104 lines
4.0 KiB
Python
104 lines
4.0 KiB
Python
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"""
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Test the scalar constructors, which also do type-coercion
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"""
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import fractions
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import platform
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import pytest
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import numpy as np
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from numpy.testing import assert_equal, assert_raises
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class TestAsIntegerRatio:
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# derived in part from the cpython test "test_floatasratio"
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@pytest.mark.parametrize("ftype", [
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np.half, np.single, np.double, np.longdouble])
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@pytest.mark.parametrize("f, ratio", [
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(0.875, (7, 8)),
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(-0.875, (-7, 8)),
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(0.0, (0, 1)),
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(11.5, (23, 2)),
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])
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def test_small(self, ftype, f, ratio):
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assert_equal(ftype(f).as_integer_ratio(), ratio)
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@pytest.mark.parametrize("ftype", [
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np.half, np.single, np.double, np.longdouble])
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def test_simple_fractions(self, ftype):
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R = fractions.Fraction
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assert_equal(R(0, 1),
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R(*ftype(0.0).as_integer_ratio()))
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assert_equal(R(5, 2),
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R(*ftype(2.5).as_integer_ratio()))
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assert_equal(R(1, 2),
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R(*ftype(0.5).as_integer_ratio()))
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assert_equal(R(-2100, 1),
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R(*ftype(-2100.0).as_integer_ratio()))
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@pytest.mark.parametrize("ftype", [
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np.half, np.single, np.double, np.longdouble])
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def test_errors(self, ftype):
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assert_raises(OverflowError, ftype('inf').as_integer_ratio)
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assert_raises(OverflowError, ftype('-inf').as_integer_ratio)
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assert_raises(ValueError, ftype('nan').as_integer_ratio)
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def test_against_known_values(self):
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R = fractions.Fraction
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assert_equal(R(1075, 512),
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R(*np.half(2.1).as_integer_ratio()))
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assert_equal(R(-1075, 512),
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R(*np.half(-2.1).as_integer_ratio()))
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assert_equal(R(4404019, 2097152),
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R(*np.single(2.1).as_integer_ratio()))
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assert_equal(R(-4404019, 2097152),
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R(*np.single(-2.1).as_integer_ratio()))
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assert_equal(R(4728779608739021, 2251799813685248),
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R(*np.double(2.1).as_integer_ratio()))
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assert_equal(R(-4728779608739021, 2251799813685248),
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R(*np.double(-2.1).as_integer_ratio()))
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# longdouble is platform dependent
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@pytest.mark.parametrize("ftype, frac_vals, exp_vals", [
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# dtype test cases generated using hypothesis
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# first five generated cases per dtype
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(np.half, [0.0, 0.01154830649280303, 0.31082276347447274,
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0.527350517124794, 0.8308562335072596],
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[0, 1, 0, -8, 12]),
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(np.single, [0.0, 0.09248576989263226, 0.8160498218131407,
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0.17389442853722373, 0.7956044195067877],
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[0, 12, 10, 17, -26]),
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(np.double, [0.0, 0.031066908499895136, 0.5214135908877832,
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0.45780736035689296, 0.5906586745934036],
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[0, -801, 51, 194, -653]),
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pytest.param(
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np.longdouble,
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[0.0, 0.20492557202724854, 0.4277180662199366, 0.9888085019891495,
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0.9620175814461964],
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[0, -7400, 14266, -7822, -8721],
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marks=[
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pytest.mark.skipif(
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np.finfo(np.double) == np.finfo(np.longdouble),
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reason="long double is same as double"),
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pytest.mark.skipif(
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platform.machine().startswith("ppc"),
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reason="IBM double double"),
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]
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)
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])
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def test_roundtrip(self, ftype, frac_vals, exp_vals):
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for frac, exp in zip(frac_vals, exp_vals):
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f = np.ldexp(frac, exp, dtype=ftype)
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n, d = f.as_integer_ratio()
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try:
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# workaround for gh-9968
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nf = np.longdouble(str(n))
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df = np.longdouble(str(d))
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except (OverflowError, RuntimeWarning):
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# the values may not fit in any float type
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pytest.skip("longdouble too small on this platform")
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assert_equal(nf / df, f, "{}/{}".format(n, d))
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