An iterator that dynamically shuffles as you go along. That's really nice, I had never even thought of that. Thanks.
On Thu, Jun 13, 2019 at 10:11 AM Alex Herbert <alex.d.herb...@gmail.com> wrote: > > On 13/06/2019 17:56, Eric Barnhill wrote: > > On Thu, Jun 13, 2019 at 9:36 AM sebb <seb...@gmail.com> wrote: > > > >> > >> Rather than shuffle etc in place, how about various > >> iterators/selectors to return entries in randomised order? > >> [Or does that already exist?] > >> > > I am pretty sure random draws, and shuffling, are implemented with > > different algorithms. Though sampling without replacement the full length > > of the set would yield a shuffled set, I think there are more efficient > > ways to shuffle a set. > > Iterators to return a random draw *without* replacement over the full > length of the array? The iterator would dynamically shuffle the array on > each call to next() so could be stopped early or can be called > infinitely as if a continuous stream. Is that your idea? > > UniformRandomProvider rng = ...; > int[] big = new int[1000000]; > // > // Fill big with lots of data > // > IntIterator iter = ShuffleIterators.create(rng, big); > int x = iter.next(); > int y = iter.next(); > int z = iter.next(); > > This doesn't exist but it is easy to do. Memory requirements would > require a copy of the data, or it could be marked as destructive to the > input array order and shuffle in place. > > If you want a random draw *with* replacement then you can just call > nextInt(int) with the size of the array to pick something. > > > --------------------------------------------------------------------- > To unsubscribe, e-mail: dev-unsubscr...@commons.apache.org > For additional commands, e-mail: dev-h...@commons.apache.org > >
