[R] simple loop iteration

[Peter Ehlers]

Perhaps you're just looking for the diff() function?
See ?diff.

  -Peter Ehlers

On 2010-03-30 7:15, Niklaus Hurlimann wrote:
> Hi R mailing list,
>
> probably a very basic problem here, I try to do the following:
>
>> Q<-c(1,2,3)
>> P<-c(4,5,6)
>> A<- data.frame(Q,P)
>> A
>    Q P
> 1 1 4
> 2 2 5
> 3 3 6
>
> this is my simplified data.frame (matrix) now I try to create following
> loop for subtraction of element within the data.frame:
>
>> for(i in length(A[,"P"]-1){
>    delta[i]<- A[i,"P"]-A[i+1,"P"]
> }
>
> All I get is a vector of  the correct length but with no readings.
>
> Thanks for any help on this.
>
>
>
>
>
>
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-- 
Peter Ehlers
University of Calgary