[R] help with loop

[baptiste auguie]

On 12 Mar 2009, at 13:22, Richard.Cotton at hsl.gov.uk wrote:

>> I'm trying to write a loop to sum my data in the following way:
>> (the second - the first) + (the third - the second) + (the fourth -
>> the third) + ...
>> for each column.
>
> This is just sum(diff(x)), or even x[length(x)] - x[1].
>

I think rowSums gives what's intended,

rowSums(diff( matrix(c(1,2,3,4,5,6),ncol=2) ))

(but i'd give heads or tails as to whether this was an  
oversimplification of the real problem )


baptiste


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