[R] identifying weeks (dates) that certain days (dates) fall into

[David Winsemius]

The findInterval function should surely be tried in some form or  
another.

On Aug 2, 2011, at 10:36 AM, Dimitri Liakhovitski wrote:

> Hello!
>
> I have dates for the beginning of each week, e.g.:
> weekly<-data.frame(week=seq(as.Date("2010-04-01"),
> as.Date("2011-12-26"),by="week"))
> week  # each week starts on a Monday
>
> I also have a vector of dates I am interested in, e.g.:
> july4<-as.Date(c("2010-07-04","2011-07-04"))
>
> I would like to flag the weeks in my weekly$week that contain those 2
> individual dates.

 > findInterval(july4, weekly$week)
[1] 14 66   # works "out of the box"

Provides an index you cna use with weekly$week

> I can only think of a very clumsy way of doing it:
>
> myrows<-c(which(weekly$week==weekly$week[weekly$week>july4[1]][1]-7),
> 	which(weekly$week==weekly$week[weekly$week>july4[2]][1]-7))
> weekly$flag<-0
> weekly$flag[myrows]<-1
>
> It's clumsy - because actually, my vector of dates of interest (july4
> above) is much longer.
> Is there maybe a more elegant way of doing it?

-- 

David Winsemius, MD
West Hartford, CT