[R] R-help? how to take difference in next two elements

[Gabor Grothendieck]

Here are a couple of ways:

> tail(a, -2) - head(a, -2)
[1]  2  5 -3
> c(ts(a) - lag(ts(a), -2))
[1]  2  5 -3


On Mon, Aug 11, 2008 at 11:26 AM, dott <dorothy99 at gmail.com> wrote:
>
> Hi,
>
> I'd like to take difference for a sequence a between a_i and a_i-2, for
> instance,
> a<-c(2,3,4,8,1)
> I need (2, 5, -3) as a result. If not using a for loop, can anyone help me?
> Thanks a lot.
>
> Dot
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