Re: [R] jump in sequence

From: Martin Becker <martin.becker_at_mx.uni-saarland.de>
Date: Tue 30 Jan 2007 - 14:46:11 GMT

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



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