Suppose I have some array, but the dimension is a priori unknown (not necessarily 3, as in the example below).
A=array(1:24, dim=c(2,3,4))
I also have an input vector with length equal to the dimension of this array
pos=c(2,1,3)
Based on this input vector, I want to return
A[1:2,1:1,1:3]
How can I do this automatically? In other words, what kind of data X do I have to pass to A[] so that R understands what I want.
For example, having X be a list does not work:
A[lapply(pos,function(x) 1:x)]
>Solution :
pos = lapply(pos, seq)
do.call(`[`, c(list(A), pos))
[,1] [,2] [,3]
[1,] 1 7 13
[2,] 2 8 14