On 25-Jan-09 22:29:25, Jörg Groß 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?
x <- c(1,2,3,4,5,2,6) x0 <- x[1:(length(x)-2)] x1 <- x[3:(length(x))] x[which((x0==1)&(x1==3))+1] # [1] 2 Or, changing the data: x <- c(4,5,1,7,3,2,6,9,8) x0 <- x[1:(length(x)-2)] x1 <- x[3:(length(x))] x[which((x0==1)&(x1==3))+1] # [1] 7 Ted. -------------------------------------------------------------------- E-Mail: (Ted Harding) <ted.hard...@manchester.ac.uk> Fax-to-email: +44 (0)870 094 0861 Date: 25-Jan-09 Time: 22:47:15 ------------------------------ XFMail ------------------------------ ______________________________________________ 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.
