everyone! I have a very straight problem. I have a three dimensional array called w , like this:
> w
, , 1
[,1] [,2] [,3]
[1,] 0.5 0.5 0.5
[2,] 0.5 0.5 0.5
, , 2
[,1] [,2] [,3]
[1,] 0.1 0.1 1.0
[2,] 0.5 0.5 0.5
Now, it is just a representation , so this is not the actual data.
The thing is that I have add together the elements from the third dimensions, like w[1, 1, 1] + w[1, 1, 2] + w[1, 1, 3]
, but I don't know how many members the third dimension will have. I cannot do it in a for loop because it is within a nested for loop already (two for loops).
So, I basically have to add together w[, , 1] + w[, , 2] + w[, , 3]....
I tried something like
for (k in 1:dims(w)[3]) # it is one of the for loops
lapply(w[, , k], '+')
but it only prints the w[, , 1]
and that is it.
In c++, I think you would simply write y += w[, , n].
I would really appreciate some thoughts on how I should approach this or maybe a solution :).
*edit: a very embarrassing typo.
Looks like this does what you want:
# sample data
w<-array(sample(1:4),dim=c(3,3,3))
# sum over dimensions 1 and 2
apply(w, MARGIN=c(1, 2), sum)
Hope this helps!
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