BUG: pd.core.algorithms.duplicated fails with masked Series

[tehunter]

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

>>> import pandas as pd
>>> data = pd.Series([0, 1, pd.NA, 1], dtype=pd.Int64Dtype())
>>> pd.core.algorithms.duplicated(data)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/pandas/pandas/core/algorithms.py", line 1061, in duplicated
    return htable.duplicated(values._data, keep=keep, mask=values._mask)
  File "/home/pandas/pandas/core/generic.py", line 5941, in __getattr__
    return object.__getattribute__(self, name)
AttributeError: 'Series' object has no attribute '_mask'
>>>

Issue Description

On the main branch, when #48150 was implemented to support a masked ExtensionArray in the duplicated algorithm, it broke the function when a masked Series is passed. I believe values should be cast to values._values in the case of a Series.

Expected Behavior

duplicated succeeds for values of nd.array, ExtensionArray or Series type.

Installed Versions

INSTALLED VERSIONS

commit : 6b93a0c
python : 3.8.13.final.0
python-bits : 64
OS : Linux
OS-release :
Version : #1 SMP Wed Mar 2 00:30:59 UTC 2022
machine : x86_64
processor : x86_64
byteorder : little
LC_ALL : C.UTF-8
LANG : C.UTF-8
LOCALE : en_US.UTF-8

pandas : 1.6.0.dev0+202.g6b93a0c668.dirty
numpy : 1.22.4
pytz : 2022.2.1
dateutil : 2.8.2
setuptools : 65.3.0
pip : 22.2.2
Cython : 0.29.32
pytest : 7.1.3
hypothesis : 6.54.6
sphinx : 4.5.0
blosc : None
feather : None
xlsxwriter : 3.0.3
lxml.etree : 4.9.1
html5lib : 1.1
pymysql : 1.0.2
psycopg2 : 2.9.3
jinja2 : 3.0.3
IPython : 8.5.0
pandas_datareader: 0.10.0
bs4 : 4.11.1
bottleneck : 1.3.5
brotli :
fastparquet : 0.8.3
fsspec : 2021.11.0
gcsfs : 2021.11.0
matplotlib : 3.6.0
numba : 0.55.2
numexpr : 2.8.3
odfpy : None
openpyxl : 3.0.10
pandas_gbq : 0.17.8
pyarrow : 9.0.0
pyreadstat : 1.1.9
pyxlsb : 1.0.9
s3fs : 2021.11.0
scipy : 1.9.1
snappy :
sqlalchemy : 1.4.41
tables : 3.7.0
tabulate : 0.8.10
xarray : 2022.6.0
xlrd : 2.0.1
xlwt : 1.3.0
zstandard : 0.18.0
tzdata : None

[phofl]

This is not supported according to the type hints there. A bit unfortunate that it is mentioned in the docstring, but I am not aware of a place where we call this as a Series.

[tehunter]

Thanks! I should have dug deeper into the type definition.