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
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