BUG: duplicated() raises error with singlton set as subset

[camold]

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
df = pd.DataFrame([{"a": "foo", "b": "bar"}])
df.duplicated(subset={"a"}) # raises error
df.duplicated(subset=["a"]) # works
df.duplicated(subset=("a",)) # works
df.duplicates(subset={"a","b"}) # works

Issue Description

Providing a singleton set to the subset parameter raises an error.

Expected Behavior

Should work normally without having to convert the input to list or tuple.

Installed Versions

INSTALLED VERSIONS

commit : 0691c5c
python : 3.12.3
python-bits : 64
OS : Linux
OS-release : 6.11.0-26-generic
Version : #26~24.04.1-Ubuntu SMP PREEMPT_DYNAMIC Thu Apr 17 19:20:47 UTC 2
machine : x86_64
processor : x86_64
byteorder : little
LC_ALL : None
LANG : de_DE.UTF-8
LOCALE : de_DE.UTF-8

pandas : 2.2.3
numpy : 2.2.0
pytz : 2024.2
dateutil : 2.9.0.post0
pip : 24.0
Cython : None
sphinx : None
IPython : 8.29.0
adbc-driver-postgresql: None
adbc-driver-sqlite : None
bs4 : 4.12.3
blosc : None
bottleneck : None
dataframe-api-compat : None
fastparquet : None
fsspec : None
html5lib : None
hypothesis : None
gcsfs : None
jinja2 : 3.1.4
lxml.etree : 5.3.0
matplotlib : 3.9.2
numba : None
numexpr : None
odfpy : None
openpyxl : 3.1.5
pandas_gbq : None
psycopg2 : None
pymysql : None
pyarrow : None
pyreadstat : None
pytest : 8.3.3
python-calamine : None
pyxlsb : None
s3fs : None
scipy : None
sqlalchemy : 2.0.36
tables : None
tabulate : None
xarray : None
xlrd : None
xlsxwriter : None
zstandard : None
tzdata : 2024.2
qtpy : None
pyqt5 : None

[eicchen]

take

[eicchen]

I verified it in the release build but not on the main branch, try running it on the main branch, the root issue might have been fixed already

[eicchen]

I think this issue should be able to be closed

[camold]

I have tried to set up a clone of the main branch but it does not build on my machine locally. So I cannot easily test if the issue has been resolved already or not. Have you tried?

[chilin0525]

Thanks for raising the issue — it has been resolved on the main branch:

>>> df = pd.DataFrame([{"a": "foo", "b": "bar"}])
>>> df.duplicated(subset={"a"}) # raises error
0    False
dtype: bool

confirmed on 2.3.0:

>>> df = pd.DataFrame([{"a": "foo", "b": "bar"}])
>>> df.duplicated(subset={"a"}) # raises error
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/chilin/pandas-2.2.3/lib/python3.12/site-packages/pandas/core/frame.py", line 6961, in duplicated
    result = self[subset[0]].duplicated(keep)
                  ~~~~~~^^^
TypeError: 'set' object is not subscriptable

[chilin0525]

The problem in v2.3.0 raise from here:

pandas/pandas/core/frame.py

Line 6961 in 2cc3762

result = self[subset[0]].duplicated(keep)

The related PR(#59392) already changed and merge into main branch, and this issue has been classified under the 3.0 milestone, so I agree with @eicchen this issue should be closed.

pandas/pandas/core/frame.py

Line 6979 in c5457f6

result = self[next(iter(subset))].duplicated(keep)

[camold]

Thanks!