DEPR: QuarterBegin and BQuarterBegin return days that are not quarter beginnings

[nimishgautam]

In[43]: datetime(2014,10,10) + BQuarterBegin()
Out[43]: Timestamp('2014-12-01 00:00:00')

In[45]: datetime(2014,10,10) + QuarterBegin()
Out[45]: Timestamp('2014-12-01 00:00:00')

Expected output is 2015-01-01.
(Note QuarterEnd and BQuarterEnd do produce the expected output of 2014-12-31)

[jreback]

The default startingMonth is 3 (which may be wrong, their is a comment in the code to that effect).

You can get what you expect by using a startingMonth=1

In [66]: datetime.datetime(2014,10,10) + pd.offsets.BQuarterBegin(startingMonth=3)
Out[66]: Timestamp('2014-12-01 00:00:00')

In [67]: datetime.datetime(2014,10,10) + pd.offsets.BQuarterBegin(startingMonth=1)
Out[67]: Timestamp('2015-01-01 00:00:00')

If you'd like to investigate to see why this is would be appreciated.

I don't know when/how this was done this way.

[jreback]

If any of you have a comment about this:

cc @bjonen
cc @cancan101
cc @rockg
cc @MichaelWS

[MichaelWS]

I think I would prefer default QuarterBegin to be 1

[jreback]

agreed - seeing if anyone know why it is not 1 (and why 3)

[nimishgautam]

Just guessing, but there are a few countries whose fiscal years begin in March (month 3): http://en.wikipedia.org/wiki/Fiscal_year, but even then, the QuarterEnd and BQuarterEnd objects don't default to 3 to match.

[rockg]

I'm inclined to change this default to the standard quarter definition (month begins on 1, 4, 7, 10 and month ends on 3, 6, 9, 12). Any objections?

It is wrong and inconsistent now:

pd.Timestamp('11/2/2012', tz='US/Eastern') + pd.tseries.offsets.QuarterBegin()
Out[29]: Timestamp('2012-12-01 00:00:00-0500', tz='US/Eastern')
pd.Timestamp('11/2/2012', tz='US/Eastern') + pd.tseries.offsets.QuarterEnd()
Out[30]: Timestamp('2012-12-31 00:00:00-0500', tz='US/Eastern')

[rockg]

Related to #5307 probably.