Hi Alex,
I also don't have a use case for this right now. What about creating a JIRA
issue to wait to see if someone has the need for this feature? Maybe users
will confirm they need it, or provide other suggestions?
-Bruno
On Tue, 6 Dec 2022 at 15:36, Alex Herbert <alex.d.herb...@gmail.com> wrote:
> Currently the [rng] sampler package can only shuffle primitive int[]
> arrays:
>
> o.a.c.rng.sampling.PermutationSampler:
>
> public static void shuffle(UniformRandomProvider rng, int[] list)
> public static void shuffle(UniformRandomProvider rng,
> int[] list,
> int start,
> boolean towardHead)
>
> I would like to be able to shuffle other arrays such as double[].
> There is actually this functionality in [Lang] o.a.c.lang3.ArrayUtils.
> However it uses java.util.Random for the random source, and does not
> support a sub-range, e.g.
>
> public static void shuffle(final byte[] array)
> public static void shuffle(final byte[] array, final Random random)
>
> I suggest an API that requires UniformRandomProvider and can handle
> sub-ranges as:
>
> public static void shuffle(UniformRandomProvider rng, int[] data);
> public static void shuffle(UniformRandomProvider rng, int[] data, int
> from, int to);
> Or (similar to java.util.Arrays.copyOfRange):
> public static void shuffleOfRange(UniformRandomProvider rng, int[]
> data, int from, int to);
>
> This can be repeated for all 8 primitive types and generic type T.
>
> I suggest putting this in the sampling package but under what class?
> Note that all public class names in the sampling package currently end
> in Sampler. I would suggest ArraySampler.
>
> Note there is currently a ListSampler which has generic methods to
> return List<T> samples from a list, and shuffle lists. So adding
> ArraySampler with only shuffling would be missing equivalent sample
> methods. Consistency would require adding 8 variations of sample and a
> generic one:
>
> public static double[] sample(UniformRandomProvider rng,
> double[] array,
> int k) {
> public static <T> T[] sample(UniformRandomProvider rng,
> T[] array,
> int k)
>
> I have no use case for this but can add it for completeness.
>
> Alex
>
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