comparing the previous and next entry of a vector
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, J?rg Gro? <joerg at 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?
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