How to take many samples of 10 from a large list, without replacement overall

Question

I've got a large set of data (20,000 data points), from which I want to take repeated samples of 10 data points. However, once I've picked those 10 data points, I want them to not be picked again.

I've tried using the sample function, but it doesn't seem to have an option to sample without replacement over multiple calls of the function. Is there a simple way to do this?

Answer 1

You could call sample once on the entire data set to permute it. Then when you want to get a sample you could grab the first 10. If you want another sample grab the next 10. So on and so forth.

Answer 2

Dason's thought, implemented in R:

sample <- split(sample(datapoints), rep(1:(length(datapoints)/10+1), each=10))
sample[[13]] # the thirteenth sample

Answer 3

This should work:

x <- rnorm(20000)
x.copy <- x
samples <- list()
i <- 1
while (length(x) >= 10){
    tmp <- sample(x, 10)
    samples[[i]] <- tmp
    i <- i+1
    x <- x[-match(tmp, x)]
}

table(unlist(samples) %in% x.copy)

However, I don't think that's the most elegant solution...