> arr<-1:72
> dim(arr)<-c(2,4,3,3)
> apply(arr,1:2,sum)
[,1] [,2] [,3] [,4]
[1,] 297 315 333 351
[2,] 306 324 342 360
> apply(arr,3:4,sum)
[,1] [,2] [,3]
[1,] 36 228 420
[2,] 100 292 484
[3,] 164 356 548
>
apply(arr,1:2,sum)
will sum all elements arr(i1,i2,..)
for each single combination of the first and the second index
over all possible combinations of the third and fourth index.
On 5/27/2011 12:06 AM, marco milella wrote:
> Hi to everybody
> I have an array with dimensions 2,4,3,3.
> Wanting to sum the matrices in the first two dimensions, I'm trying to use
> the "apply" function, but with no results. Have to say I'm quite new with R
> syntax.
> tx in advance
>
> marco
>
> [[alternative HTML version deleted]]
>
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