You did: > >> ID=c(1,1,1,1,2,2,2,2,3,3,3,3) > >> as.data.frame(ID) and I infer that you want the number of groups in each column of the data.frame. First, make an example of your data.frame D <- data.frame(ID, Name=rep(state.name[1:7],len=length(ID))) (note I use data.frame, not as.data.frame, so it gets the column names that I want). Now use sapply() (or the related vapply()):
> sapply(D, function(column)length(unique(column))) ID Name 3 7 Bill Dunlap Spotfire, TIBCO Software wdunlap tibco.com > -----Original Message----- > From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-project.org] On > Behalf > Of Charles Determan Jr > Sent: Friday, May 25, 2012 9:55 AM > To: Steve Friedman > Cc: r-help@r-project.org > Subject: Re: [R] count number of groups > > That works if I want a count of each group but I needed a count of the > number of groups. Michael answered that question with length(unique(ID)) > However, this doesn't supply a title, it is just a number. I need it to > still have the identifier 'ID'. > > Regards, > Charles > > On Fri, May 25, 2012 at 11:50 AM, Steve Friedman <skfgla...@gmail.com>wrote: > > > ?table > > On May 25, 2012 11:46 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. > >> > > > > [[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.
