "FIXME: tests known to fail, see issue #27181") +class Test_Nth_Root(NumericTestCase): + """Test the functionality of the private _nth_root function.""" + + def setUp(self): + self.nroot = statistics._nth_root + + # --- Special values (infinities, NANs, zeroes) --- + + def test_float_NAN(self): + # Test that the root of a float NAN is a float NAN. + NAN = float('nan') + for n in range(2, 9): + with self.subTest(n=n): + result = self.nroot(NAN, n) + self.assertTrue(math.isnan(result)) + + def test_decimal_QNAN(self): + # Test the behaviour when taking the root of a Decimal quiet NAN. + NAN = decimal.Decimal('nan') + with decimal.localcontext() as ctx: + ctx.traps[decimal.InvalidOperation] = 1 + self.assertRaises(decimal.InvalidOperation, self.nroot, NAN, 5) + ctx.traps[decimal.InvalidOperation] = 0 + self.assertTrue(self.nroot(NAN, 5).is_qnan()) + + def test_decimal_SNAN(self): + # Test that taking the root of a Decimal sNAN always raises. + sNAN = decimal.Decimal('snan') + with decimal.localcontext() as ctx: + ctx.traps[decimal.InvalidOperation] = 1 + self.assertRaises(decimal.InvalidOperation, self.nroot, sNAN, 5) + ctx.traps[decimal.InvalidOperation] = 0 + self.assertRaises(decimal.InvalidOperation, self.nroot, sNAN, 5) + + def test_inf(self): + # Test that the root of infinity is infinity. + for INF in (float('inf'), decimal.Decimal('inf')): + for n in range(2, 9): + with self.subTest(n=n, inf=INF): + self.assertEqual(self.nroot(INF, n), INF) + + # FIXME: need to check Decimal zeroes too. + def test_zero(self): + # Test that the root of +0.0 is +0.0. + for n in range(2, 11): + with self.subTest(n=n): + result = self.nroot(+0.0, n) + self.assertEqual(result, 0.0) + self.assertEqual(sign(result), +1) + + # FIXME: need to check Decimal zeroes too. + def test_neg_zero(self): + # Test that the root of -0.0 is -0.0. + for n in range(2, 11): + with self.subTest(n=n): + result = self.nroot(-0.0, n) + self.assertEqual(result, 0.0) + self.assertEqual(sign(result), -1) + + # --- Test return types --- + + def check_result_type(self, x, n, outtype): + self.assertIsInstance(self.nroot(x, n), outtype) + class MySubclass(type(x)): + pass + self.assertIsInstance(self.nroot(MySubclass(x), n), outtype) + + def testDecimal(self): + # Test that Decimal arguments return Decimal results. + self.check_result_type(decimal.Decimal('33.3'), 3, decimal.Decimal) + + def testFloat(self): + # Test that other arguments return float results. + for x in (0.2, Fraction(11, 7), 91): + self.check_result_type(x, 6, float) + + # --- Test bad input --- + + def testBadOrderTypes(self): + # Test that nroot raises correctly when n has the wrong type. + for n in (5.0, 2j, None, 'x', b'x', [], {}, set(), sign): + with self.subTest(n=n): + self.assertRaises(TypeError, self.nroot, 2.5, n) + + def testBadOrderValues(self): + # Test that nroot raises correctly when n has a wrong value. + for n in (1, 0, -1, -2, -87): + with self.subTest(n=n): + self.assertRaises(ValueError, self.nroot, 2.5, n) + + def testBadTypes(self): + # Test that nroot raises correctly when x has the wrong type. + for x in (None, 'x', b'x', [], {}, set(), sign): + with self.subTest(x=x): + self.assertRaises(TypeError, self.nroot, x, 3) + + def testNegativeError(self): + # Test negative x raises correctly. + x = random.uniform(-20.0, -0.1) + assert x < 0 + for n in range(3, 7): + with self.subTest(x=x, n=n): + self.assertRaises(ValueError, self.nroot, x, n) + # And Decimal. + self.assertRaises(ValueError, self.nroot, Decimal(-27), 3) + + # --- Test that nroot is never worse than calling math.pow() --- + + def check_error_is_no_worse(self, x, n): + y = math.pow(x, n) + with self.subTest(x=x, n=n, y=y): + err1 = abs(self.nroot(y, n) - x) + err2 = abs(math.pow(y, 1.0/n) - x) + self.assertLessEqual(err1, err2) + + def testCompareWithPowSmall(self): + # Compare nroot with pow for small values of x. + for i in range(200): + x = random.uniform(1e-9, 1.0-1e-9) + n = random.choice(range(2, 16)) + self.check_error_is_no_worse(x, n) + + def testCompareWithPowMedium(self): + # Compare nroot with pow for medium-sized values of x. + for i in range(200): + x = random.uniform(1.0, 100.0) + n = random.choice(range(2, 16)) + self.check_error_is_no_worse(x, n) + + def testCompareWithPowLarge(self): + # Compare nroot with pow for largish values of x. + for i in range(200): + x = random.uniform(100.0, 10000.0) + n = random.choice(range(2, 16)) + self.check_error_is_no_worse(x, n) + + def testCompareWithPowHuge(self): + # Compare nroot with pow for huge values of x. + for i in range(200): + x = random.uniform(1e20, 1e50) + # We restrict the order here to avoid an Overflow error. + n = random.choice(range(2, 7)) + self.check_error_is_no_worse(x, n) + + # --- Test for numerically correct answers --- + + def testExactPowers(self): + # Test that small integer powers are calculated exactly. + for i in range(1, 51): + for n in range(2, 16): + if (i, n) == (35, 13): + # See testExpectedFailure35p13 + continue + with self.subTest(i=i, n=n): + x = i**n + self.assertEqual(self.nroot(x, n), i) + + def testExpectedFailure35p13(self): + # Test the expected failure 35**13 is almost exact. + x = 35**13 + err = abs(self.nroot(x, 13) - 35) + self.assertLessEqual(err, 0.000000001) + + def testOne(self): + # Test that the root of 1.0 is 1.0. + for n in range(2, 11): + with self.subTest(n=n): + self.assertEqual(self.nroot(1.0, n), 1.0) + + def testFraction(self): + # Test Fraction results. + x = Fraction(89, 75) + self.assertEqual(self.nroot(x**12, 12), float(x)) + + def testInt(self): + # Test int results. + x = 276 + self.assertEqual(self.nroot(x**24, 24), x) + + def testBigInt(self): + # Test that ints too big to convert to floats work. + bignum = 10**20 # That's not that big... + self.assertEqual(self.nroot(bignum**280, 280), bignum) + # Can we make it bigger? + hugenum = bignum**50 + # Make sure that it is too big to convert to a float. + try: + y = float(hugenum) + except OverflowError: + pass + else: + raise AssertionError('hugenum is not big enough') + self.assertEqual(self.nroot(hugenum, 50), float(bignum)) + + def testDecimal(self): + # Test Decimal results. + for s in '3.759 64.027 5234.338'.split(): + x = decimal.Decimal(s) + with self.subTest(x=x): + a = self.nroot(x**5, 5) + self.assertEqual(a, x) + a = self.nroot(x**17, 17) + self.assertEqual(a, x) + + def testFloat(self): + # Test float results. + for x in (3.04e-16, 18.25, 461.3, 1.9e17): + with self.subTest(x=x): + self.assertEqual(self.nroot(x**3, 3), x) + self.assertEqual(self.nroot(x**8, 8), x) + self.assertEqual(self.nroot(x**11, 11), x) + + +class Test_NthRoot_NS(unittest.TestCase): + """Test internals of the nth_root function, hidden in _nroot_NS.""" + + def test_class_cannot_be_instantiated(self): + # Test that _nroot_NS cannot be instantiated. + # It should be a namespace, like in C++ or C#, but Python + # lacks that feature and so we have to make do with a class. + self.assertRaises(TypeError, statistics._nroot_NS) + + # === Tests for public functions === class UnivariateCommonMixin: @@ -1082,13 +1388,13 @@ class UnivariateTypeMixin: Not all tests to do with types need go in this class. Only those that rely on the function returning the same type as its input data. """ - def test_types_conserved(self): - # Test that functions keeps the same type as their data points. - # (Excludes mixed data types.) This only tests the type of the return - # result, not the value. + def prepare_types_for_conservation_test(self): + """Return the types which are expected to be conserved.""" class MyFloat(float): def __truediv__(self, other): return type(self)(super().__truediv__(other)) + def __rtruediv__(self, other): + return type(self)(super().__rtruediv__(other)) def __sub__(self, other): return type(self)(super().__sub__(other)) def __rsub__(self, other): @@ -1098,9 +1404,14 @@ class UnivariateTypeMixin: def __add__(self, other): return type(self)(super().__add__(other)) __radd__ = __add__ + return (float, Decimal, Fraction, MyFloat) + def test_types_conserved(self): + # Test that functions keeps the same type as their data points. + # (Excludes mixed data types.) This only tests the type of the return + # result, not the value. data = self.prepare_data() - for kind in (float, Decimal, Fraction, MyFloat): + for kind in self.prepare_types_for_conservation_test(): d = [kind(x) for x in data] result = self.func(d) self.assertIs(type(result), kind) @@ -1275,12 +1586,16 @@ class AverageMixin(UnivariateCommonMixin): for x in (23, 42.5, 1.3e15, Fraction(15, 19), Decimal('0.28')): self.assertEqual(self.func([x]), x) + def prepare_values_for_repeated_single_test(self): + return (3.5, 17, 2.5e15, Fraction(61, 67), Decimal('4.9712')) + def test_repeated_single_value(self): # The average of a single repeated value is the value itself. - for x in (3.5, 17, 2.5e15, Fraction(61, 67), Decimal('4.9712')): + for x in self.prepare_values_for_repeated_single_test(): for count in (2, 5, 10, 20): - data = [x]*count - self.assertEqual(self.func(data), x) + with self.subTest(x=x, count=count): + data = [x]*count + self.assertEqual(self.func(data), x) class TestMean(NumericTestCase, AverageMixin, UnivariateTypeMixin): @@ -1304,7 +1619,7 @@ class TestMean(NumericTestCase, AverageMixin, UnivariateTypeMixin): self.assertEqual(self.func(data), 22.015625) def test_decimals(self): - # Test mean with ints. + # Test mean with Decimals. D = Decimal data = [D("1.634"), D("2.517"), D("3.912"), D("4.072"), D("5.813")] random.shuffle(data) @@ -1379,6 +1694,94 @@ class TestMean(NumericTestCase, AverageMixin, UnivariateTypeMixin): self.assertEqual(statistics.mean([tiny]*n), tiny) +class TestHarmonicMean(NumericTestCase, AverageMixin, UnivariateTypeMixin): + def setUp(self): + self.func = statistics.harmonic_mean + + def prepare_data(self): + # Override mixin method. + values = super().prepare_data() + values.remove(0) + return values + + def prepare_values_for_repeated_single_test(self): + # Override mixin method. + return (3.5, 17, 2.5e15, Fraction(61, 67), Decimal('4.125')) + + def test_zero(self): + # Test that harmonic mean returns zero when given zero. + values = [1, 0, 2] + self.assertEqual(self.func(values), 0) + + def test_negative_error(self): + # Test that harmonic mean raises when given a negative value. + exc = statistics.StatisticsError + for values in ([-1], [1, -2, 3]): + with self.subTest(values=values): + self.assertRaises(exc, self.func, values) + + def test_ints(self): + # Test harmonic mean with ints. + data = [2, 4, 4, 8, 16, 16] + random.shuffle(data) + self.assertEqual(self.func(data), 6*4/5) + + def test_floats_exact(self): + # Test harmonic mean with some carefully chosen floats. + data = [1/8, 1/4, 1/4, 1/2, 1/2] + random.shuffle(data) + self.assertEqual(self.func(data), 1/4) + self.assertEqual(self.func([0.25, 0.5, 1.0, 1.0]), 0.5) + + def test_singleton_lists(self): + # Test that harmonic mean([x]) returns (approximately) x. + for x in range(1, 101): + self.assertEqual(self.func([x]), x) + + def test_decimals_exact(self): + # Test harmonic mean with some carefully chosen Decimals. + D = Decimal + self.assertEqual(self.func([D(15), D(30), D(60), D(60)]), D(30)) + data = [D("0.05"), D("0.10"), D("0.20"), D("0.20")] + random.shuffle(data) + self.assertEqual(self.func(data), D("0.10")) + data = [D("1.68"), D("0.32"), D("5.94"), D("2.75")] + random.shuffle(data) + self.assertEqual(self.func(data), D(66528)/70723) + + def test_fractions(self): + # Test harmonic mean with Fractions. + F = Fraction + data = [F(1, 2), F(2, 3), F(3, 4), F(4, 5), F(5, 6), F(6, 7), F(7, 8)] + random.shuffle(data) + self.assertEqual(self.func(data), F(7*420, 4029)) + + def test_inf(self): + # Test harmonic mean with infinity. + values = [2.0, float('inf'), 1.0] + self.assertEqual(self.func(values), 2.0) + + def test_nan(self): + # Test harmonic mean with NANs. + values = [2.0, float('nan'), 1.0] + self.assertTrue(math.isnan(self.func(values))) + + def test_multiply_data_points(self): + # Test multiplying every data point by a constant. + c = 111 + data = [3.4, 4.5, 4.9, 6.7, 6.8, 7.2, 8.0, 8.1, 9.4] + expected = self.func(data)*c + result = self.func([x*c for x in data]) + self.assertEqual(result, expected) + + def test_doubled_data(self): + # Harmonic mean of [a,b...z] should be same as for [a,a,b,b...z,z]. + data = [random.uniform(1, 5) for _ in range(1000)] + expected = self.func(data) + actual = self.func(data*2) + self.assertApproxEqual(actual, expected) + + class TestMedian(NumericTestCase, AverageMixin): # Common tests for median and all median.* functions. def setUp(self): @@ -1600,6 +2003,22 @@ class TestMedianGrouped(TestMedian): data = [220, 220, 240, 260, 260, 260, 260, 280, 280, 300, 320, 340] self.assertEqual(self.func(data, 20), 265.0) + def test_data_type_error(self): + # Test median_grouped with str, bytes data types for data and interval + data = ["", "", ""] + self.assertRaises(TypeError, self.func, data) + #--- + data = [b"", b"", b""] + self.assertRaises(TypeError, self.func, data) + #--- + data = [1, 2, 3] + interval = "" + self.assertRaises(TypeError, self.func, data, interval) + #--- + data = [1, 2, 3] + interval = b"" + self.assertRaises(TypeError, self.func, data, interval) + class TestMode(NumericTestCase, AverageMixin, UnivariateTypeMixin): # Test cases for the discrete version of mode. |