Well actually, what about that (Assuming mydata is a data frame)
tail( mydata, 1 ) - head( mydata, 1) since: (the second - the first) + (the third - the second) + (the fourth - the third) = the last - the first Romain Rafael Moral wrote:
Dear useRs, I'm trying to write a loop to sum my data in the following way: (the second - the first) + (the third - the second) + (the fourth - the third) + ... for each column. So, I wrote something like this: c <- list() for(i in 1:ncol(mydata)) { for(j in 2:nrow(mydata)) { c[[i]] <- sum(yc[j,i] - yc[(j-1),i]) }}} As for the columns it works pretty fine, but it only returns the last subtraction, however, I need the sum of all subtractions. Any ideas? Regards, Rafael.
-- Romain Francois Independent R Consultant +33(0) 6 28 91 30 30 http://romainfrancois.blog.free.fr ______________________________________________ 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.