Bad type hint for argument unique for DataFrameSchema

[sidpatelgit]

Describe the bug

DataFrameSchema says it accepts str for the argument unique, but if a string is provided, the validation crashes with ValueError: not enough values to unpack (expected 2, got 0).

Might be related to this issue.

• I have checked that this issue has not already been reported.
• I have confirmed this bug exists on the latest version of pandera.
• (optional) I have confirmed this bug exists on the main branch of pandera.

Code Sample, a copy-pastable example

import pandera as pa
import pandas as pd

df = pd.DataFrame({'alpha':[0,1],'beta':[2,3]})
schema = pa.DataFrameSchema(columns={'alpha':pa.Column(dtype=int),'beta':pa.Column(dtype=int)},unique='alpha',strict=True)
schema.validate(df)

If you change alpha in the example to a, it seems to work. So maybe the problem is strings with more than one character.

Expected behavior

If the type hint says it accept str, then if I provide str, the validation should run without crashing.

Desktop (please complete the following information):

• OSX 14.4 (23E214)
• Browser: chrome

[Jarek-Rolski]

I created pull request fixing the issue. #1817