Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Setting values on non-existing datetime index raises exception only when index has DST changes in range #18308

Closed
dadoeyad opened this issue Nov 15, 2017 · 1 comment

Comments

Projects
None yet
4 participants
@dadoeyad
Copy link

commented Nov 15, 2017

Setting values on datetime index with DST changes

start_date = pd.Timestamp('2017-10-27 00:00:00+0200', tz='Europe/Madrid')
end_date = pd.Timestamp('2017-10-30 00:00:00+0100', tz='Europe/Madrid')

df = pd.DataFrame(index=pd.date_range(start_date, end_date, closed='left', freq="10T"), columns=['value'])

# set value for non existing index (date is 2016), raises exception 
df.loc[pd.Timestamp('2016-10-10 03:00:00', tz='Europe/Madrid'), 'value'] = 12
Exception raised from `df.loc` AmbiguousTimeError Traceback (most recent call last) in () ----> 1 df.loc[pd.Timestamp('2016-10-10 03:00:00', tz='Europe/Madrid'), 'value'] = 12

~/Envs/jupyter/lib/python3.6/site-packages/pandas/core/indexing.py in setitem(self, key, value)
192 key = com._apply_if_callable(key, self.obj)
193 indexer = self._get_setitem_indexer(key)
--> 194 self._setitem_with_indexer(indexer, value)
195
196 def _has_valid_type(self, k, axis):

~/Envs/jupyter/lib/python3.6/site-packages/pandas/core/indexing.py in _setitem_with_indexer(self, indexer, value)
368 # so the object is the same
369 index = self.obj._get_axis(i)
--> 370 labels = index.insert(len(index), key)
371 self.obj._data = self.obj.reindex(labels, axis=i)._data
372 self.obj._maybe_update_cacher(clear=True)

~/Envs/jupyter/lib/python3.6/site-packages/pandas/core/indexes/datetimes.py in insert(self, loc, item)
1734 new_dates = libts.tz_convert(new_dates, 'UTC', self.tz)
1735 return DatetimeIndex(new_dates, name=self.name, freq=freq,
-> 1736 tz=self.tz)
1737
1738 except (AttributeError, TypeError):

~/Envs/jupyter/lib/python3.6/site-packages/pandas/util/_decorators.py in wrapper(*args, **kwargs)
116 else:
117 kwargs[new_arg_name] = new_arg_value
--> 118 return func(*args, **kwargs)
119 return wrapper
120 return _deprecate_kwarg

~/Envs/jupyter/lib/python3.6/site-packages/pandas/core/indexes/datetimes.py in new(cls, data, freq, start, end, periods, copy, name, tz, verify_integrity, normalize, closed, ambiguous, dtype, **kwargs)
388 ints = subarr.view('i8')
389 subarr = libts.tz_localize_to_utc(ints, tz,
--> 390 ambiguous=ambiguous)
391 subarr = subarr.view(_NS_DTYPE)
392

pandas/_libs/tslib.pyx in pandas._libs.tslib.tz_localize_to_utc()

AmbiguousTimeError: Cannot infer dst time from Timestamp('2017-10-29 02:00:00'), try using the 'ambiguous' argument

Setting values on datetime index with no DST changes

start_date = pd.Timestamp('2017-09-27 00:00:00+0200', tz='Europe/Madrid')
end_date = pd.Timestamp('2017-09-30 00:00:00+0100', tz='Europe/Madrid')

df = pd.DataFrame(index=pd.date_range(start_date, end_date, closed='left', freq="10T"), columns=['value'])
df.index

# set value for non existing index creates new row
df.loc[pd.Timestamp('2016-10-10 03:00:00', tz='Europe/Madrid'), 'value'] = 12

Problem description

There seems to be conflicting behaviors when setting values on non-existing index (a datetime that's not already in index) with .loc.

(First code sample) When the datetime index range has DST changes .loc[index, field] = value raises an AmbiguousTimeError.

(Second code sample) When the datetime index range does not have DST changes .loc[index, field] = value creates a new row as normal

Output of pd.show_versions()

[paste the output of pd.show_versions() here below this line]
INSTALLED VERSIONS

commit: None
python: 3.6.3.final.0
python-bits: 64
OS: Darwin
OS-release: 17.2.0
machine: x86_64
processor: i386
byteorder: little
LC_ALL: en_US.UTF-8
LANG: en_US.utf8
LOCALE: en_US.UTF-8

pandas: 0.21.0
pytest: None
pip: 9.0.1
setuptools: 36.7.2
Cython: None
numpy: 1.13.3
scipy: None
pyarrow: None
xarray: None
IPython: 6.2.1
sphinx: None
patsy: None
dateutil: 2.6.1
pytz: 2017.3
blosc: None
bottleneck: None
tables: None
numexpr: None
feather: None
matplotlib: None
openpyxl: None
xlrd: None
xlwt: None
xlsxwriter: None
lxml: None
bs4: None
html5lib: 1.0b10
sqlalchemy: None
pymysql: None
psycopg2: None
jinja2: 2.10
s3fs: None
fastparquet: None
pandas_gbq: None
pandas_datareader: None

@gfyoung gfyoung added the Timezones label Nov 16, 2017

@mroeschke

This comment has been minimized.

Copy link
Member

commented Jul 28, 2018

This looks fixed on master if anyone wants to put up a test:

In [21]: pd.__version__
Out[21]: '0.24.0.dev0+371.g0b7a08b70'

In [22]: start_date = pd.Timestamp('2017-09-27 00:00:00+0200', tz='Europe/Madrid')
    ...: end_date = pd.Timestamp('2017-09-30 00:00:00+0100', tz='Europe/Madrid')
    ...:
    ...: df = pd.DataFrame(index=pd.date_range(start_date, end_date, closed='left', freq="10T"), columns=['value'])
    ...: df.index
    ...:
    ...: # set value for non existing index creates new row
    ...: df.loc[pd.Timestamp('2016-10-10 03:00:00', tz='Europe/Madrid'), 'value'] = 12
    ...:
    ...:

In [23]: df.tail()
Out[23]:
                          value
2017-09-30 00:20:00+02:00   NaN
2017-09-30 00:30:00+02:00   NaN
2017-09-30 00:40:00+02:00   NaN
2017-09-30 00:50:00+02:00   NaN
2016-10-10 03:00:00+02:00    12

@mroeschke mroeschke referenced this issue Aug 5, 2018

Merged

CLN: Old timezone issues #22201

8 of 8 tasks complete

@jreback jreback added this to the 0.24.0 milestone Aug 6, 2018

Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
You can’t perform that action at this time.