A slightly simpler version is format(Sys.Date(), "%V")
On Thu, 11 Dec 2008, Prof Brian Ripley wrote:
strftime(x, "%V") E.g. strftime(as.POSIXlt(Sys.Date()), "%V") is "50", and you might want as.numeric() on it. Note that this is OS-dependent, and AFAIR Windows does not have it. On Thu, 11 Dec 2008, Gustaf Rydevik 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 -------------------- getweek<-function(Y,M=NULL,D=NULL){ if(!class(Y)[1]%in%c("Date","POSIXt")) { date.posix<-strptime(paste(c(Y,M,D),collapse="-"),"%Y-%m-%d") } if(class(Y)[1]%in%c("POSIXt","Date")){ date.posix<-as.POSIXlt(Y) Y<-as.numeric(format(date.posix,"%Y")) M<-as.numeric(format(date.posix,"%m")) D<-as.numeric(format(date.posix,"%d")) } LY<- (Y%%4==0 & !(Y%%100==0))|(Y%%400==0) LY.prev<- ((Y-1)%%4==0 & !((Y-1)%%100==0))|((Y-1)%%400==0) date.yday<-date.posix$yday+1 jan1.wday<-strptime(paste(Y,"01-01",sep="-"),"%Y-%m-%d")$wday jan1.wday<-ifelse(jan1.wday==0,7,jan1.wday) date.wday<-date.posix$wday date.wday<-ifelse(date.wday==0,7,date.wday) ####If the date is in the beginning, or end of the year, ### does it fall into a week of the previous or next year? Yn<-ifelse(date.yday<=(8-jan1.wday)&jan1.wday>4,Y-1,Y) Yn<-ifelse(Yn==Y&((365+LY-date.yday)<(4-date.wday)),Y+1,Y) ##Set the week differently if the date is in the beginning,middle or end of the year Wn<-ifelse( Yn==Y-1, ifelse((jan1.wday==5|(jan1.wday==6 &LY.prev)),53,52), ifelse(Yn==Y+1,1,(date.yday+(7-date.wday)+(jan1.wday-1))/7-(jan1.wday>4)) ) return(list(Year=Yn,ISOWeek=Wn)) } -- Gustaf Rydevik, M.Sci. tel: +46(0)703 051 451 address:Essingetorget 40,112 66 Stockholm, SE skype:gustaf_rydevik-- Brian D. Ripley, [EMAIL PROTECTED] Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595
-- Brian D. Ripley, [EMAIL PROTECTED] Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595 ______________________________________________ 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.
