BUG: Series.str.get with arrow String Dtype allows index to be floating point value

[wirable23]

Pandas version checks

• I have checked that this issue has not already been reported.

• I have confirmed this bug exists on the latest version of pandas.

• I have confirmed this bug exists on the main branch of pandas.

Reproducible Example

>>> a = pd.Series(["ab"], dtype=pd.ArrowDtype(pa.string()))
>>> a.str.get(1.2)
0    b
dtype: string[pyarrow]
>>>

Issue Description

According to the documentation, the index is required to be an int, so this should fail. When using the pandas StringDtype() an error is raised.

Expected Behavior

>>> a2 = pd.Series(["ab"], dtype=pd.StringDtype())
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "C:\pd_201_0425\lib\site-packages\pandas\core\strings\accessor.py", line 1059, in get
    result = self._data.array._str_get(i)
  File "C:\pd_201_0425\lib\site-packages\pandas\core\strings\object_array.py", line 269, in _str_get
    return self._str_map(f)
  File "C:\pd_201_0425\lib\site-packages\pandas\core\arrays\string_.py", line 599, in _str_map
    result = lib.map_infer_mask(
  File "pandas\_libs\lib.pyx", line 2786, in pandas._libs.lib.map_infer_mask
  File "C:\pd_201_0425\lib\site-packages\pandas\core\strings\object_array.py", line 266, in f
    return x[i]
TypeError: string indices must be integers
>>>

I expect an error to be raised, as the method is documented to require an integral index.

Installed Versions

INSTALLED VERSIONS

commit : 37ea63d
python : 3.8.10.final.0
python-bits : 64
OS : Windows
OS-release : 10
Version : 10.0.22621
machine : AMD64
processor : Intel64 Family 6 Model 85 Stepping 7, GenuineIntel
byteorder : little
LC_ALL : None
LANG : None
LOCALE : English_United States.1252

pandas : 2.0.1
numpy : 1.24.3
pytz : 2023.3
dateutil : 2.8.2
setuptools : 67.6.1
pip : 23.0.1
Cython : None
pytest : 7.0.1
hypothesis : None
sphinx : 4.2.0
blosc : None
feather : None
xlsxwriter : None
lxml.etree : None
html5lib : None
pymysql : None
psycopg2 : None
jinja2 : 3.1.2
IPython : 8.12.0
pandas_datareader: None
bs4 : 4.12.2
bottleneck : None
brotli : None
fastparquet : None
fsspec : None
gcsfs : None
matplotlib : None
numba : None
numexpr : None
odfpy : None
openpyxl : None
pandas_gbq : None
pyarrow : 11.0.0
pyreadstat : None
pyxlsb : None
s3fs : None
scipy : None
snappy : None
sqlalchemy : None
tables : None
tabulate : 0.8.9
xarray : None
xlrd : None
zstandard : None
tzdata : 2023.3
qtpy : None
pyqt5 : None

[mroeschke]

Thanks for the report. I suppose we could raise an error in pandas but this appears to also happen in pyarrow: apache/arrow#35385

[mroeschke]

Closing as an upstream bug in apache/arrow#35385