# Re: [R] Recursive decreasing sequences

From: Dimitrios Rizopoulos <Dimitris.Rizopoulos_at_med.kuleuven.be>
Date: Fri 20 Oct 2006 - 20:25:11 GMT

try this:

start.val <- 2
end.val <- 6500
system.time(res <- unlist(lapply(start.val:end.val, ":", to = end.val)))

I hope it helps.

Best,
Dimitris

Dimitris Rizopoulos
Ph.D. Student
Biostatistical Centre
School of Public Health
Catholic University of Leuven

```Tel: +32/(0)16/336899
Fax: +32/(0)16/337015
Web: http://med.kuleuven.be/biostat/
http://www.student.kuleuven.be/~m0390867/dimitris.htm

```

Quoting Julian Burgos <jmburgos@u.washington.edu>:

> Hello fellow R's,
>
> I'm sure there must be an easy way to do this. But after digging in the
> documentation and thinking about it for a while I couldn't figure it
> out. I need to get a decreasing recursive vector in. I mean something
> like this: if starting at 2, and ending at 6, the vector should be
>
> 2 3 4 5 6 3 4 5 6 4 5 6 5 6 6
>
> An easy way would be to do this
>
> x <- integer(0)
> for (i in 5) x <- c(x, i:5)
>
> But I need to create really long vectors (where the ending value is in
> the order of 6500) , and using loops is way to slow. I'm looking for a
> vectorized method. Any help will be welcomed.
>
> Julian
>
> Julian M. Burgos
>
> Fisheries Acoustics Research Lab
> School of Aquatic and Fishery Science
> University of Washington
>
> 1122 NE Boat Street
> Seattle, WA 98105
>
> Phone: 206-221-6864
>
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