On Sat, 15 May 2021 at 16:02, Gilles Sadowski <[email protected]> wrote:
> Hi Alex.
>
> Would the proposal be any different if with Java 8+ features?
> [IOW, is it still useful (in any sense) to stick with Java 6?]
>
The Sampler<T> interface can be replaced with Supplier<T>. But then all the
sampling methods would have to be renamed to 'get()' as opposed to
'sample()' which we currently have in the codebase.
The interface BiFunction<T, U, R> can be used to specify the factory to
build the discrete sampler:
BiFunction<double[], UniformRandomProvider, DiscreteSampler>
I do not think any other Java 8 features would help reduce the new amount
of public API.
With Java 8 you could build a composite with streams. We would provide
access to the pair used to stored the sampler and the weights:
static class WeightedSampler<S> {
/** The weight. */
private final double weight;
/** The sampler. */
private final S sampler;
// etc...
}
You can then use streams to build a composite sampler from a source of
objects:
List<Triangle> triangles = ...;
UniformRandomProvider rng = ...;
ObjectSampler<double[]> surface = triangles.stream().map(t -> {
double area = t.getArea();
double[] a = t.getVertex(0);
double[] b = t.getVertex(1);
double[] c = t.getVertex(2);
return WeightedSample.of(area, TriangleSampler.of(a, b, c, rng));
}).collect(CompositeCollectors.toObjectSampler(rng));
double[] point = surface.sample();
The CompositeCollectors would amass the WeightedSamplers and construct the
composite. The class would still require 6 ways of calling it so that the 6
composite variants can be created.
This is just an idea. I do not think Java 8 is really a benefit and can be
added later.
Alex
