finding the last day of the month
On Mon, Nov 8, 2010 at 7:06 AM, Benjamin Williams <ben at bwmcct.com> wrote:
Dear R Help,
I am trying to get fields showing the last day of each month for a monthly
closing project. ?In order to find the last day of the previous month, I
subtract the number of days from the current month. For all months my code
works; however, for October, my code doesn't work...it returns
2010-09-*29* instead
of 2010-09-*30*.
format(strptime("2010-10-31",
"%Y-%m-%d")-(as.numeric(format(as.Date("2010-10-31"),"%d"))*24*3600),"%Y-%m-%d")
There are many ways to do this but here is one using as.yearmon in zoo. This converts the Date variable, today, to "yearmon" class which is a year and a fraction representing a month. Then it converts it back to "Date" class using frac = 1 which means all the way to the end of the month (frac = 0, the default, means 1st of month, etc.):
library(zoo) today <- Sys.Date() as.Date(as.yearmon(today), frac = 1)
[1] "2010-11-30" If you are trying to show monthly data another option might be just to not show the day at all:
format(as.yearmon(today))
[1] "Nov 2010"
# or without yearmon format(today, "%b %Y")
[1] "Nov 2010"
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