[R] jump in sequence
Martin Becker
martin.becker at mx.uni-saarland.de
Tue Jan 30 15:46:11 CET 2007
Adrian DUSA wrote:
> Dear list,
>
> This should be a simple one, I just cannot see it.
> I need to generate a sequence of the form:
> 4 5 6 13 14 15 22 23 24
>
> That is: starting with 4, make a 3 numbers sequence, jump 6, then another 3
> and so on.
> I can create a whole vector with:
> myvec <- rep(rep(c(F, T, F), rep(3, 3)), 3)
>
> Then see which are TRUE:
> which(myvec)
> [1] 4 5 6 13 14 15 22 23 24
>
>
> I'd like to avoid creating the whole vector if possible; for very large ones
> it can be time consuming. There should be a way to only create the proper
> indexes...
>
>
Maybe:
n=10
3+rep(1:3,times=n)+9*rep(0:(n-1),each=3)
> Thanks for any hint,
> Adrian
>
>
Regards,
Martin
More information about the R-help
mailing list