void InferenceEngineBP::computeBeliefs(Beliefs &beliefs, FeatureGenerator *fGen,
DataSequence *X, Model *m, int bComputePartition, int seqLabel, bool bUseStatePerNodes)
{
// Variable definition
int xi, xj, nbNodes, seqLength;
std::map<int,BPNode*> nodes; // tree graph
std::map<int,BPNode*>::iterator itm;
std::list<BPNode*>::iterator itl;
BPNode* root;
iMatrix adjMat;
iVector nbStates;
dVector* phi_i = 0; // singleton potentials
dMatrix** phi_ij = 0; // pairwise potentials
dVector** msg = 0; // messages
if( m->isMultiViewMode() )
m->getAdjacencyMatrixMV(adjMat, X);
else {
uMatrix uAdjMat;
m->getAdjacencyMatrix(uAdjMat, X);
adjMat.resize(uAdjMat.getWidth(),uAdjMat.getHeight());
for(xi=0; xi<uAdjMat.getHeight(); xi++)
for(xj=0; xj<uAdjMat.getWidth(); xj++)
adjMat(xi,xj) = uAdjMat(xi,xj);
}
nbNodes = adjMat.getHeight();
seqLength = X->length();
// Create a vector that contains nbStates
nbStates.create(nbNodes);
for(xi=0; xi<nbNodes; xi++)
nbStates[xi] = (m->isMultiViewMode())
? m->getNumberOfStatesMV(xi/seqLength) : m->getNumberOfStates();
// Create BPGraph from adjMat
for(xi=0; xi<nbNodes; xi++) {
BPNode* v = new BPNode(xi, nbStates[xi]);
nodes.insert( std::pair<int,BPNode*>(xi,v) );
}
for(xi=0; xi<nbNodes; xi++) {
for(xj=xi+1; xj<nbNodes; xj++) {
if( !adjMat(xi,xj) ) continue;
nodes[xi]->addNeighbor(nodes[xj]);
nodes[xj]->addNeighbor(nodes[xi]);
}
}
// Initialize
initMessages(msg, X, m, adjMat, nbStates);
initBeliefs(beliefs, X, m, adjMat, nbStates);
initPotentials(phi_i, phi_ij, fGen, X, m, adjMat, nbStates, seqLabel);
// Message update
root = nodes[0]; // any node can be the root node
{
for(itl=root->neighbors.begin(); itl!=root->neighbors.end(); itl++)
collect(root, *itl, phi_i, phi_ij, msg);
for(itl=root->neighbors.begin(); itl!=root->neighbors.end(); itl++)
distribute(root, *itl, phi_i, phi_ij, msg);
}
updateBeliefs(beliefs, phi_i, phi_ij, msg, X, m, adjMat);
// Clean up
for(xi=0; xi<nbNodes; xi++) {
delete[] msg[xi]; msg[xi] = 0;
delete[] phi_ij[xi]; phi_ij[xi] = 0;
}
delete[] msg; msg=0;
delete[] phi_i; phi_i = 0;
delete[] phi_ij; phi_ij = 0;
for(itm=nodes.begin(); itm!=nodes.end(); itm++)
delete (*itm).second;
nodes.clear();
}
void InferenceEngineLoopyBP::computeBeliefs(Beliefs &beliefs, FeatureGenerator *fGen,
DataSequence *X, Model *m, int bComputePartition, int seqLabel, bool bUseStatePerNodes)
{
// Get adjacency matrix; values indicate edge index (use upper triangle only)
iMatrix adjMat;
if( m->isMultiViewMode() )
m->getAdjacencyMatrixMV(adjMat, X);
else {
// Quick and dirty, but I don't want to change Model::makeChain()
int edgeID = 1;
adjMat.create(X->length(),X->length());
for(int r=1; r<adjMat.getHeight(); r++) {
adjMat(r,r-1) = edgeID;
adjMat(r-1,r) = edgeID;
edgeID++;
}
}
int adjMatMax = adjMat.getMaxValue();
// 1. Initialize beliefs
initializeBeliefs(beliefs, X, m, adjMat);
// 2. Initialize messages
std::vector<dVector> messages, prev_messages;
initializeMessages(messages, X, m, adjMat, adjMatMax, false);
for(unsigned int i=0; i<messages.size(); i++) {
dVector v; prev_messages.push_back(v);
}
// 3. Initialize potentials
Beliefs potentials;
initializePotentials(potentials, fGen, X, m, adjMat, seqLabel, bUseStatePerNodes);
// 4. Update loopy belief network
int T = X->length();
int V = m->getNumberOfViews();
int nbNodes = V*T;
int *messageUpdateOrder = new int[nbNodes];
for(int iter=0; iter<m_max_iter; iter++)
{
// Get message update order
getRandomUpdateOrder(messageUpdateOrder, X, m);
// Update messages
for( int i=0; i<nbNodes; i++ ) {
int xi = messageUpdateOrder[i];
for( int xj=0; xj<nbNodes; xj++ ) {
if( !adjMat(xi,xj) ) continue;
sendMessage(xi,xj,nbNodes,potentials,messages,adjMat,adjMatMax,m->isMaxMargin());
}
}
// Convergence check
if( iter>0 ) {
double error = 0;
for(unsigned int i=0; i<messages.size(); i++)
for(int j=0; j<messages[i].getLength(); j++)
error += fabs(messages[i][j] - prev_messages[i][j]);
if( error < m_min_threshold ) break;
}
// Copy messages
for(unsigned int i=0; i<messages.size(); i++)
prev_messages[i] = messages[i];
}
// Compute beliefs & compute partition
updateBeliefs(nbNodes, beliefs, potentials, messages, adjMat, adjMatMax);
// 5. Clean up and Return
if( messageUpdateOrder ) {
delete[] messageUpdateOrder; messageUpdateOrder = 0;
}
}
