[1d7c18]: src / modules / glm / samplers / IWLS.cc  Maximize  Restore  History

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#include <config.h>
#include "IWLS.h"
#include <graph/LinkNode.h>
#include <graph/StochasticNode.h>
//#include <function/LinkFunction.h>
#include <distribution/Distribution.h>
#include <rng/RNG.h>
#include <module/ModuleError.h>
#include <cmath>
extern "C" {
#include <cholmod.h>
}
extern cholmod_common *glm_wk;
using std::string;
using std::vector;
using std::exp;
using std::fabs;
using std::log;
static unsigned int nchildren(GraphView const *view)
{
return view->stochasticChildren().size();
}
static double logDet(cholmod_factor *F)
{
if (!F->is_ll && !F->is_monotonic) {
throwLogicError("Non-monotonic simplicial factor in logDet");
}
int *Fp = static_cast<int*>(F->p);
double *Fx = static_cast<double*>(F->x);
double y = 0;
for (unsigned int r = 0; r < F->n; ++r) {
y += log(Fx[Fp[r]]);
}
return F->is_ll ? 2*y : y;
}
#define MAX_ITER 100
#define ANNEALING_TEMPERATURE 20
namespace glm {
IWLS::IWLS(GraphView const *view,
vector<GraphView const *> const &sub_views,
unsigned int chain)
: GLMMethod(view, sub_views, chain, true),
_link(nchildren(view)), _family(nchildren(view)),
_init(true), _w(0)
{
vector<StochasticNode const*> const &children =
view->stochasticChildren();
for (unsigned int i = 0; i < children.size(); ++i) {
_link[i] = dynamic_cast<LinkNode const*>(children[i]->parents()[0]);
_family[i] = getFamily(children[i]);
}
}
string IWLS::name() const
{
return "IWLS";
}
double IWLS::getPrecision(unsigned int i) const
{
double w = _w;
if (_family[i] == GLM_BINOMIAL) {
Node const *size = _view->stochasticChildren()[i]->parents()[1];
w *= size->value(_chain)[0];
}
double grad = _link[i]->grad(_chain);
return (w * grad * grad)/ var(i);
}
double IWLS::getValue(unsigned int i) const
{
Node const *child = _view->stochasticChildren()[i];
double y = child->value(_chain)[0];
if (_family[i] == GLM_BINOMIAL) {
double N = child->parents()[1]->value(_chain)[0];
y /= N;
}
double mu = _link[i]->value(_chain)[0];
double eta = _link[i]->eta(_chain);
double grad = _link[i]->grad(_chain);
return eta + (y - mu) / grad;
}
double IWLS::var(unsigned int i) const
{
double mu = _link[i]->value(_chain)[0];
switch(_family[i]) {
case GLM_BERNOULLI: case GLM_BINOMIAL:
return mu * (1 - mu);
break;
case GLM_POISSON:
return mu;
break;
case GLM_NORMAL:
return 1;
break;
case GLM_UNKNOWN:
throwLogicError("Unknown GLM family in IWLS");
}
return 0; //-Wall
}
double IWLS::logPTransition(vector<double> const &xorig,
vector<double> const &x,
double *b, cholmod_sparse *A)
{
unsigned int n = _view->length();
//Difference between new and old values
cholmod_dense *delta = cholmod_allocate_dense(n, 1, n, CHOLMOD_REAL,
glm_wk);
double *dx = static_cast<double*>(delta->x);
for (unsigned int i = 0; i < n; ++i) {
dx[i] = x[i] - xorig[i];
}
int ok = cholmod_factorize(A, _factor, glm_wk);
if (!ok) {
throwRuntimeError("Cholesky decomposition failure in IWLS");
}
//Posterior mean
cholmod_dense *mu = cholmod_solve(CHOLMOD_A, _factor, delta, glm_wk);
double *mux = static_cast<double*>(mu->x);
//Setup pointers to sparse matrix A
int *Ap = static_cast<int*>(A->p);
int *Ai = static_cast<int*>(A->i);
double *Ax = static_cast<double*>(A->x);
double deviance = 0;
for (unsigned int r = 0; r < n; ++r) {
double Adr = 0;
for (int j = Ap[r]; j < Ap[r+1]; ++j) {
Adr += Ax[j] * dx[Ai[j]];
}
deviance += dx[r] * (Adr - 2 * b[r]) + b[r] * mux[r];
}
deviance -= logDet(_factor);
cholmod_free_dense(&delta, glm_wk);
cholmod_free_dense(&mu, glm_wk);
return -deviance/2;
}
void IWLS::update(RNG *rng)
{
if (_init) {
_w = 0;
for (unsigned int i = 0; i < MAX_ITER; ++i) {
_w += 1.0/MAX_ITER;
updateLM(rng, ANNEALING_TEMPERATURE);
}
_init = false;
}
double *b1, *b2;
cholmod_sparse *A1, *A2;
double logp = 0;
vector<double> xold(_view->length());
_view->getValue(xold, _chain);
calCoef(b1, A1);
logp -= _view->logFullConditional(_chain);
updateLM(rng);
logp += _view->logFullConditional(_chain);
vector<double> xnew(_view->length());
_view->getValue(xnew, _chain);
calCoef(b2, A2);
logp -= logPTransition(xold, xnew, b1, A1);
logp += logPTransition(xnew, xold, b2, A2);
cholmod_free_sparse(&A1, glm_wk);
cholmod_free_sparse(&A2, glm_wk);
delete [] b1; delete [] b2;
//Acceptance step
if (rng->uniform() > exp(logp)) {
_view->setValue(xold, _chain);
}
}
}

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