Dear Gabor, Fantastic! Thank you very much for your help, as always!
Regards, Sergey On Wed, Mar 3, 2010 at 12:24, Gabor Grothendieck <ggrothendi...@gmail.com> wrote: > Try this. as.Date(as.yearmon(today) - 6/12) gives the 1st of the > month 6 months ago and the remainder of that line moves ahead by d-1 > days if its the d-th day of the month now. > >> library(zoo) >> z <- zoo(0:399, as.Date("2009-06-01")+0:399) >> today <- Sys.Date(); today > [1] "2010-03-03" >> ago6mos <- as.Date(as.yearmon(today) - 6/12) - 1 + as.numeric(format(today, >> "%d")) >> window(z, index = ago6mos) > 2009-09-03 > 94 > > If we are at the last day of the month and 6 months ago that month has > fewer days than today's month then what to do is not well defined but > we resolve that here by just moving ahead d-1 days anyways. > > On Wed, Mar 3, 2010 at 6:07 AM, Sergey Goriatchev <serg...@gmail.com> wrote: >> Hello everyone >> >> I use zoo objects and I need to find a date 6 months before today's date. >> >> Example, today we have 3rd March 2010, I need to find the date 3rd >> September 2009. >> >> How could I do that, please? >> >> >> Regards, >> Sergey >> >> -- >> Simplicity is the last step of art./Bruce Lee >> The more you know, the more you know you don't know. >> >> ______________________________________________ >> 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. >> > -- Simplicity is the last step of art./Bruce Lee The more you know, the more you know you don't know. /Myself 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 Luck is where preparation meets opportunity. /George Patten Kniven skärpes bara mot stenen. ______________________________________________ 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.