Fixed values not repeated over column and row

Question

I want to create a matrix in R with a set number of variables (e.g. 1 to 10). Those variables should be randomly assigned over rows and columns BUT should not be repeated in eit

Answer 1

Unless I'm misunderstanding the problem, there's a much simpler way to create this shuffled matrix, without any loops or complicated conditional statements.

# number of rows and columns
n <- 10

# create ordered rows and columns
ordered.by.row <- matrix(1:n, n, n)
ordered.by.col <- matrix(1:n, n, n, byrow = T)

# offset the rows and columns relative to each other.
# no row or column has a repeated value, but the values are still ordered
offset <- (ordered.by.row + ordered.by.col) %% n + 1

# shuffle the columns, then shuffle the rows, this produces a randomized matrix
# 'shuffle.row' is the final, randomized matrix
set.seed(1222) # change this to change randomization
shuffle.col <- offset[,sample(1:n, n, replace = F)]
shuffle.row <- shuffle.col[sample(1:n, n, replace = F), ]

# verify solution
any(apply(shuffle.row, 1, function(r)any(duplicated(r)))) # FALSE
any(apply(shuffle.row, 2, function(r)any(duplicated(r)))) # FALSE

      [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
 [1,]    1   10    6    9    2    8    3    5    7     4
 [2,]    3    2    8    1    4   10    5    7    9     6
 [3,]    7    6    2    5    8    4    9    1    3    10
 [4,]    9    8    4    7   10    6    1    3    5     2
 [5,]   10    9    5    8    1    7    2    4    6     3
 [6,]    2    1    7   10    3    9    4    6    8     5
 [7,]    8    7    3    6    9    5   10    2    4     1
 [8,]    6    5    1    4    7    3    8   10    2     9
 [9,]    5    4   10    3    6    2    7    9    1     8
[10,]    4    3    9    2    5    1    6    8   10     7