Note that "%Y-%m-%d" is the default format so you can omit it.
Perhaps you want something along these lines (modify formula
to get the precise numbering you like):
a$wk <- julian(a$date, as.Date("2008-01-01")) %/% 7
Also note %W can be used as a format string. See
?strptime for the codes.
R News 4/1 has an article about dates.
On Thu, Jun 5, 2008 at 11:46 PM, Andrew McFadden
<[EMAIL PROTECTED]> wrote:
> I all
>
> I am just trying to get the idea of a loop if statement for another
> purpose. I was going to label a new variable based on date ie first week
> 1, second week 2 etc. My code in bold is wrong but seems logical to me,
> could someone help.
>
> x <-
> rep(c(2660156,2663703,2658165,2659303,2661531,2660914),c(2,2,2,2,1,1))
> y <-
> rep(c(6476767,6475013,6475487,6479659,6477004,6476388),c(2,2,2,2,1,1))
> date <- rep(as.Date(c("2008-01-01","2008-01-14","2008-01-28"), format
> = "%Y-%m-%d"),c(4,4,2))
> a<-data.frame(x,y,date)
> a$wk<-rep(c(0),nrow(a))
> a
> set<-as.Date(c("2008-01-01"), format = "%Y-%m-%d")
> set
>
> for(i in a$date){
> if (a$date[i]>set & a$date[i]<set +7 ){a$wk<-1}else
> if (a$date[i]>set +7){a$wk<-2}else {a$wk<-3}
> }
> a
>
> Kind regards
>
> andy
>
> Andrew McFadden MVS BVSc
> Incursion Investigator
> Investigation & Diagnostic Centres - Wallaceville Biosecurity New
> Zealand Ministry of Agriculture and Forestry
>
> Phone 04 894 5600 Fax 04 894 4973 Mobile 029 894 5611 Postal address:
> Investigation and Diagnostic Centre- Wallaceville Box 40742 Ward St
> Upper Hutt
>
>
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