BUG: sort_values with ascending=None and key!=None raises exception

[gshimansky]

• I have checked that this issue has not already been reported.

• I have confirmed this bug exists on the latest version of pandas.

• (optional) I have confirmed this bug exists on the master branch of pandas.

---

Note: Please read this guide detailing how to provide the necessary information for us to reproduce your bug.

Code Sample, a copy-pastable example

import pandas as pd

def do_nothing(value):
    return value

df = pd.DataFrame(
    {
        "col1": [2, 51, 17],
        "col2": [5.5, 3.3, 4.4],
        "col3": ["a", "b", "c"],
    },
)
print(df)
df1 = df.sort_values(by=["col1"], ascending=None, key=do_nothing)
print(df1)

Problem description

Output is

   col1  col2 col3
0     2   5.5    a
1    51   3.3    b
2    17   4.4    c
Traceback (most recent call last):
  File "sort_values_test9.py", line 14, in <module>
    df1 = df.sort_values(by=["col1"], ascending=None, key=do_nothing)
  File "/home/gregory/work/miniconda3/envs/modin/lib/python3.8/site-packages/pandas/core/frame.py", line 5464, in sort_values
    indexer = nargsort(
  File "/home/gregory/work/miniconda3/envs/modin/lib/python3.8/site-packages/pandas/core/sorting.py", line 354, in nargsort
    return nargsort(
  File "/home/gregory/work/miniconda3/envs/modin/lib/python3.8/site-packages/pandas/core/sorting.py", line 368, in nargsort
    return items.argsort(ascending=ascending, kind=kind, na_position=na_position)
  File "/home/gregory/work/miniconda3/envs/modin/lib/python3.8/site-packages/pandas/core/arrays/base.py", line 583, in argsort
    ascending = nv.validate_argsort_with_ascending(ascending, args, kwargs)
  File "/home/gregory/work/miniconda3/envs/modin/lib/python3.8/site-packages/pandas/compat/numpy/function.py", line 150, in validate_argsort_with_ascending
    validate_argsort_kind(args, kwargs, max_fname_arg_count=3)
  File "/home/gregory/work/miniconda3/envs/modin/lib/python3.8/site-packages/pandas/compat/numpy/function.py", line 67, in __call__
    validate_args_and_kwargs(
  File "/home/gregory/work/miniconda3/envs/modin/lib/python3.8/site-packages/pandas/util/_validators.py", line 205, in validate_args_and_kwargs
    validate_kwargs(fname, kwargs, compat_args)
  File "/home/gregory/work/miniconda3/envs/modin/lib/python3.8/site-packages/pandas/util/_validators.py", line 149, in validate_kwargs
    _check_for_default_values(fname, kwds, compat_args)
  File "/home/gregory/work/miniconda3/envs/modin/lib/python3.8/site-packages/pandas/util/_validators.py", line 65, in _check_for_default_values
    raise ValueError(
ValueError: the 'axis' parameter is not supported in the pandas implementation of argsort()

Function validate_argsort_with_ascending inserts a value for ascending argument in case it is None, but later this value is considered as a value of axis parameter for some reason. This leads to an exception instead of a normal operation.

Expected Output

Output of pd.show_versions()

[paste the output of pd.show_versions() here leaving a blank line after the details tag]

INSTALLED VERSIONS

commit : 2cb9652
python : 3.8.6.final.0
python-bits : 64
OS : Linux
OS-release : 5.4.0-72-generic
Version : #80-Ubuntu SMP Mon Apr 12 17:35:00 UTC 2021
machine : x86_64
processor : x86_64
byteorder : little
LC_ALL : None
LANG : en_US.UTF-8
LOCALE : en_US.UTF-8

pandas : 1.2.4
numpy : 1.19.5
pytz : 2021.1
dateutil : 2.8.1
pip : 21.0.1
setuptools : 49.6.0.post20210108
Cython : None
pytest : 6.2.3
hypothesis : None
sphinx : 3.5.4
blosc : None
feather : 0.4.1
xlsxwriter : None
lxml.etree : 4.6.3
html5lib : None
pymysql : None
psycopg2 : None
jinja2 : 2.11.3
IPython : 7.20.0
pandas_datareader: None
bs4 : 4.9.3
bottleneck : None
fsspec : 0.8.5
fastparquet : None
gcsfs : None
matplotlib : 3.2.2
numexpr : 2.7.2
odfpy : None
openpyxl : 3.0.7
pandas_gbq : 0.15.0
pyarrow : 1.0.0
pyxlsb : None
s3fs : None
scipy : 1.6.2
sqlalchemy : 1.4.8
tables : 3.6.1
tabulate : None
xarray : 0.17.0
xlrd : 2.0.1
xlwt : None
numba : None

[phofl]

Hi, thanks for your report.

ascending should either be a bool or a list of bool, not None. This conversion is done to ensure compatibility with numpy.

[jreback]

does this raise the same on master? I think we merged a change to make this more informative

[phofl]

No same error

[phofl]

We could validate if ascending is not None maybe, but this would break some peoples code probably