Dear Contributors, I am back asking for help concerning the same type of dataset I was asking before, in a previous help request. I needed to sum data over subsample of three time series each of them made of 100 observations. The solution proposed were various, among which: db<-p dim( db ) <- c(25,4,3) db2 <- apply(db, c(2,3), sum) db3 <- t(apply(db2, 1, function(poff) 100-(100*abs(poff/sum(poff)-(1/3))) ) ) My request now is about the function at the end of the calculation in db3. IF instead of the difference from a number, here 1/3, I need to calculate the following difference: consider that db3 is a matrix 4x3, I need to calculate (db3[1,1] -db3[1,2])+(db3[1,1] -db3[1,3])*0.5 and store it to a cell, then (db3[1,2] -db3[1,1])+(db3[1,2] -db3[1,3])*0.5 and store it to a cell, then (db3[1,3] -db3[1,2])+(db3[1,3] -db3[1,2])*0.5 and store it to a cell, then repeat this for each of the four row of the same matrix. The resulting matrix should be composed of these distances. I need to repeat this for each of the subsamples. I realize that there arecalculations that are repeated but I did not find a strategy that does not require Francesca ---------------------------------- Francesca Pancotto, PhD Università di Modena e Reggio Emilia Viale A. Allegri, 9 40121 Reggio Emilia Office: +39 0522 523264 Web: https://sites.google.com/site/francescapancotto/ ---------------------------------- [[alternative HTML version deleted]]