David, Is this what you are looking for? library(lattice) df <- expand.grid(site=c("een","twee","drie","vier","vijf"), month=1:12) df$conc <- rnorm(dim(df)[1]) dotplot(month~conc|site,data=df)
HTH Gerrit ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.