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