identifying weeks (dates) that certain days (dates) fall into

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Thanks a lot, everyone!
Dimitri

On Tue, Aug 2, 2011 at 12:34 PM, Dennis Murphy <djmuser at gmail.com> wrote:

Hi:

You could try the lubridate package:

library(lubridate)
week(weekly$week)
week(july4)
[1] 27 27

week

function (x)
yday(x)%/%7 + 1
<environment: namespace:lubridate>

which is essentially Gabor's code :)

HTH,
Dennis

On Tue, Aug 2, 2011 at 7:36 AM, Dimitri Liakhovitski
<dimitri.liakhovitski at gmail.com> 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.
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?
Thank you!
--
Dimitri Liakhovitski
marketfusionanalytics.com

--
Dimitri Liakhovitski
marketfusionanalytics.com