Try this: > DF <- data.frame(x, nxt = c(tail(x, -1), NA), prv = c(NA, head(x, -1))) > DF x nxt prv 1 1 2 NA 2 2 3 1 3 3 4 2 4 4 5 3 5 5 2 4 6 2 6 5 7 6 NA 2 > subset(DF, nxt == 3 & prv == 1)$x [1] 2
On Sun, Jan 25, 2009 at 5:29 PM, Jörg Groß <jo...@licht-malerei.de> wrote: > Hi, > > I have a quit abstract problem, hope someone can help me here. > > I have a vector like this: > > > x <- c(1,2,3,4,5,2,6) > x > > [1] 1 2 3 4 5 2 6 > > now I want to get the number where the previous number is 1 and the next > number is 3 > (that is the 2 at the second place) > > I tried something with tail(x, -1) ... > with that, I can check the next number, but how can I check the previous > number? > > ______________________________________________ > 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. > ______________________________________________ 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.
