thmsfuller...@gmail.com wrote:
Hello All,
sample() only sample on one variable x. But I'm interested in sampling
more than one variable without replacement.
Suppose I have 3 vectors x, y, z. I want to draw samples from all
three vectors such that the combination of the three elements in each
draw is not the same as any previous draws. I could use expand.grid to
generate a vector out of the three vectors. But when the number of
vectors are large and the number of elements in some vectors are
large, it will be infeasible to do so.
If you know there is a method on sampling on more than one variables,
would you please let me know? Thank you!
Can you give a reproducible example? Since you suggested the method that is
most reasonable, but it will not work in large cases, I suppose you'll have to
draw independently from each vector one at a time, then somehow concatenate the
results, perhaps as a character vector, even if the vectors are, say, integers.
Then repeat this process checking each time if your new vector is %in% the
vector.
There may be a much better way, too, see if anyone else responds.
Also, you'll have to think about what a unique sample is.
If
x <- 1:3
y <- 2:4 ,
is x = 2, y = 3 the same as x = 3, y = 2?
Good luck,
Erik
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