Create an unbalanced block matrix

Question

Is there a general function to make block matrices in R, where the blocks are different sizes but the content of each block is the same?... something like this...

#block size 
bb <- c(2,3,4,2) 
dn <- rep(LETTERS[1:4], times = bb)
#block contents based on 1:16 sequence
matrix(c( 1, 1, 2, 2, 2, 3, 3, 3, 3, 4, 4,
          1, 1, 2, 2, 2, 3, 3, 3, 3, 4, 4, 
          5, 5, 6, 6, 6, 7, 7, 7, 7, 8, 8, 
          5, 5, 6, 6, 6, 7, 7, 7, 7, 8, 8,
          5, 5, 6, 6, 6, 7, 7, 7, 7, 8, 8,
          9, 9,10,10,10,11,11,11,11,12,12,
          9, 9,10,10,10,11,11,11,11,12,12,
          9, 9,10,10,10,11,11,11,11,12,12,
          9, 9,10,10,10,11,11,11,11,12,12,
         13,13,14,14,14,15,15,15,15,16,16,
         13,13,14,14,14,15,15,15,15,16,16), 
       byrow = TRUE, nrow = sum(bb), ncol = sum(bb), dimnames = list(dn, dn))

#    A  A  B  B  B  C  C  C  C  D  D
# A  1  1  2  2  2  3  3  3  3  4  4
# A  1  1  2  2  2  3  3  3  3  4  4
# B  5  5  6  6  6  7  7  7  7  8  8
# B  5  5  6  6  6  7  7  7  7  8  8
# B  5  5  6  6  6  7  7  7  7  8  8
# C  9  9 10 10 10 11 11 11 11 12 12
# C  9  9 10 10 10 11 11 11 11 12 12
# C  9  9 10 10 10 11 11 11 11 12 12
# C  9  9 10 10 10 11 11 11 11 12 12
# D 13 13 14 14 14 15 15 15 15 16 16
# D 13 13 14 14 14 15 15 15 15 16 16

... but without all the repetitive set up in the matrix function

Answer 1

Made my own function..

my_matrix <- function(x, b){
  n <- length(b)
  bb <- rep(1:4, times = b)
  xx <- matrix(NA, nrow = sum(b), ncol = sum(b))
  k <- 1
  for(i in 1:n){
    for(j in 1:n){
      xx[i==bb, j==bb] <- x[k]
      k <- k+1
    }
  }
  xx
}

my_matrix(x = 1:16, b = c(2,3,4,2))
#       [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10] [,11]
#  [1,]    1    1    2    2    2    3    3    3    3     4     4
#  [2,]    1    1    2    2    2    3    3    3    3     4     4
#  [3,]    5    5    6    6    6    7    7    7    7     8     8
#  [4,]    5    5    6    6    6    7    7    7    7     8     8
#  [5,]    5    5    6    6    6    7    7    7    7     8     8
#  [6,]    9    9   10   10   10   11   11   11   11    12    12
#  [7,]    9    9   10   10   10   11   11   11   11    12    12
#  [8,]    9    9   10   10   10   11   11   11   11    12    12
#  [9,]    9    9   10   10   10   11   11   11   11    12    12
# [10,]   13   13   14   14   14   15   15   15   15    16    16
# [11,]   13   13   14   14   14   15   15   15   15    16    16