help with loop
This is a telescoping sum that can be calculated analytically as: (a[2] - a[1]) + ... + (a[n] - a[n-1]) = a[n] - a[1] On Thu, Mar 12, 2009 at 9:04 AM, Rafael Moral
<rafa_moral2004 at yahoo.com.br> 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.
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