Hallo!

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@ucla.edu
530-624-0428

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