I have two directories https://echange-fichiers.inra.fr/get?k=AcHKdNI4No44GEsj7PK with 12 (global maps)binary files in each.I used the code given below to calculate the spatial correlation between these files and it worked well(the output is a global correlation map). I wonder if there is a simple way to calculate RMSE and bias along with cor.so finally we get three outputs (bias map,RMSE map,cor map) instead of only(cor map). Could anyone tell me how to add the RMSE function written below the code of Corr so that When I run the code.I get both RMSE map,corr map. RMSE function RMSE <- function(obs, sat){ sqrt(mean((obs-sat)^2, na.rm=T)) } Corr code dir1 <- list.files("D:\\2010\\data\\monthly", "*.bin", full.names TRUE) dir1<- mixedsort(dir1) dir2 <- list.files("D:\\RE01\\MIR_CLF3MD\\2010\\final-2010", "*.envi", full.names = TRUE) dir2<- mixedsort(dir2) file_tot<-array(dim=c(1440,720,12,2)) for(i in 1:length(dir1)){ file_tot[,,i,1] <- readBin(dir1[i], numeric(), size = 4 ,n = 1440 * 720 , signed = T) file_tot[,,i,2] <- readBin(dir2[i], numeric(), size = 4 ,n = 1440 * 720 , signed = T) } resultsr<-apply(file_tot,c(1,2),function(x){cor(x[,1],x[,2])}) to.write = file(paste("C:\\corrCCIandSMOS2010.bin",sep=""),"wb") writeBin(as.double(resultsr), to.write, size = 4) I am gratefull for any ideas -- View this message in context: http://r.789695.n4.nabble.com/How-to-add-a-function-to-another-written-code-tp4656499.html Sent from the R help mailing list archive at Nabble.com.