m <- matrix(1:25, nrow=5)
print(m)
rows <- m[c(1,3), ]
print(rows)
# run:
#
# [,1] [,2] [,3] [,4] [,5]
# [1,] 1 6 11 16 21
# [2,] 2 7 12 17 22
# [3,] 3 8 13 18 23
# [4,] 4 9 14 19 24
# [5,] 5 10 15 20 25
# [,1] [,2] [,3] [,4] [,5]
# [1,] 1 6 11 16 21
# [2,] 3 8 13 18 23
#
#