I want to sample 6 letters from the total set of 26 n times so that each letter gets sampled exactly 3 times across all n times. How would I write this in R or python?
EDIT: I missed out one crucial criterion, each set of 6 letters should be unique. So each set of 6 letters should be sampled without replacement.
With your conditions you can have a maximum of 13 samples i.e. 26 * 3 / 6 = 13. Here's one way to get them -
set.seed(2)
m <- matrix(sample(rep(letters, 3)), nrow = 6)
m
[,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10] [,11] [,12] [,13]
[1,] "o" "j" "y" "a" "s" "a" "j" "g" "p" "x" "x" "p" "y"
[2,] "c" "h" "l" "e" "l" "z" "m" "f" "x" "n" "d" "v" "o"
[3,] "r" "g" "z" "m" "h" "p" "q" "v" "v" "a" "e" "c" "o"
[4,] "m" "l" "b" "w" "k" "n" "f" "s" "b" "u" "d" "h" "y"
[5,] "r" "u" "i" "u" "w" "e" "t" "f" "r" "w" "t" "t" "z"
[6,] "q" "q" "n" "i" "g" "s" "k" "k" "c" "j" "i" "d" "b"
table(m)
m
a b c d e f g h i j k l m n o p q r s t u v w x y z
3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3