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...ed both for creating a sample and for scrambling the order of a vector. Scrambling the order of a big vector wastes time. It would be nice to be able to tell sample() that we don't care about the order. Bill Dunlap TIBCO Software wdunlap tibco.com On Tue, Oct 17, 2017 at 10:55 AM, Pavel S. Ruzankin <ruzankin at math.nsc.ru> wrote: > Let us consider the current uniform sampling without replacement > algorithm. It resides in function do_sample in > https://svn.r-project.org/R/trunk/src/main/random.c > Its complexity is obviously O(n), where the sample is selected from 1...n,...

Let us consider the current uniform sampling without replacement algorithm. It resides in function do_sample in https://svn.r-project.org/R/trunk/src/main/random.c Its complexity is obviously O(n), where the sample is selected from 1...n, since the algorithm has to create a vector of length n. So when the sample size is much lesser than n, the algorithm is not effective. Algorithms with

> From: "Pavel S. Ruzankin" <ruzankin at math.nsc.ru> > Let us consider the current uniform sampling without replacement > algorithm. It resides in function do_sample in > https://svn.r-project.org/R/trunk/src/main/random.c > Its complexity is obviously O(n), where the sample is selected from > 1...