[R] given a mid-month date, get the month-end date

Gabor Grothendieck ggrothendieck at gmail.com
Mon Dec 19 17:58:49 CET 2005

The zoo package has a yearmon class with as methods which can be

dd <- Sys.Date()  # test data

as.Date(as.yearmon(dd), frac = 1)

as.yearmon converts the "Date" class date to a year and month of
class "yearmon" dropping the day and representing it internally in
a way consistent with "ts" class.

as.Date above then converts it back to "Date" class.
Since yearmon dates have no day (they are just a year and
a month) the frac argument is used to indicate what fraction
of the month to use as the day of the month so frac = 0 (the
default) would give the beginning of the month) and frac = 1
gives the end.

On 12/19/05, t c <quantpm at yahoo.com> wrote:
>  I have a vector of dates.
>  I wish to find the month end date for each.
>  Any suggestions?
>  e.g.
>  For 12/15/05, I want 12/31/05,
>  For 10/15/1995, I want 10/31/1995, etc
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