Hi Petr, Finally, I got the solution like you explained and I find another one like the following:
Cover <- tapply(cover[,3], cover[, c(1,2)], c) It is working great. Thanks for your help, Hamada -- View this message in context: http://r.789695.n4.nabble.com/Problem-with-a-Matrix-tp4455954p4456041.html Sent from the R help mailing list archive at Nabble.com. ______________________________________________ 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.
