One way is to use the following functions: ?unique ?aggregate ?merge For example, > x.df <- data.frame(Group=LETTERS[c(1, 1, 1, 2, 3)], Value=c(1, 1, 2, 2, 0)) > x.agg <- aggregate(x$Value, list(Group=x$Group), function(x){length(unique(x))}) > x.agg Group x 1 A 2 2 B 1 3 C 1 > x.merged <- merge(x.df, x.agg, by="Group") > x.merged Group Value x 1 A 1 2 2 A 1 2 3 A 2 2 4 B 2 1 5 C 0 1 >
On Dec 9, 2007 1:35 AM, christopher snow <[EMAIL PROTECTED]> wrote: > I have a table with two columns: > > A 1 > A 1 > A 2 > B 2 > C 0 > > I would like to produce a third column that contains the counts of each > unique combination of col1 and col2: > > A 1 2 > A 1 2 > A 2 1 > B 2 1 > C 0 1 > > How can I do this in R? > > Thanks in advance ... > > > -- > This message has been scanned for viruses and > dangerous content by MailScanner, and is > believed to be clean. > > ______________________________________________ > 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. > -- ====================================== T.K. (Tae-kyun) Kim Ph.D. student Department of Marketing Marshall School of Business University of Southern California ====================================== [[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.