On Mon, Oct 31, 2011 at 2:56 PM, cwinter <chwinterho...@aol.com> wrote:
> > Phil Steitz wrote: > > > > Maybe it would be best to eliminate IntegerDistribution then and > > merge Distribution and ContinuousDistribution, so we have two roots > > - DiscreteDistribution and ContinuousDistribution. The only reason > > really to have DiscreteDistribution is if we want to support > > distributions of RVs over sample spaces that are not subsets of Z. > > There does not seem to be much enthusiasm for that (i.e. > > parameterizing the type of the domain of the distribution and pmf), > > so we might as well just collapse Discrete and Integer. Once you > > pull out Discrete/Integer, there is not much value any more in > > Distribution as a parent, so why not just drop both > > IntegerDistribution and Distribution and move to two roots with > > doubles / ints as domains and contracts cleaned up to deal with > > discrete vs continuous cases consistently. > > > > Phil > > > > I'm absolutely convinced that the approach with two roots suits our needs. > However, for real-valued random variables we need a hierarchy of > distribution interfaces because not every distribution on the reals has a > density. Lordy... this is really more complicated than necessary. You could just have a single interface/abstract class and have distributions throw UOE if they can't do something like give you a density. At most, a marker interface or hasDensity() indicator method is needed. Commons projects and commons math really have a tendency to over-engineer the type structure instead of just going and implementing some useful functions. > Thus I'd like to keep Distribution and ContinuousDistribution. But > maybe we could change the names to put more emphasis on the domain of > the distribution, e.g. to RealDistribution and ContinuousRealDistribution. > Do you have any code for which this distinction would actually matter more than a hairs-breadth? > ... Apart from this, a separate interface for more general discrete > distributions is indeed not required. > I should bless you for saying this at least.
