Merge pull request #665 from anthrotype/py23-round
[py23] add round2 and round3 functions
This commit is contained in:
Cosimo Lupo
GitHub
commit
88f7b06ce5
@ -6,13 +6,17 @@ import sys
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__all__ = ['basestring', 'unicode', 'unichr', 'byteord', 'bytechr', 'BytesIO',
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'StringIO', 'UnicodeIO', 'strjoin', 'bytesjoin', 'tobytes', 'tostr',
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'tounicode', 'Tag', 'open', 'range', 'xrange', 'Py23Error']
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'tounicode', 'Tag', 'open', 'range', 'xrange', 'round', 'Py23Error']
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class Py23Error(NotImplementedError):
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pass
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PY3 = sys.version_info[0] == 3
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PY2 = sys.version_info[0] == 2
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try:
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basestring = basestring
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except NameError:
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@ -255,6 +259,94 @@ def xrange(*args, **kwargs):
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raise Py23Error("'xrange' is not defined. Use 'range' instead.")
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import decimal as _decimal
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def round2(number, ndigits=None):
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"""
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See Python 2 documentation.
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Rounds a number to a given precision in decimal digits (default
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0 digits). The result is a floating point number. Values are rounded
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to the closest multiple of 10 to the power minus ndigits; if two
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multiples are equally close, rounding is done away from 0.
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ndigits may be negative.
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"""
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if ndigits is None:
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ndigits = 0
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elif hasattr(ndigits, '__index__'):
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# any type with an __index__ method should be permitted as
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# a second argument
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ndigits = ndigits.__index__()
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if ndigits < 0:
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exponent = 10 ** (-ndigits)
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quotient, remainder = divmod(number, exponent)
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if remainder >= exponent//2 and number >= 0:
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quotient += 1
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return float(quotient * exponent)
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else:
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exponent = _decimal.Decimal('10') ** (-ndigits)
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d = _decimal.Decimal.from_float(number).quantize(
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exponent, rounding=_decimal.ROUND_HALF_UP)
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return float(d)
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def round3(number, ndigits=None):
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"""
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See Python 3 documentation: uses Banker's Rounding.
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Delegates to the __round__ method if for some reason this exists.
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If not, rounds a number to a given precision in decimal digits (default
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0 digits). This returns an int when called with one argument,
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otherwise the same type as the number. ndigits may be negative.
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ndigits may be negative.
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Derived from python-future:
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https://github.com/PythonCharmers/python-future/blob/master/src/future/builtins/newround.py
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"""
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return_int = False
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if ndigits is None:
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return_int = True
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ndigits = 0
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if hasattr(number, '__round__'):
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d = number.__round__(ndigits)
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return int(d) if return_int else float(d)
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if hasattr(ndigits, '__index__'):
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# any type with an __index__ method should be permitted as
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# a second argument
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ndigits = ndigits.__index__()
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if ndigits < 0:
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exponent = 10 ** (-ndigits)
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quotient, remainder = divmod(number, exponent)
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half = exponent//2
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if remainder > half or (remainder == half and quotient % 2 != 0):
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quotient += 1
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d = quotient * exponent
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else:
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exponent = _decimal.Decimal('10') ** (-ndigits)
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d = _decimal.Decimal.from_float(number).quantize(
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exponent, rounding=_decimal.ROUND_HALF_EVEN)
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return int(d) if return_int else float(d)
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if PY2:
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round = round3
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else:
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import builtins
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round = builtins.round
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import logging
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@ -8,6 +8,8 @@ import sys
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import os
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import unittest
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from fontTools.misc.py23 import round2, round3
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PIPE_SCRIPT = """\
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import sys
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@ -65,5 +67,188 @@ class OpenFuncWrapperTest(unittest.TestCase):
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self.assertEqual(result, expected)
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class Round2Test(unittest.TestCase):
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"""
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Test cases taken from cpython 2.7 test suite:
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https://github.com/python/cpython/blob/2.7/Lib/test/test_float.py#L748
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Excludes the test cases that are not supported when using the `decimal`
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module's `quantize` method.
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"""
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def test_second_argument_type(self):
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# any type with an __index__ method should be permitted as
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# a second argument
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self.assertAlmostEqual(round2(12.34, True), 12.3)
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class MyIndex(object):
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def __index__(self): return 4
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self.assertAlmostEqual(round2(-0.123456, MyIndex()), -0.1235)
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# but floats should be illegal
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self.assertRaises(TypeError, round2, 3.14159, 2.0)
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def test_halfway_cases(self):
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# Halfway cases need special attention, since the current
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# implementation has to deal with them specially. Note that
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# 2.x rounds halfway values up (i.e., away from zero) while
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# 3.x does round-half-to-even.
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self.assertAlmostEqual(round2(0.125, 2), 0.13)
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self.assertAlmostEqual(round2(0.375, 2), 0.38)
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self.assertAlmostEqual(round2(0.625, 2), 0.63)
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self.assertAlmostEqual(round2(0.875, 2), 0.88)
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self.assertAlmostEqual(round2(-0.125, 2), -0.13)
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self.assertAlmostEqual(round2(-0.375, 2), -0.38)
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self.assertAlmostEqual(round2(-0.625, 2), -0.63)
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self.assertAlmostEqual(round2(-0.875, 2), -0.88)
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self.assertAlmostEqual(round2(0.25, 1), 0.3)
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self.assertAlmostEqual(round2(0.75, 1), 0.8)
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self.assertAlmostEqual(round2(-0.25, 1), -0.3)
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self.assertAlmostEqual(round2(-0.75, 1), -0.8)
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self.assertEqual(round2(-6.5, 0), -7.0)
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self.assertEqual(round2(-5.5, 0), -6.0)
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self.assertEqual(round2(-1.5, 0), -2.0)
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self.assertEqual(round2(-0.5, 0), -1.0)
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self.assertEqual(round2(0.5, 0), 1.0)
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self.assertEqual(round2(1.5, 0), 2.0)
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self.assertEqual(round2(2.5, 0), 3.0)
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self.assertEqual(round2(3.5, 0), 4.0)
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self.assertEqual(round2(4.5, 0), 5.0)
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self.assertEqual(round2(5.5, 0), 6.0)
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self.assertEqual(round2(6.5, 0), 7.0)
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# same but without an explicit second argument; in 3.x these
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# will give integers
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self.assertEqual(round2(-6.5), -7.0)
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self.assertEqual(round2(-5.5), -6.0)
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self.assertEqual(round2(-1.5), -2.0)
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self.assertEqual(round2(-0.5), -1.0)
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self.assertEqual(round2(0.5), 1.0)
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self.assertEqual(round2(1.5), 2.0)
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self.assertEqual(round2(2.5), 3.0)
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self.assertEqual(round2(3.5), 4.0)
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self.assertEqual(round2(4.5), 5.0)
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self.assertEqual(round2(5.5), 6.0)
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self.assertEqual(round2(6.5), 7.0)
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self.assertEqual(round2(-25.0, -1), -30.0)
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self.assertEqual(round2(-15.0, -1), -20.0)
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self.assertEqual(round2(-5.0, -1), -10.0)
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self.assertEqual(round2(5.0, -1), 10.0)
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self.assertEqual(round2(15.0, -1), 20.0)
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self.assertEqual(round2(25.0, -1), 30.0)
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self.assertEqual(round2(35.0, -1), 40.0)
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self.assertEqual(round2(45.0, -1), 50.0)
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self.assertEqual(round2(55.0, -1), 60.0)
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self.assertEqual(round2(65.0, -1), 70.0)
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self.assertEqual(round2(75.0, -1), 80.0)
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self.assertEqual(round2(85.0, -1), 90.0)
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self.assertEqual(round2(95.0, -1), 100.0)
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self.assertEqual(round2(12325.0, -1), 12330.0)
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self.assertEqual(round2(0, -1), 0.0)
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self.assertEqual(round2(350.0, -2), 400.0)
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self.assertEqual(round2(450.0, -2), 500.0)
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self.assertAlmostEqual(round2(0.5e21, -21), 1e21)
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self.assertAlmostEqual(round2(1.5e21, -21), 2e21)
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self.assertAlmostEqual(round2(2.5e21, -21), 3e21)
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self.assertAlmostEqual(round2(5.5e21, -21), 6e21)
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self.assertAlmostEqual(round2(8.5e21, -21), 9e21)
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self.assertAlmostEqual(round2(-1.5e22, -22), -2e22)
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self.assertAlmostEqual(round2(-0.5e22, -22), -1e22)
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self.assertAlmostEqual(round2(0.5e22, -22), 1e22)
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self.assertAlmostEqual(round2(1.5e22, -22), 2e22)
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class Round3Test(unittest.TestCase):
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""" Same as above but results adapted for Python 3 round() """
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def test_second_argument_type(self):
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# any type with an __index__ method should be permitted as
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# a second argument
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self.assertAlmostEqual(round3(12.34, True), 12.3)
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class MyIndex(object):
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def __index__(self): return 4
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self.assertAlmostEqual(round3(-0.123456, MyIndex()), -0.1235)
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# but floats should be illegal
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self.assertRaises(TypeError, round3, 3.14159, 2.0)
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def test_halfway_cases(self):
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self.assertAlmostEqual(round3(0.125, 2), 0.12)
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self.assertAlmostEqual(round3(0.375, 2), 0.38)
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self.assertAlmostEqual(round3(0.625, 2), 0.62)
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self.assertAlmostEqual(round3(0.875, 2), 0.88)
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self.assertAlmostEqual(round3(-0.125, 2), -0.12)
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self.assertAlmostEqual(round3(-0.375, 2), -0.38)
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self.assertAlmostEqual(round3(-0.625, 2), -0.62)
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self.assertAlmostEqual(round3(-0.875, 2), -0.88)
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self.assertAlmostEqual(round3(0.25, 1), 0.2)
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self.assertAlmostEqual(round3(0.75, 1), 0.8)
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self.assertAlmostEqual(round3(-0.25, 1), -0.2)
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self.assertAlmostEqual(round3(-0.75, 1), -0.8)
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self.assertEqual(round3(-6.5, 0), -6.0)
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self.assertEqual(round3(-5.5, 0), -6.0)
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self.assertEqual(round3(-1.5, 0), -2.0)
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self.assertEqual(round3(-0.5, 0), 0.0)
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self.assertEqual(round3(0.5, 0), 0.0)
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self.assertEqual(round3(1.5, 0), 2.0)
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self.assertEqual(round3(2.5, 0), 2.0)
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self.assertEqual(round3(3.5, 0), 4.0)
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self.assertEqual(round3(4.5, 0), 4.0)
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self.assertEqual(round3(5.5, 0), 6.0)
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self.assertEqual(round3(6.5, 0), 6.0)
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# same but without an explicit second argument; in 2.x these
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# will give floats
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self.assertEqual(round3(-6.5), -6)
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self.assertEqual(round3(-5.5), -6)
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self.assertEqual(round3(-1.5), -2.0)
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self.assertEqual(round3(-0.5), 0)
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self.assertEqual(round3(0.5), 0)
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self.assertEqual(round3(1.5), 2)
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self.assertEqual(round3(2.5), 2)
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self.assertEqual(round3(3.5), 4)
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self.assertEqual(round3(4.5), 4)
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self.assertEqual(round3(5.5), 6)
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self.assertEqual(round3(6.5), 6)
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self.assertEqual(round3(-25.0, -1), -20.0)
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self.assertEqual(round3(-15.0, -1), -20.0)
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self.assertEqual(round3(-5.0, -1), 0.0)
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self.assertEqual(round3(5.0, -1), 0.0)
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self.assertEqual(round3(15.0, -1), 20.0)
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self.assertEqual(round3(25.0, -1), 20.0)
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self.assertEqual(round3(35.0, -1), 40.0)
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self.assertEqual(round3(45.0, -1), 40.0)
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self.assertEqual(round3(55.0, -1), 60.0)
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self.assertEqual(round3(65.0, -1), 60.0)
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self.assertEqual(round3(75.0, -1), 80.0)
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self.assertEqual(round3(85.0, -1), 80.0)
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self.assertEqual(round3(95.0, -1), 100.0)
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self.assertEqual(round3(12325.0, -1), 12320.0)
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self.assertEqual(round3(0, -1), 0.0)
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self.assertEqual(round3(350.0, -2), 400.0)
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self.assertEqual(round3(450.0, -2), 400.0)
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self.assertAlmostEqual(round3(0.5e21, -21), 0.0)
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self.assertAlmostEqual(round3(1.5e21, -21), 2e21)
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self.assertAlmostEqual(round3(2.5e21, -21), 2e21)
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self.assertAlmostEqual(round3(5.5e21, -21), 6e21)
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self.assertAlmostEqual(round3(8.5e21, -21), 8e21)
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self.assertAlmostEqual(round3(-1.5e22, -22), -2e22)
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self.assertAlmostEqual(round3(-0.5e22, -22), 0.0)
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self.assertAlmostEqual(round3(0.5e22, -22), 0.0)
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self.assertAlmostEqual(round3(1.5e22, -22), 2e22)
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if __name__ == "__main__":
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unittest.main()
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