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extern crate rand;
use self::rand::Rng;
use data::DataOrSuffStat;
use std::fmt::Debug;
use std::marker::PhantomData;
use std::sync::Arc;
use traits::*;
pub struct ConjugateModel<X, Fx, Pr>
where
X: Debug,
Fx: Rv<X> + HasSuffStat<X>,
Pr: ConjugatePrior<X, Fx>,
{
prior: Arc<Pr>,
suffstat: Fx::Stat,
_phantom: PhantomData<X>,
}
impl<X, Fx, Pr> ConjugateModel<X, Fx, Pr>
where
X: Debug,
Fx: Rv<X> + HasSuffStat<X>,
Pr: ConjugatePrior<X, Fx>,
{
pub fn new(fx: &Fx, pr: Arc<Pr>) -> Self {
ConjugateModel {
prior: pr,
suffstat: fx.empty_suffstat(),
_phantom: PhantomData,
}
}
pub fn ln_m(&self) -> f64 {
self.prior.ln_m(&self.obs())
}
pub fn ln_pp(&self, y: &X) -> f64 {
self.prior.ln_pp(&y, &self.obs())
}
pub fn posterior(&self) -> Pr::Posterior {
self.prior.posterior(&self.obs())
}
fn obs(&self) -> DataOrSuffStat<X, Fx> {
DataOrSuffStat::SuffStat(&self.suffstat)
}
}
impl<X, Fx, Pr> SuffStat<X> for ConjugateModel<X, Fx, Pr>
where
X: Debug,
Fx: Rv<X> + HasSuffStat<X>,
Pr: ConjugatePrior<X, Fx>,
{
fn n(&self) -> usize {
self.suffstat.n()
}
fn observe(&mut self, x: &X) {
self.suffstat.observe(&x);
}
fn forget(&mut self, x: &X) {
self.suffstat.forget(&x);
}
}
impl<X, Fx, Pr> Rv<X> for ConjugateModel<X, Fx, Pr>
where
X: Debug,
Fx: Rv<X> + HasSuffStat<X>,
Pr: ConjugatePrior<X, Fx>,
{
fn ln_f(&self, x: &X) -> f64 {
self.prior.ln_pp(&x, &self.obs())
}
fn draw<R: Rng>(&self, mut rng: &mut R) -> X {
let post = self.posterior();
let fx: Fx = post.draw(&mut rng);
fx.draw(&mut rng)
}
fn sample<R: Rng>(&self, n: usize, mut rng: &mut R) -> Vec<X> {
let post = self.posterior();
(0..n)
.map(|_| {
let fx: Fx = post.draw(&mut rng);
fx.draw(&mut rng)
}).collect()
}
}