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$wday
date.wday<-ifelse(date.wday==0,7,date.wday)
####If the date is in the beginning, or end of the year,
### does it fall into a week of the previous or next year?
Yn<-ifelse(date.yday<=(8-jan1.wday)&jan1.wday>4,Y-1,Y)
Yn<-ifelse(Yn==Y&((365+LY-date.yday)<(4-date.wday)),Y+1,Y)
##Set the week differently if the date is in the beginning,middle or
end of the year
Wn<-ifelse(
Yn==Y-1,
ifelse((jan1.wday==5|(jan1.wday==6 &LY.prev)),53,52),
ifelse(Yn==Y+1,1,(date.yday+(7-date.wday)+(jan1.wday-1))/7-(jan1.wday>4))
)
return(list(Year=Yn,ISOWeek=Wn))
}
--
Gustaf Rydevik, M.Sci.
tel: +46(0)703 051 451
address:Essingetorget 40,112 66 Stockholm, SE
skype:gustaf_rydevik
strftime(x, "%V") E.g. strftime(as.POSIXlt(Sys.Date()), "%V") is "50", and you might want as.numeric() on it. Note that this is OS-dependent, and AFAIR Windows does not have it. On Thu, 11 Dec 2008, Gustaf Rydevik wrote:> Hi all, > > Is there a simple function already implemented for getting the ISO > weeks of a Date object? > I couldn't find one, and so wrote my own function to do it, but would > appreciate a pointer to the "default" way. If a function is not yet > implemented, could the code below be of interest to submit to CRAN? > > Best Regards, > > Gustaf > > -------------------- > > getweek<-function(Y,M=NULL,D=NULL){ > > if(!class(Y)[1]%in%c("Date","POSIXt")) { > date.posix<-strptime(paste(c(Y,M,D),collapse="-"),"%Y-%m-%d") > } > if(class(Y)[1]%in%c("POSIXt","Date")){ > date.posix<-as.POSIXlt(Y) > Y<-as.numeric(format(date.posix,"%Y")) > M<-as.numeric(format(date.posix,"%m")) > D<-as.numeric(format(date.posix,"%d")) > } > > > LY<- (Y%%4==0 & !(Y%%100==0))|(Y%%400==0) > LY.prev<- ((Y-1)%%4==0 & !((Y-1)%%100==0))|((Y-1)%%400==0) > date.yday<-date.posix$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, ripley at stats.ox.ac.uk 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
format(d, "%U") and format(d, "%W") give week numbers using different conventions. See ?strptime 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 > > -------------------- > > 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 > > ______________________________________________ > 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. >
Perhaps you mean is that the definition ought be otherwise but at least according to one standard the definition is correct: http://www.opengroup.org/onlinepubs/009695399/functions/strptime.html On Thu, Dec 11, 2008 at 3:01 PM, Hans W. Borchers <hwborchers at gmail.com> wrote:> Gabor Grothendieck <ggrothendieck <at> gmail.com> writes: > >> >> 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. > > Yes I read that but it is still misleading and -- I think -- incorrect. > See <www.dateandtime.org/calendar> to find out that this is week 50 even > in the UK. > We would have had a lot of misplaced business meetings in our company if > the week numbers in Great Britain, Germany, and Sweden would actually be > different. > > Hans Werner > >> >> >> >> ... [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 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. >