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

[Chuck Cleland]

On 8/11/2008 11:26 AM, dott 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

a <- c(2,3,4,8,1)

diff(a, lag=2)
[1]  2  5 -3

?diff

-- 
Chuck Cleland, Ph.D.
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