[R] Assign date according to defined time interval

[arun]

Hi,

Please use ?dput() to show the dataset.  Also, it is not clear about how you store the time interval.
dat <- read.table(text="
GroupID        Date
1      1      10-Dec-12
2      1      11-Dec-12
3      2      13-Dec-12
4      2      15-Dec-12
5      3      06-Dec-12
6      3      19-Dec-12",sep="",header=TRUE,stringsAsFactors=FALSE)



 dat2 <- data.frame(Week=1:2, from= c("9-Dec-12", "16-Dec-12"), to=c("15-Dec-12","22-Dec-12"),stringsAsFactors=FALSE)

#Check ?findInterval()

res <- t(sapply(split(dat,dat$GroupID), function(x) {
                            x$Date <-as.Date(x$Date,"%d-%b-%y")
                             unsplit(lapply(split(dat2,dat2$Week),function(y) {
                                        y$from <- as.Date(y$from, "%d-%b-%y")
                                         y$to <- as.Date(y$to, "%d-%b-%y")
                                         sum(x$Date > y$from & x$Date <= y$to)}),
                                                    dat2$Week)
                          }))

colnames(res) <- paste0("Week",1:2)
 res
#  Week1 Week2
#1     2     0
#2     2     0
#3     0     1


A.K.










On Tuesday, October 15, 2013 6:24 PM, Weijia Wang <zeleehom at gmail.com> wrote:
Hi, I have something very interesting:

Say I have this:

GroupID         Date
1      1       10-Dec-12
2      1       11-Dec-12
3      2       13-Dec-12
4      2       15-Dec-12
5      3       06-Dec-12
6      3       19-Dec-12

Now, I have time interval,

week 1: from 9-Dec-12 to 15-Dec-12,

week 2: from 16-Dec-12 to 22-Dec-12, and so on.

Obviously, the 1st, 2nd, 3rd, 4th row falls to week 1, 5th rows should not
be counted, 6th row falls into week2.

Therefore, by GroupID, I will have

GroupID=1, Week1=2, Week2=0
GroupID=2, Week1=2, Week2=0
GroupID=3, Week1=0, Week2=1.

I just want to count the valid date that falls into a 7-day week interval,
and I shall have new variables for EACH WEEK, and the counts for dates that
fall into this week interval.

Can anyone please help me on programming this?

W

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