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lhsDesign <- function(n, dimension, randomized=TRUE, seed=NULL){
# arguments : n = number of points
# dimension = number of variables
# randomized = logical for randomized or centered points
# seed = value of the random seed
# output : a list containing the arguments and the LHS design
# if no seed is provided in argument, choice of the seed for 'runif' and 'sample'
if (is.null(seed)){
seed <- as.numeric(Sys.time())
}
set.seed(seed)
# Randomized LHS: U[0,1]-sampling of n x dim values
if (randomized) ran = matrix(runif(n*dimension),nrow=n,ncol=dimension)
# Centered LHS
else ran = matrix(0.5,nrow=n,ncol=dimension)
x = matrix(0,nrow=n,ncol=dimension) # initializing matrix x
for (i in 1:dimension) {
idx = sample(1:n) # vector of permutations of [1 to n]
P = (idx-ran[,i]) / n # vecteur of probabilities
x[,i] <- P }
# Outputs:
return(list(n=n,dimension=dimension,design=x,randomized=randomized,seed=seed))
}
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