[R] only 0s may be mixed with negative subscripts

[Hasan Diwan]

On 13 February 2012 14:46, ilai <keren at math.montana.edu> wrote:
> The function you posted runs without error (on these 6 lines), but
> does not return anything that looks remotely like a sum, or cumsum of
> anything. Can you clarify what you are trying to do? I assume by "sum
> of every other row" you don't mean summing Time, X and Y for rows
> 1,3,5,..., ?

I'm trying to get a piecewise sum of every n rows in a given column in
this data set.
> For the sum of sens2[c(1,3,5,...),] for every column (assuming no NA's
> in the data) you could

I do format checking well before getting to this stage in the analysis.
>
>  (1:nrow(sens2) %% 2) %*% as.matrix(sens2)

That does not do what I want... Again, what it should return is a list
of the sum of the current and preceding row.
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