BUG: FutureWarning when splitting a dataframe using `np.split`

[amanlai]

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

To reproduce it:

import numpy as np
import pandas as pd

df = pd.DataFrame({'a': [1, 2, 3]})
lst = np.split(df, 3)

Issue Description

The above code raises a FutureWarning:

FutureWarning: 'DataFrame.swapaxes' is deprecated and will be removed in a future version. Please use 'DataFrame.transpose' instead.

As far as I understand, np.split uses np.swapaxes which is raising this warning.

Expected Behavior

Not show a warning.

Installed Versions

python : 3.11.5
pandas : 2.2.0
numpy : 1.26.3

[VISWESWARAN1998]

swapaxes is called from shape_base.py in numpy package

[rhshadrach]

Thanks for the report - is there a reason you prefer to use np.swapaxes(df) over df.T?

[amanlai]

@rhshadrach the use case here is not np.swapaxes(df) itself, it's np.split(df), which apparently uses np.swapaxes under the hood.

[rhshadrach]

Ah, thanks @amanlai. On main, DataFrame.swapaxes has been removed and the OP gives the output:

[array([[1]]), array([[2]]), array([[3]])]

On 2.2.x, I am seeing

[   a
0  1,    a
1  2,    a
2  3]

cc @jorisvandenbossche @phofl @mroeschke