Description
Code Sample, a copy-pastable example if possible
In [2]: index = pd.date_range('2001-01-01', periods=100)
In [3]: index.get_loc('2001-01')
Out[3]: slice(0, 31, None)
In [4]: index.get_indexer(['2001-01'])
Out[4]: array([-1])
In [5]: s = pd.Series(1, index=index)
In [6]: s.loc['2001-01']
Out[6]:
2001-01-01 1
2001-01-02 1
2001-01-03 1
2001-01-04 1
2001-01-05 1
2001-01-06 1
2001-01-07 1
2001-01-08 1
2001-01-09 1
2001-01-10 1
2001-01-11 1
2001-01-12 1
2001-01-13 1
2001-01-14 1
2001-01-15 1
2001-01-16 1
2001-01-17 1
2001-01-18 1
2001-01-19 1
2001-01-20 1
2001-01-21 1
2001-01-22 1
2001-01-23 1
2001-01-24 1
2001-01-25 1
2001-01-26 1
2001-01-27 1
2001-01-28 1
2001-01-29 1
2001-01-30 1
2001-01-31 1
Freq: D, dtype: int64
In [7]: s.loc[['2001-01']]
---------------------------------------------------------------------------
KeyError Traceback (most recent call last)
<ipython-input-7-f0d6dc35665a> in <module>
----> 1 s.loc[['2001-01']]
/home/nobackup/repo/pandas/pandas/core/indexing.py in __getitem__(self, key)
1427
1428 maybe_callable = com.apply_if_callable(key, self.obj)
-> 1429 return self._getitem_axis(maybe_callable, axis=axis)
1430
1431 def _is_scalar_access(self, key):
/home/nobackup/repo/pandas/pandas/core/indexing.py in _getitem_axis(self, key, axis)
1829 raise ValueError('Cannot index with multidimensional key')
1830
-> 1831 return self._getitem_iterable(key, axis=axis)
1832
1833 # nested tuple slicing
/home/nobackup/repo/pandas/pandas/core/indexing.py in _getitem_iterable(self, key, axis)
1131 # A collection of keys
1132 keyarr, indexer = self._get_listlike_indexer(key, axis,
-> 1133 raise_missing=False)
1134 return self.obj._reindex_with_indexers({axis: [keyarr, indexer]},
1135 copy=True, allow_dups=True)
/home/nobackup/repo/pandas/pandas/core/indexing.py in _get_listlike_indexer(self, key, axis, raise_missing)
1087 self._validate_read_indexer(keyarr, indexer,
1088 o._get_axis_number(axis),
-> 1089 raise_missing=raise_missing)
1090 return keyarr, indexer
1091
/home/nobackup/repo/pandas/pandas/core/indexing.py in _validate_read_indexer(self, key, indexer, axis, raise_missing)
1172 raise KeyError(
1173 "None of [{key}] are in the [{axis}]".format(
-> 1174 key=key, axis=self.obj._get_axis_name(axis)))
1175
1176 # We (temporarily) allow for some missing keys with .loc, except in
KeyError: "None of [Index(['2001-01'], dtype='object')] are in the [index]"
Problem description
If an indexing mechanism works for individual key, it would be expected to also work for lists of keys, and this is more or less the status quo for other indexes that allow some partial/smart selection.
IntervalIndex works just fine:
In [2]: iidx = pd.IntervalIndex.from_breaks([0, 1, 4.6, 7])
In [3]: iidx.get_loc(5)
Out[3]: 2
In [4]: iidx.get_indexer([5])
Out[4]: array([2])
MultiIndex doesn't (will open a bug now)
In [5]: midx = pd.MultiIndex.from_product([[0, 1], [2, 3]])
In [6]: midx.get_loc(0)
Out[6]: slice(0, 2, None)
In [7]: midx.get_indexer([0])
Out[7]: array([-1])
... but this is worked around in indexing code (which shouldn't happen):
In [8]: pd.Series(index=midx).loc[[0]]
Out[8]:
0 2 NaN
3 NaN
dtype: float64
Expected Output
The same as when passing a single key.
Output of pd.show_versions()
INSTALLED VERSIONS
commit : 7ceefb3
python : 3.7.3.candidate.1
python-bits : 64
OS : Linux
OS-release : 4.9.0-9-amd64
machine : x86_64
processor :
byteorder : little
LC_ALL : None
LANG : it_IT.UTF-8
LOCALE : it_IT.UTF-8
pandas : 0.25.0.dev0+861.g7ceefb3f2.dirty
numpy : 1.16.4
pytz : 2016.7
dateutil : 2.8.0
pip : 9.0.1
setuptools : 41.0.1
Cython : 0.29.2
pytest : 4.6.3
hypothesis : 3.71.11
sphinx : 1.4.9
blosc : None
feather : None
xlsxwriter : 0.9.6
lxml.etree : 4.3.2
html5lib : 0.999999999
pymysql : None
psycopg2 : None
jinja2 : 2.10.1
IPython : 7.5.0
pandas_datareader: 0.2.1
bs4 : 4.5.3
bottleneck : 1.2.1
fastparquet : None
gcsfs : None
lxml.etree : 4.3.2
matplotlib : 3.0.2
numexpr : 2.6.9
openpyxl : 2.3.0
pandas_gbq : None
pyarrow : None
pytables : None
s3fs : None
scipy : 1.1.0
sqlalchemy : 1.0.15
tables : 3.4.4
xarray : None
xlrd : 1.0.0
xlwt : 1.3.0
xlsxwriter : 0.9.6