BUG: Overflow encountered when using .loc with UInt64Index

[glemaitre]

Code Sample, a copy-pastable example if possible

>>> import pandas as pd
>>> import numpy as np
>>> s = pd.Series([1, 2], index=[np.iinfo('uint64').max - 1, np.iinfo('uint64').max])
>>> s[np.iinfo('uint64').max]
2
>>> s.loc[np.iinfo('uint64').max]

...
OverflowError: Python int too large to convert to C long
During handling of the above exception, another exception occurred:
KeyError
...

>>> s.index
UInt64Index([18446744073709551614, 18446744073709551615], dtype='uint64')

Problem description

loc leads to an overflow even with consistent dtype (uint64 for the index of the Series and the value pass to loc).

Expected Output

>>> s.loc[np.iinfo('uint64').max]
2

Output of pd.show_versions()

INSTALLED VERSIONS
------------------
commit: None
python: 3.6.4.final.0
python-bits: 64
OS: Linux
OS-release: 4.13.0-38-generic
machine: x86_64
processor: x86_64
byteorder: little
LC_ALL: None
LANG: en_US.UTF-8
LOCALE: en_US.UTF-8

pandas: 0.22.0
pytest: 3.3.2
pip: 9.0.1
setuptools: 38.5.1
Cython: 0.27.3
numpy: 1.14.0
scipy: 1.0.0
pyarrow: None
xarray: 0.10.1
IPython: 6.2.1
sphinx: 1.6.6
patsy: 0.5.0
dateutil: 2.6.1
pytz: 2017.3
blosc: None
bottleneck: None
tables: None
numexpr: None
feather: None
matplotlib: 2.1.2
openpyxl: None
xlrd: 1.1.0
xlwt: None
xlsxwriter: None
lxml: None
bs4: 4.6.0
html5lib: 0.9999999
sqlalchemy: None
pymysql: None
psycopg2: None
jinja2: 2.10
s3fs: None
fastparquet: None
pandas_gbq: None
pandas_datareader: None

[jorisvandenbossche]

Thanks for the report!
In contrast to loc, getitem works:

In [29]: s[18446744073709551614]
Out[29]: 1

One of the errors is happening in contains:

In [30]: s.index.contains(18446744073709551614)
---------------------------------------------------------------------------
OverflowError                             Traceback (most recent call last)
<ipython-input-30-cec353dff8b1> in <module>()
----> 1 s.index.contains(18446744073709551614)

/home/joris/scipy/pandas/pandas/core/indexes/base.py in contains(self, key)
   2008         hash(key)
   2009         try:
-> 2010             return key in self._engine
   2011         except (TypeError, ValueError):
   2012             return False

/home/joris/scipy/pandas/pandas/_libs/index.pyx in pandas._libs.index.IndexEngine.__contains__()

/home/joris/scipy/pandas/pandas/_libs/hashtable_class_helper.pxi in pandas._libs.hashtable.UInt64HashTable.__contains__()

OverflowError: Python int too large to convert to C long

cc @gfyoung

[ghost]

Ran into this today. One thing to add is that it seems to only happen when passing a scalar to .loc.

df = pd.DataFrame([[1, 2, 3]], pd.UInt64Index([2**63 + 1]))
df.loc[[df.index[0]]]

works fine but

df.loc[df.index[0]]

raises the error