?diff > x ID LENGTH DIFF 1 1 10 NA 2 2 15 5 3 3 20 5 4 4 12 -8 5 5 18 6 > x <- x[,-3] > x ID LENGTH 1 1 10 2 2 15 3 3 20 4 4 12 5 5 18 > x$DIFF <- c(NA, diff(x$LENGTH) ) > x ID LENGTH DIFF 1 1 10 NA 2 2 15 5 3 3 20 5 4 4 12 -8 5 5 18 6
On Tue, May 5, 2009 at 7:00 PM, Mark Na <mtb...@gmail.com> wrote: > Dear R-helpers, > > I have a dataframe with several columns, one of which is called LENGTH. > > I would like to make a new column called DIFF containing the value of > LENGTH minus LENGTH in the previous row, like this: > > ID LENGTH DIFF > 1 1 10 NA > 2 2 15 5 > 3 3 20 5 > 4 4 12 -8 > 5 5 18 6 > > I'd like to think there are "relative subscripts" in R but I can't > find any reference to such a thing. > > Any help solving this problem would be much appreciated, thanks! > > Mark Na > > ______________________________________________ > 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<http://www.r-project.org/posting-guide.html> > and provide commented, minimal, self-contained, reproducible code. > -- Jim Holtman Cincinnati, OH +1 513 646 9390 What is the problem that you are trying to solve? [[alternative HTML version deleted]] ______________________________________________ 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.
