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| author | Stefan Behnel <stefan_ml@behnel.de> | 2019-01-02 13:22:06 +0100 |
|---|---|---|
| committer | Serhiy Storchaka <storchaka@gmail.com> | 2019-01-02 14:22:06 +0200 |
| commit | 3a374e0c5abe805667b71ffaaa7614781101ff4c (patch) | |
| tree | 5b88e9c84d19b725996059a1713d9b1536028980 /Lib/fractions.py | |
| parent | a1d14253066f7dd60cfb465c6511fa565f312b42 (diff) | |
| download | cpython-git-3a374e0c5abe805667b71ffaaa7614781101ff4c.tar.gz | |
bpo-35588: Speed up mod, divmod and floordiv operations for Fraction type (#11322)
* bpo-35588: Implement mod and divmod operations for Fraction type by spelling out the numerator/denominator calculation, instead of instantiating and normalising Fractions along the way. This speeds up '%' and divmod() by 2-3x.
* bpo-35588: Also reimplement Fraction.__floordiv__() using integer operations to make it ~4x faster.
* Improve code formatting.
Co-Authored-By: scoder <stefan_ml@behnel.de>
* bpo-35588: Fix return type of divmod(): the result of the integer division should be an integer.
* bpo-35588: Further specialise __mod__() and inline the original helper function _flat_divmod() since it's no longer reused.
* bpo-35588: Add some tests with large numerators and/or denominators.
* bpo-35588: Use builtin "divmod()" function for implementing __divmod__() in order to simplify the implementation, even though performance results are mixed.
* Rremove accidentally added empty line.
* bpo-35588: Try to provide more informative output on test failures.
* bpo-35588: Improve wording in News entry.
Co-Authored-By: scoder <stefan_ml@behnel.de>
* Remove stray space.
Diffstat (limited to 'Lib/fractions.py')
| -rw-r--r-- | Lib/fractions.py | 14 |
1 files changed, 11 insertions, 3 deletions
diff --git a/Lib/fractions.py b/Lib/fractions.py index e0a024a03b..4bbfc434f7 100644 --- a/Lib/fractions.py +++ b/Lib/fractions.py @@ -429,14 +429,22 @@ class Fraction(numbers.Rational): def _floordiv(a, b): """a // b""" - return math.floor(a / b) + return (a.numerator * b.denominator) // (a.denominator * b.numerator) __floordiv__, __rfloordiv__ = _operator_fallbacks(_floordiv, operator.floordiv) + def _divmod(a, b): + """(a // b, a % b)""" + da, db = a.denominator, b.denominator + div, n_mod = divmod(a.numerator * db, da * b.numerator) + return div, Fraction(n_mod, da * db) + + __divmod__, __rdivmod__ = _operator_fallbacks(_divmod, divmod) + def _mod(a, b): """a % b""" - div = a // b - return a - b * div + da, db = a.denominator, b.denominator + return Fraction((a.numerator * db) % (b.numerator * da), da * db) __mod__, __rmod__ = _operator_fallbacks(_mod, operator.mod) |