Hadley and Dennis: THANK YOU THANK YOU! This is exactly what I was looking for.
Ryan On Wed, Jan 26, 2011 at 5:27 AM, Dennis Murphy <djmu...@gmail.com> wrote: > > Hi: > > > > Here are two more candidates, using the plyr and data.table packages: > > > > library(plyr) > > ddply(X, .(x, y), function(d) length(unique(d$z))) > > x y V1 > > 1 1 1 2 > > 2 1 2 2 > > 3 2 3 2 > > 4 2 4 2 > > 5 3 5 2 > > 6 3 6 2 > > > > The function counts the number of unique z values in each sub-data frame > > with the same x and y values. The argument d in the anonymous function is > a > > data frame object. > > Another approach is to use the much faster count function: > > count(unique(X)) > > Hadley > > -- > Assistant Professor / Dobelman Family Junior Chair > Department of Statistics / Rice University > http://had.co.nz/ > -- Ryan Utz Postdoctoral research scholar University of California, Santa Barbara (724) 272 7769 [[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.
