According to the definition in ?strptime (which is not the same as the ISO definition):
format(x, "%W") returns "Week of the year as decimal number (00–53) using Monday as the first day of week (and typically with the first Monday of the year as day 1 of week 1). The UK convention." The first day of 2008 is a Tuesday which means that 2008 starts in week 0. On Thu, Dec 11, 2008 at 2:31 PM, Hans W. Borchers <hwborch...@gmail.com> wrote: > Gabor Grothendieck <ggrothendieck <at> gmail.com> writes: > >> >> format(d, "%U") and format(d, "%W") give week numbers using >> different conventions. See ?strptime > > Gabor, > > the results of format(aDate, "W") appear to be incorrect anyway, see: > > format(as.Date("2008-01-01"), "%W") #-> "00" > > There is never a week 0, this should be week 1. > > format(Sys.Date(), "%W") #-> "49" > > but my business calendar says today's (Dec. 11, 2008) week is week 50 > which is what Brian Ripleys proposed 'strftime(x, "%V")' returns. > > There could be a format "%E" (not used up to now) for returning a > correct week number according to the European standard. > > Yours, Hans Werner > >> On Thu, Dec 11, 2008 at 7:43 AM, Gustaf Rydevik >> <gustaf.rydevik <at> gmail.com> wrote: >> > Hi all, >> > >> > Is there a simple function already implemented for getting the ISO >> > weeks of a Date object? >> > I couldn't find one, and so wrote my own function to do it, but would >> > appreciate a pointer to the "default" way. If a function is not yet >> > implemented, could the code below be of interest to submit to CRAN? >> > >> > Best Regards, >> > >> > Gustaf >> > >> > -------------------- >> >> ... [rest deleted] >> ______________________________________________ >> R-help <at> 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. >> >> > > ______________________________________________ > 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. > ______________________________________________ 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.