This will give you 6 months after today. Use negative numbers to move backwards:
> d <- Sys.Date() > seq(d, length = 2, by = paste(6, "months"))[2] [1] "2009-07-21" On Wed, Jan 21, 2009 at 6:27 AM, Sergey Goriatchev <serg...@gmail.com> wrote: > Dear Gabor, > > Thanks for that! > Still, it is not really similar to how EDATE works. > With julian(Sys.Date(), Sys.Date() - 10) one moves 10 days back. > The problem is that I need to move by months, not by days, as months > have different number of days. > I need to come to the same day when I move backward or forward in > time, for example going back one month from today (21.01.2009) I need > to come to 21.12.2008. > I've read through your article in RNews 4/1 but still do not know how > to do what I need to do. > > Regards, > Sergey > > On Wed, Jan 21, 2009 at 10:44, Gabor Grothendieck > <ggrothendi...@gmail.com> wrote: >> See ?julian >> >>> julian(Sys.Date(), Sys.Date() - 10) # 10 >> [1] 10 >> attr(,"origin") >> [1] "2009-01-11" >> >> and R News 4/1. >> >> On Wed, Jan 21, 2009 at 4:37 AM, Sergey Goriatchev <serg...@gmail.com> wrote: >>> Hello, everyone >>> >>> I wonder if R has something similar to Excel function >>> EDATE(start_date; months) which returns a serial number of the date >>> that is the indicated number of months before of after the start date. >>> Example (the second column EDATE(first_column; -6)): >>> 01.01.1999 01.07.1998 >>> 02.02.1999 02.08.1998 >>> 06.03.1999 06.09.1998 >>> >>> I am working with a zoo object where the row names are dates and for >>> particular rows I need to find values that were recorded 6 months >>> before (or return NA if the date is before the timeseries start). >>> >>> Maybe someone knows a passable R function for that kind of operation? >>> >>> Thanks in advance for help! >>> >>> Best, >>> Sergey >>> >>> ______________________________________________ >>> R-help@r-project.org mailing list >>> https://stat.ethz.ch/mailman/listinfo/r-help >>> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html >>> and provide commented, minimal, self-contained, reproducible code. >>> >> > > > > -- > I'm not young enough to know everything. /Oscar Wilde > Experience is one thing you can't get for nothing. /Oscar Wilde > When you are finished changing, you're finished. /Benjamin Franklin > Tell me and I forget, teach me and I remember, involve me and I learn. > /Benjamin Franklin > Luck is where preparation meets opportunity. /George Patten > ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
