HI, how can use in the function below instead of ave sum? I would like to sum up breaks. Pox2 <- data.frame(ave(lsk0t50$Pox2, lsk0t50$ProfN, Fun=is.na(lsk0t50$Pox2))) Regards, Ulrich -- __________________________________________________ Ulrich Leopold MSc. Department of Physical Geography Institute for Biodiversity and Ecosystem Dynamics Faculty of Science University of Amsterdam Nieuwe Achtergracht 166 NL-1018WV Amsterdam Phone: +31-(0)20-525-7456 (7451 Secretary) Fax: +31-(0)20-525-7431 Email: uleopold at science.uva.nl http://www.frw.uva.nl/soil/Welcome.html Check us also out at: Netherlands Centre for Geo-ecological Research http://www.frw.uva.nl/icg -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._