BUG: Possible Regression in DatetimeIndex Slicing · Issue #35509 · pandas-dev/pandas (original) (raw)
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Code Sample, a copy-pastable example
import pandas as pd df = pd.DataFrame( ... {'col1': ['a', 'b', 'c'], 'col2': [1, 2, 3]}, ... index=pd.to_datetime(['2020-08-01', '2020-07-02', '2020-08-05']) ... ) df['2020-08']
AssertionError Traceback (most recent call last) in ----> 1 df['2020-08']
~/book_env/lib/python3.7/site-packages/pandas/core/frame.py in getitem(self, key) 2880 # either we have a slice or we have a string that can be converted 2881 # to a slice for partial-string date indexing -> 2882 return self._slice(indexer, axis=0) 2883 2884 # Do we have a (boolean) DataFrame?
~/book_env/lib/python3.7/site-packages/pandas/core/generic.py in _slice(self, slobj, axis) 3546 Slicing with this method is always positional. 3547 """ -> 3548 assert isinstance(slobj, slice), type(slobj) 3549 axis = self._get_block_manager_axis(axis) 3550 result = self._constructor(self._mgr.get_slice(slobj, axis=axis))
AssertionError: <class 'numpy.ndarray'>
You now have to run sort_index() before slicing:
df.sort_index()['2020-08'] col1 col2 2020-08-01 a 1 2020-08-05 c 3
Problem description
Before 1.1.0, you didn't have to sort the index before slicing. Now, you have to run sort_index() and the error message is not helpful at all.
Expected Output
df['2020-08'] col1 col2 2020-08-01 a 1 2020-08-05 c 3
Output of pd.show_versions()
INSTALLED VERSIONS
commit : d9fff27
python : 3.7.3.final.0
python-bits : 64
OS : Linux
OS-release : 5.4.40-04224-g891a6cce2d44
Version : #1 SMP PREEMPT Tue Jun 23 20:21:29 PDT 2020
machine : x86_64
processor :
byteorder : little
LC_ALL : None
LANG : en_US.UTF-8
LOCALE : en_US.UTF-8
pandas : 1.1.0
numpy : 1.19.1
pytz : 2020.1
dateutil : 2.8.1
pip : 18.1
setuptools : 40.8.0
Cython : None
pytest : None
hypothesis : None
sphinx : None
blosc : None
feather : None
xlsxwriter : None
lxml.etree : 4.5.2
html5lib : None
pymysql : None
psycopg2 : None
jinja2 : 2.11.2
IPython : 7.16.1
pandas_datareader: 0.9.0
bs4 : None
bottleneck : None
fsspec : None
fastparquet : None
gcsfs : None
matplotlib : 3.3.0
numexpr : None
odfpy : None
openpyxl : None
pandas_gbq : None
pyarrow : None
pytables : None
pyxlsb : None
s3fs : None
scipy : 1.5.2
sqlalchemy : 1.3.18
tables : None
tabulate : None
xarray : None
xlrd : None
xlwt : None
numba : None