将3D数组转换为R中的矩阵

I'm trying to transform a 3D array into a matrix. I want the third dimension of the array to form the first row in the matrix, and this third dimension should be read by row (i.e., row 1, then row 2 etc... of dimension 3 should make up the first row of the matrix). I've given an example below, where the array has dimensions of 4, 3, and 5, and the resulting matrix has 5 rows and 12 columns. I have a solution below that achieves what I want, but it seems very cumbersome for large arrays (it first creates vectors from the elements of the array (by row), and then rbinds these to form the matrix). Is there a more elegant way to do this? Thanks in advance for any suggestions.I'm trying to transform a 3D array into a matri