[R] Counting indexes
ggrothendieck at gmail.com
Wed May 26 07:00:42 CEST 2010
This assumes that for a particular id they all occur together in a run:
> cbind(start = which(!duplicated(id)), end = which(!duplicated(id, fromLast = TRUE)))
[1,] 1 1
[2,] 2 3
[3,] 4 6
[4,] 7 7
[5,] 8 9
On Wed, May 26, 2010 at 12:14 AM, Robin Jeffries <rjeffries at ucla.edu> wrote:
> I have a vector of ID's like so,
> id <- c(1,2,2,3,3,3,4,5,5)
> I would like to create a [start,stop] pair of vectors that index the first
> and last observation per ID.
> For the ID list above, it would look like
> 1 1
> 2 3
> 4 6
> 7 7
> 8 9
> I haven't worked with indexes/data manipulation much in R, so any pointers
> would be helpful.
> Many thanks!
> -Robin Jeffries
> Dr.P.H. Candidate in Biostatistics
> UCLA School of Public Health
> rjeffries at ucla.edu
> [[alternative HTML version deleted]]
> R-help at r-project.org mailing list
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
More information about the R-help