[R] Creating 2 week intervals (lubridate)

[David Winsemius]

On Oct 23, 2011, at 4:18 PM, <sparklegirl100 at hotmail.com> <sparklegirl100 at hotmail.com 
 > wrote:

>
> Hello,
> I have a list of dates in which I am going use for a time series  
> analysis. I want to break these dates up into 2 week intervals and  
> count the number of times a date appears in this interval.
> For example from Nov. 19, 2000 to Dec 2 ,2000 with the data listed  
> below I want to return
> Start_date		Count2000/11/19	4
> Date: 2000/11/20 2000/11/21  2000/11/19 2000/11/29
> My first approach was toa vector of the two week time periods (like  
> below) and then match my dates with the intervals. But this did not  
> work.
> DataInterval<-rep(NA, 316)
> TwoWeekint<-function(date) {     for (i in 1:316)        new.day<- 
> i*14        DataInterval[i]<-as.interval(new_period(days=new.day),  
> ymd("2000-11-17"))
>  }
> Thanks!

(I must note I was very much tempted to ignore this post because of  
the mail address.)

See if this helps:

findInterval(as.Date("2000-11-01")+0:60,
        seq(from =as.Date("2000-11-20"), to=as.Date("2000-12-31"),  
by="2 week")
             )
  [1] 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1  
1 2 2 2 2 2 2
[40] 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3 3 3 3 3 3


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-- 

David Winsemius, MD
West Hartford, CT