pcscorebootstrapdata <-
function(dat, bootrep, statistic, bootmethod = c("st", "sm", "mvn", "stiefel"), smo)
{
dat = t(dat)
n = dim(dat)[1]
p = dim(dat)[2]
boot = matrix(, p, bootrep)
bootdataarray = array(, dim = c(p, n, bootrep))

data = scale(dat, center = TRUE, scale = FALSE)
meandata = matrix(rep(as.matrix(colMeans(dat)), n), p, n)

dummy = svd(data)
U = dummy$u
D = diag(dummy$d)
V = dummy$v
if(bootmethod == "st")
{
for(b in 1:bootrep)
{
drawU = U[sample(1:n, n, replace = TRUE), ]
bootdata = t(drawU%*%D%*%t(V)) + meandata
bootdataarray[,,b] = bootdata
boot[,b] = centre(bootdata, type = statistic)
}
}
if(bootmethod == "sm")
{
for(b in 1:bootrep)
{
drawU = U[sample(1:n, n, replace = TRUE), ] + mvrnorm(n, rep(0, min(p, n)), var(U) * smo)
bootdata = t(drawU%*%D%*%t(V)) + meandata
bootdataarray[,,b] = bootdata
boot[,b] = centre(bootdata, type = statistic)
}
}
if(bootmethod == "mvn")
{
for(b in 1:bootrep)
{
drawU <- mvrnorm(n, colMeans(U), var(U))
bootdata = t(drawU%*%D%*%t(V)) + meandata
bootdataarray[,,b] = bootdata
boot[,b] = centre(bootdata, type = statistic)
}
}
if(bootmethod == "stiefel")
{
for(b in 1:bootrep)
{
X <- mvrnorm(n, colMeans(U), var(U))
tmp <- eigen(t(X)%*%X)
drawU = (X%*%(tmp$vec%*%sqrt(diag(1/tmp$val))%*%t(tmp$vec)))[sample(1:n,n,replace=TRUE),]
bootdata = t(drawU%*%D%*%t(V)) + meandata
bootdataarray[,,b] = bootdata
boot[,b] = centre(bootdata, type = statistic)
}
}
return(list(bootdata = bootdataarray, meanfunction = boot))
}