ENH: add np.nan* funcs to cython_table
State: closed

- [x] closes #19629
- [x] tests added / passed
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry

This PR ensures that ``Series.agg`` can correctly take np.nan* funcs as inputs, e.g.:

```python
>>> pd.Series([1,2,3,4]).agg(np.nansum)
10
```

Previously that operation returned a Series. See #19629 for details.

Tests are added through the use of ``_get_cython_table_params`` in the parametrisation of ``test_agg_cython_table`` test function in ``series/test_apply``/``frame/test_apply``.

Labels:
name: Enhancement
name: Reshaping
description: Concat, Merge/Join, Stack/Unstack, Explode

Comments:
The failure is caused by a bug introduced in #21224. A fix has been proposed in #22110.
# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/22109?src=pr&el=h1) Report
> Merging [#22109](https://codecov.io/gh/pandas-dev/pandas/pull/22109?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/da9d85122a5b36b89fffa8f86ef768db20fc64c0?src=pr&el=desc) will **not change** coverage.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/22109/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/22109?src=pr&el=tree)

```diff
@@           Coverage Diff           @@
##           master   #22109   +/-   ##
=======================================
  Coverage   92.22%   92.22%           
=======================================
  Files         169      169           
  Lines       51261    51261           
=======================================
  Hits        47277    47277           
  Misses       3984     3984
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.66% <ø> (ø)` | :arrow_up: |
| #single | `42.23% <ø> (ø)` | :arrow_up: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/22109?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/base.py](https://codecov.io/gh/pandas-dev/pandas/pull/22109/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvYmFzZS5weQ==) | `97.61% <ø> (ø)` | :arrow_up: |

------

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so couple of things on this. I don't the the additional functions are actually tested when run in pandas/tests/frame/test_apply.py. Its also very hard to see as the ``ids`` are not specified when actually running these tests, can you fixup?
@topper-123 can you rebase
can you rebase
Hello @topper-123! Thanks for updating the PR.

 - There are no PEP8 issues in the file [`pandas/core/base.py`](https://github.com/topper-123/pandas/blob/7080d24bbb633449749979f1d55ad5e9320e00b9/pandas/core/base.py) !


Rebased.

Also, there were xfailed tests in ``test_agg_category_nansum`` that now pass. They also just use the fixture from conftest.fy now which is simpler. Not sure if the test should be just deleted.
thanks!