Period Resampling Master Issue

[jreback]

Various issue surrounding resampling with a PeriodIndex

• ENH: PeriodIndex resampling redux #12884 Return PeriodIndex if possible
• ERR: Resample pad on existing freq causes recursion error #12770 recursion error on existing freq (PeriodIndex count & size fix #12874)
• BUG: Count on resampled PeriodIndex fails #12774 count (PeriodIndex count & size fix #12874)
• BUG: Resample on empty Period-Indexed Series returns Datetime-Indexed Series #12868 empty PeriodIndex (PeriodIndex count & size fix #12874)
• Empty DataFrame with PeriodIndex doesn't maintain index type on resample #13212 empty dataframe (BUG: Empty PeriodIndex issues #13079)
• Panel resample by periods does not work in 0.17.1 for certain panels #11983 with Panels?
• API: resample with PeriodIndex default span (start/end convention) #7744 convention issues
• BUG: resample on PeriodIndex with 'W' causes recursion #12883 recursion with 'W' freq when upsampling (PeriodIndex count & size fix #12874)
• ohlc resampling returns a different type depending on upsampling vs downsampling #13083 ohlc resampling
• Resampling with NaT in PeriodIndex raises ValueError #13224 with NaT
• BUG: PeriodIndexGrouper fails with Grouper selection #14008 MultiIndex with TimeGrouper
• BUG: loffset not applied when using resample with agg() (GH13218) #14213 Verify loffset works.
• DEPR: remove freq attribute of Timestamp? #15146 Timestamp freq -> Period

[jreback]

cc @MaximilianR

[max-sixty]

I can't edit the post, but I think all apart from these are solved:

#12884 Return PeriodIndex if possible
#11983 with Panels?
#7744 convention issues

[jreback]

@MaximilianR really?

we would need verifying tests only then.

[max-sixty]

we would need verifying tests only then

They should all have tests based on the PRs. (Your commits closed the issues, not me). Or lmk if I'm missing something

[jreback]

those all looks like one issues

[jreback]

oh sorry - you said all apar from those - I checked the boxes :)

[max-sixty]

Adding to the list, size loses the Series name, after #13079:

In [4]: pd.Series([], name='test', index=pd.PeriodIndex([],freq='D')).resample('M').size()
Out[4]: Series([], Freq: M, dtype: int64)

EDIT: now fixed