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BUG: Timestamp retains frequency of input Timestamps #23503

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Merged
merged 7 commits into from
Nov 7, 2018
Merged

BUG: Timestamp retains frequency of input Timestamps #23503

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232c29b
BUG: Timestamp retains frequency of input Timestamps
Nov 5, 2018
4f34c01
Be a little more strict with offset checking
Nov 5, 2018
a14776e
Merge remote-tracking branch 'upstream/master' into timestamp_roundtr…
Nov 5, 2018
41fcdd7
use better offest check
Nov 5, 2018
5854b88
Merge remote-tracking branch 'upstream/master' into timestamp_roundtr…
Nov 6, 2018
2dcb1fb
Merge remote-tracking branch 'upstream/master' into timestamp_roundtr…
Nov 7, 2018
218e418
Merge remote-tracking branch 'upstream/master' into timestamp_roundtr…
Nov 7, 2018
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1 change: 1 addition & 0 deletions doc/source/whatsnew/v0.24.0.txt
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Expand Up @@ -1121,6 +1121,7 @@ Datetimelike
- Bug in :func:`date_range` with frequency of ``Day`` or higher where dates sufficiently far in the future could wrap around to the past instead of raising ``OutOfBoundsDatetime`` (:issue:`14187`)
- Bug in :class:`PeriodIndex` with attribute ``freq.n`` greater than 1 where adding a :class:`DateOffset` object would return incorrect results (:issue:`23215`)
- Bug in :class:`Series` that interpreted string indices as lists of characters when setting datetimelike values (:issue:`23451`)
- Bug in :class:`Timestamp` constructor which would drop the frequency of an input :class:`Timestamp` (:issue:`22311`)

Timedelta
^^^^^^^^^
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6 changes: 5 additions & 1 deletion pandas/_libs/tslibs/timestamps.pyx
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Expand Up @@ -16,7 +16,8 @@ from cpython.datetime cimport (datetime,
PyDateTime_IMPORT

from util cimport (is_datetime64_object, is_timedelta64_object,
is_integer_object, is_string_object, is_array)
is_integer_object, is_string_object, is_array,
is_offset_object)

cimport ccalendar
from conversion import tz_localize_to_utc, normalize_i8_timestamps
Expand Down Expand Up @@ -734,6 +735,9 @@ class Timestamp(_Timestamp):

if is_string_object(freq):
freq = to_offset(freq)
elif not is_offset_object(freq):
# GH 22311: Try to extract the frequency of a given Timestamp input
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What do we expect it to be in this case? Aside from None I guess

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This can be a Timestamp in which we want to extract its frequency and pass along.

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IIUC you're referring to ts_input being a Timestamp. I'm asking what freq is in this case. More specifically, anything other than None seems like it should be invalid. Or am I missing something?

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Ah sorry for misunderstanding. You're correct in that this is essentially swallowing any nonsense frequency and just returning None

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freq should only ever be None, a offset string, or offset object

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Won't this silently pass if freq has invalid type? Couldn't we just say that freq = getattr(ts_input, 'freq', None) if freq is None else freq?

freq = getattr(ts_input, 'freq', None)

return create_timestamp_from_ts(ts.value, ts.dts, ts.tzinfo, freq)

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6 changes: 6 additions & 0 deletions pandas/tests/scalar/timestamp/test_timestamp.py
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Expand Up @@ -569,6 +569,12 @@ def test_construct_with_different_string_format(self, arg):
expected = Timestamp(datetime(2013, 1, 1), tz=pytz.FixedOffset(540))
assert result == expected

def test_construct_timestamp_preserve_original_frequency(self):
# GH 22311
result = Timestamp(Timestamp('2010-08-08', freq='D')).freq
expected = offsets.Day()
assert result == expected


class TestTimestamp(object):

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