On Thu, 2007-12-20 at 22:43 +0100, Johannes Graumann wrote:
> Hi all,
>
> Does anybody have a magic trick handy to isolate directly consecutive
> integers from something like this:
> c(1,2,3,4,7,8,9,10,12,13)
>
> The result should be, that groups 1-4, 7-10 and 12-13 are consecutive
> integers ...
>
> Thanks for any hints, Joh
Not fully tested, but here is one possible approach:
> Vec
[1] 1 2 3 4 7 8 9 10 12 13
Breaks <- c(0, which(diff(Vec) != 1), length(Vec))
> Breaks
[1] 0 4 8 10
> sapply(seq(length(Breaks) - 1),
function(i) Vec[(Breaks[i] + 1):Breaks[i+1]])
[[1]]
[1] 1 2 3 4
[[2]]
[1] 7 8 9 10
[[3]]
[1] 12 13
For a quick test, I tried it on another vector:
set.seed(1)
Vec <- sort(sample(20, 15))
> Vec
[1] 1 2 3 4 5 6 8 9 10 11 14 15 16 19 20
Breaks <- c(0, which(diff(Vec) != 1), length(Vec))
> Breaks
[1] 0 6 10 13 15
> sapply(seq(length(Breaks) - 1),
function(i) Vec[(Breaks[i] + 1):Breaks[i+1]])
[[1]]
[1] 1 2 3 4 5 6
[[2]]
[1] 8 9 10 11
[[3]]
[1] 14 15 16
[[4]]
[1] 19 20
HTH,
Marc Schwartz
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