help with loop
On 12 Mar 2009, at 13:22, Richard.Cotton at hsl.gov.uk wrote:
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.
This is just sum(diff(x)), or even x[length(x)] - x[1].
I think rowSums gives what's intended, rowSums(diff( matrix(c(1,2,3,4,5,6),ncol=2) )) (but i'd give heads or tails as to whether this was an oversimplification of the real problem ) baptiste
_________________________ R-help at 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.