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

[Bert Gunter]

Please use R's help resources before posting.

help.search("difference") will give you your answer (?diff).

-- Bert Gunter
Genentech 

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On
Behalf Of dott
Sent: Monday, August 11, 2008 8:27 AM
To: r-help at r-project.org
Subject: [R] R-help? how to take difference in next two elements


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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