diff options
| -rw-r--r-- | Include/pytime.h | 4 | ||||
| -rw-r--r-- | Lib/datetime.py | 12 | ||||
| -rw-r--r-- | Lib/test/datetimetester.py | 14 | ||||
| -rw-r--r-- | Misc/NEWS | 5 | ||||
| -rw-r--r-- | Modules/_datetimemodule.c | 22 | ||||
| -rw-r--r-- | Python/pytime.c | 3 |
6 files changed, 26 insertions, 34 deletions
diff --git a/Include/pytime.h b/Include/pytime.h index 98ae12b..41fb806 100644 --- a/Include/pytime.h +++ b/Include/pytime.h @@ -44,6 +44,10 @@ PyAPI_FUNC(PyObject *) _PyLong_FromTime_t( PyAPI_FUNC(time_t) _PyLong_AsTime_t( PyObject *obj); +/* Round to nearest with ties going away from zero (_PyTime_ROUND_HALF_UP). */ +PyAPI_FUNC(double) _PyTime_RoundHalfUp( + double x); + /* Convert a number of seconds, int or float, to time_t. */ PyAPI_FUNC(int) _PyTime_ObjectToTime_t( PyObject *obj, diff --git a/Lib/datetime.py b/Lib/datetime.py index db13b12..d661460 100644 --- a/Lib/datetime.py +++ b/Lib/datetime.py @@ -316,6 +316,14 @@ def _divide_and_round(a, b): return q +def _round_half_up(x): + """Round to nearest with ties going away from zero.""" + if x >= 0.0: + return _math.floor(x + 0.5) + else: + return _math.ceil(x - 0.5) + + class timedelta: """Represent the difference between two datetime objects. @@ -399,7 +407,7 @@ class timedelta: # secondsfrac isn't referenced again if isinstance(microseconds, float): - microseconds = round(microseconds + usdouble) + microseconds = _round_half_up(microseconds + usdouble) seconds, microseconds = divmod(microseconds, 1000000) days, seconds = divmod(seconds, 24*3600) d += days @@ -410,7 +418,7 @@ class timedelta: days, seconds = divmod(seconds, 24*3600) d += days s += seconds - microseconds = round(microseconds + usdouble) + microseconds = _round_half_up(microseconds + usdouble) assert isinstance(s, int) assert isinstance(microseconds, int) assert abs(s) <= 3 * 24 * 3600 diff --git a/Lib/test/datetimetester.py b/Lib/test/datetimetester.py index babeb44..62f5527 100644 --- a/Lib/test/datetimetester.py +++ b/Lib/test/datetimetester.py @@ -662,28 +662,24 @@ class TestTimeDelta(HarmlessMixedComparison, unittest.TestCase): # Single-field rounding. eq(td(milliseconds=0.4/1000), td(0)) # rounds to 0 eq(td(milliseconds=-0.4/1000), td(0)) # rounds to 0 - eq(td(milliseconds=0.5/1000), td(microseconds=0)) - eq(td(milliseconds=-0.5/1000), td(microseconds=0)) + eq(td(milliseconds=0.5/1000), td(microseconds=1)) + eq(td(milliseconds=-0.5/1000), td(microseconds=-1)) eq(td(milliseconds=0.6/1000), td(microseconds=1)) eq(td(milliseconds=-0.6/1000), td(microseconds=-1)) - eq(td(seconds=0.5/10**6), td(microseconds=0)) - eq(td(seconds=-0.5/10**6), td(microseconds=0)) + eq(td(seconds=0.5/10**6), td(microseconds=1)) + eq(td(seconds=-0.5/10**6), td(microseconds=-1)) # Rounding due to contributions from more than one field. us_per_hour = 3600e6 us_per_day = us_per_hour * 24 eq(td(days=.4/us_per_day), td(0)) eq(td(hours=.2/us_per_hour), td(0)) - eq(td(days=.4/us_per_day, hours=.2/us_per_hour), td(microseconds=1)) + eq(td(days=.4/us_per_day, hours=.2/us_per_hour), td(microseconds=1), td) eq(td(days=-.4/us_per_day), td(0)) eq(td(hours=-.2/us_per_hour), td(0)) eq(td(days=-.4/us_per_day, hours=-.2/us_per_hour), td(microseconds=-1)) - # Test for a patch in Issue 8860 - eq(td(microseconds=0.5), 0.5*td(microseconds=1.0)) - eq(td(microseconds=0.5)//td.resolution, 0.5*td.resolution//td.resolution) - def test_massive_normalization(self): td = timedelta(microseconds=-1) self.assertEqual((td.days, td.seconds, td.microseconds), @@ -17,6 +17,11 @@ Core and Builtins Library ------- +- Issue #23517: datetime.timedelta constructor now rounds microseconds to + nearest with ties going away from zero (ROUND_HALF_UP), as Python 2 and + Python older than 3.3, instead of rounding to nearest with ties going to + nearest even integer (ROUND_HALF_EVEN). + - Issue #23552: Timeit now warns when there is substantial (4x) variance between best and worst times. Patch from Serhiy Storchaka. diff --git a/Modules/_datetimemodule.c b/Modules/_datetimemodule.c index 5cff3f8..6cab1e2 100644 --- a/Modules/_datetimemodule.c +++ b/Modules/_datetimemodule.c @@ -2149,29 +2149,9 @@ delta_new(PyTypeObject *type, PyObject *args, PyObject *kw) if (leftover_us) { /* Round to nearest whole # of us, and add into x. */ double whole_us = round(leftover_us); - int x_is_odd; PyObject *temp; - whole_us = round(leftover_us); - if (fabs(whole_us - leftover_us) == 0.5) { - /* We're exactly halfway between two integers. In order - * to do round-half-to-even, we must determine whether x - * is odd. Note that x is odd when it's last bit is 1. The - * code below uses bitwise and operation to check the last - * bit. */ - temp = PyNumber_And(x, one); /* temp <- x & 1 */ - if (temp == NULL) { - Py_DECREF(x); - goto Done; - } - x_is_odd = PyObject_IsTrue(temp); - Py_DECREF(temp); - if (x_is_odd == -1) { - Py_DECREF(x); - goto Done; - } - whole_us = 2.0 * round((leftover_us + x_is_odd) * 0.5) - x_is_odd; - } + whole_us = _PyTime_RoundHalfUp(leftover_us); temp = PyLong_FromLong((long)whole_us); diff --git a/Python/pytime.c b/Python/pytime.c index ffb390a..02a1edf 100644 --- a/Python/pytime.c +++ b/Python/pytime.c @@ -60,8 +60,7 @@ _PyLong_FromTime_t(time_t t) #endif } -/* Round to nearest with ties going away from zero (_PyTime_ROUND_HALF_UP). */ -static double +double _PyTime_RoundHalfUp(double x) { /* volatile avoids optimization changing how numbers are rounded */ |