DataFrame.loc[] accepts list[str]

[ndawe]

Describe the bug

DataFrame.loc[] should accept list[str] as stated in the pandas docs: "A list or array of labels, e.g. ['a', 'b', 'c']."

To Reproduce

import pandas as pd                                                             
                                                                                
df = pd.DataFrame([[1, 2], [4, 5], [7, 8]],                                     
                  index=['cobra', 'viper', 'sidewinder'],                       
                  columns=['max_speed', 'shield'])                              
                                                                                
df.loc[['viper', 'sidewinder']] 

$ mypy pd_test.py 
pd_test.py:7: error: Invalid index type "list[str]" for "_LocIndexerFrame[DataFrame]"; expected type "slice[Any, Any, Any] | ndarray[Any, dtype[integer[Any]]] | Index[Any] | list[int] | Series[int] | <6 more items>"  [index]
Found 1 error in 1 file (checked 1 source file)
1

Please complete the following information:

• OS: Linux
• OS Version: Ubuntu 24.04.2 LTS
• python version: 3.12.9
• version of type checker: mypy 1.15.0 (compiled: yes)
• version of installed pandas-stubs: 2.2.3.250308

[Dr-Irv]

df.loc[['viper', 'sidewinder']]

To avoid some ambiguities from a typing perspective, we recommend using one of the following 2 patterns:

df.loc[:, ['viper', 'sidewinder']]
df[['viper', 'sidewinder']]

[ndawe]

Those examples attempt to select columns, but df.loc[['viper', 'sidewinder']] selects labels along the index.

[Dr-Irv]

Those examples attempt to select columns, but df.loc[['viper', 'sidewinder']] selects labels along the index.

Then use df.loc[['viper', 'sidewinder'], :]

[ndawe]

Yes, and is it possible for the type declarations here to support .loc[Sequence]? If that's difficult because of ambiguity then I'm happy to switch to the df.loc[['viper', 'sidewinder'], :] pattern.

[Dr-Irv]

Yes, and is it possible for the type declarations here to support .loc[Sequence]? If that's difficult because of ambiguity then I'm happy to switch to the df.loc[['viper', 'sidewinder'], :] pattern.

Actually, yes. This revealed a bug. Need to change

pandas-stubs/pandas-stubs/core/frame.pyi

Line 187 in 69b833c

| list[Hashable]

from list[Hashable] to list[HashableT]

PR with tests welcome.

[shirzady1934]

@Dr-Irv I have made the required changes. Please review and let me know if anything else is needed. Thanks!