truncate dates to month start

[Jared Thompson]

I have a column of dates and I am trying to truncate them to be the first of the month for all the dates, for whatever month they are.

example:

dr = pd.date_range('20130101 09:12:56.1234', periods=3)

bs = pd.DataFrame(dr)

bs.columns = ['what']

bs

I can round to the Day as seen here:

bs.what.dt.round('D')

But if I Try to do Month, it fails:

bs.what.dt.round('MS')

ValueError: <MonthBegin> is a non-fixed frequency

Is there another way to do this?

I have been trying other means by trying to create a new column with a map and pulling out year, month etc.. but nothing I have tried yet has worked.

[Pratap Vardhan]

Does bs.what.dt.to_period('M').dt.to_timestamp() work for you?

[Jared Thompson]

Pretrap,

This will get me to where I need for now.

For the future I will continue to hunt down and see if ther is something that will just truncate down to the 1st of the month like 2016-11-01.

Thanks alot for your help.