length(unique(ID)) Michael
On Fri, May 25, 2012 at 11:38 AM, Charles Determan Jr <deter...@umn.edu> wrote: > Hello, > > Simple question that I am stuck on and can't seem to find an answer in the > help files currently. I have a list which contains repeated ID's. I would > like to have R count the number of ID's. For example: > > ID=c(1,1,1,1,2,2,2,2,3,3,3,3) > as.data.frame(ID) > > Clearly, there are 3 groups. How would I have R give me the summary: > > ID > 3 > > Many thanks, > Charles > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
