How to sum values of array in each dimension into one matrix

Question

I've one array with three dimensions and want to sum up the values in each dimension and end up with one data matrix.

Here is one example:

array1 <- array(c(-5.5,6,3),dim = c(3,4,3))  

matrix <- matrix(NA, nrow=3, ncol=4)

matrix
       [,1]   [,2]  [,3]   [,4]
[1,]  -16.5  -16.5 -16.5  -16.5
[2,]   18      18    18     18
[3,]    9       9     9      9

Is it possible to do it somehow with a loop instead of using any apply function?

Thanks in advance!

Answer 1

Your question says you don't want to use an apply function, but in case you change your mind, you specify the margin as c(1, 2):

apply(array1, MARGIN=c(1, 2), sum)
#       [,1]  [,2]  [,3]  [,4]
# [1,] -16.5 -16.5 -16.5 -16.5
# [2,]  18.0  18.0  18.0  18.0
# [3,]   9.0   9.0   9.0   9.0