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BUG: guess_datetime_format doesn't guess format correctly for UTC+1 #48954

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Merged
merged 2 commits into from
Oct 5, 2022
Merged

BUG: guess_datetime_format doesn't guess format correctly for UTC+1 #48954

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ef6f086
BUG: guess_datetime_format doesn't guess format correctly for UTC+1
Oct 5, 2022
dee9f33
:doc: add comment on +9 offset
Oct 5, 2022
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10 changes: 9 additions & 1 deletion pandas/_libs/tslibs/parsing.pyx
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Original file line number Diff line number Diff line change
Expand Up @@ -62,6 +62,7 @@ from pandas._libs.tslibs.np_datetime cimport (
string_to_dts,
)
from pandas._libs.tslibs.offsets cimport is_offset_object
from pandas._libs.tslibs.strptime import array_strptime
from pandas._libs.tslibs.util cimport (
get_c_string_buf_and_size,
is_array,
Expand Down Expand Up @@ -958,7 +959,9 @@ def guess_datetime_format(dt_str: str, bint dayfirst=False) -> str | None:

Returns
-------
ret : datetime format string (for `strftime` or `strptime`)
str or None : ret
datetime format string (for `strftime` or `strptime`),
or None if it can't be guessed.
"""

if not isinstance(dt_str, str):
Expand Down Expand Up @@ -1079,6 +1082,11 @@ def guess_datetime_format(dt_str: str, bint dayfirst=False) -> str | None:

guessed_format = ''.join(output_format)

try:
array_strptime(np.asarray([dt_str], dtype=object), guessed_format)
except ValueError:
# Doesn't parse, so this can't be the correct format.
return None
# rebuild string, capturing any inferred padding
dt_str = ''.join(tokens)
if parsed_datetime.strftime(guessed_format) == dt_str:
Expand Down
16 changes: 8 additions & 8 deletions pandas/tests/tslibs/test_parsing.py
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Expand Up @@ -152,25 +152,25 @@ def test_parsers_month_freq(date_str, expected):
("2011-12-30T00:00:00", "%Y-%m-%dT%H:%M:%S"),
("2011-12-30T00:00:00UTC", "%Y-%m-%dT%H:%M:%S%Z"),
("2011-12-30T00:00:00Z", "%Y-%m-%dT%H:%M:%S%z"),
("2011-12-30T00:00:00+9", "%Y-%m-%dT%H:%M:%S%z"),
("2011-12-30T00:00:00+09", "%Y-%m-%dT%H:%M:%S%z"),
("2011-12-30T00:00:00+9", None),
("2011-12-30T00:00:00+09", None),
("2011-12-30T00:00:00+090", None),
("2011-12-30T00:00:00+0900", "%Y-%m-%dT%H:%M:%S%z"),
("2011-12-30T00:00:00-0900", "%Y-%m-%dT%H:%M:%S%z"),
("2011-12-30T00:00:00+09:00", "%Y-%m-%dT%H:%M:%S%z"),
("2011-12-30T00:00:00+09:000", "%Y-%m-%dT%H:%M:%S%z"),
("2011-12-30T00:00:00+9:0", "%Y-%m-%dT%H:%M:%S%z"),
("2011-12-30T00:00:00+09:000", None),
("2011-12-30T00:00:00+9:0", None),
("2011-12-30T00:00:00+09:", None),
("2011-12-30T00:00:00.000000UTC", "%Y-%m-%dT%H:%M:%S.%f%Z"),
("2011-12-30T00:00:00.000000Z", "%Y-%m-%dT%H:%M:%S.%f%z"),
("2011-12-30T00:00:00.000000+9", "%Y-%m-%dT%H:%M:%S.%f%z"),
("2011-12-30T00:00:00.000000+09", "%Y-%m-%dT%H:%M:%S.%f%z"),
("2011-12-30T00:00:00.000000+9", None),
("2011-12-30T00:00:00.000000+09", None),
("2011-12-30T00:00:00.000000+090", None),
("2011-12-30T00:00:00.000000+0900", "%Y-%m-%dT%H:%M:%S.%f%z"),
("2011-12-30T00:00:00.000000-0900", "%Y-%m-%dT%H:%M:%S.%f%z"),
("2011-12-30T00:00:00.000000+09:00", "%Y-%m-%dT%H:%M:%S.%f%z"),
("2011-12-30T00:00:00.000000+09:000", "%Y-%m-%dT%H:%M:%S.%f%z"),
("2011-12-30T00:00:00.000000+9:0", "%Y-%m-%dT%H:%M:%S.%f%z"),
("2011-12-30T00:00:00.000000+09:000", None),
("2011-12-30T00:00:00.000000+9:0", None),
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Could you add a comment in the test to note that odd +9 format shouldn't be supported by %z but dateutil.parse can support this format?

("2011-12-30T00:00:00.000000+09:", None),
("2011-12-30 00:00:00.000000", "%Y-%m-%d %H:%M:%S.%f"),
("Tue 24 Aug 2021 01:30:48 AM", "%a %d %b %Y %H:%M:%S %p"),
Expand Down