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#ifndef _VITERBI_H_
#define _VITERBI_H_
#include <vector>
#include "prob.h"
#include "hg.h"
#include "tdict.h"
std::string viterbi_stats(Hypergraph const& hg, std::string const& name="forest", bool estring=true, bool etree=false);
/// computes for each hg node the best (according to WeightType/WeightFunction) derivation, and some homomorphism (bottom up expression tree applied through Traversal) of it. T is the "return type" of Traversal, which is called only once for the best edge for a node's result (i.e. result will start default constructed)
//TODO: make T a typename inside Traversal and WeightType a typename inside WeightFunction?
// Traversal must implement:
// typedef T Result;
// void operator()(Hypergraph::Edge const& e,const vector<const Result*>& ants, Result* result) const;
// WeightFunction must implement:
// typedef prob_t Weight;
// Weight operator()(Hypergraph::Edge const& e) const;
template<typename Traversal,typename WeightFunction>
typename WeightFunction::Weight Viterbi(const Hypergraph& hg,
typename Traversal::Result* result,
const Traversal& traverse,
const WeightFunction& weight) {
typedef typename Traversal::Result T;
typedef typename WeightFunction::Weight WeightType;
const int num_nodes = hg.nodes_.size();
std::vector<T> vit_result(num_nodes);
std::vector<WeightType> vit_weight(num_nodes, WeightType::Zero());
for (int i = 0; i < num_nodes; ++i) {
const Hypergraph::Node& cur_node = hg.nodes_[i];
WeightType* const cur_node_best_weight = &vit_weight[i];
T* const cur_node_best_result = &vit_result[i];
const int num_in_edges = cur_node.in_edges_.size();
if (num_in_edges == 0) {
*cur_node_best_weight = WeightType(1);
continue;
}
Hypergraph::Edge const* edge_best=0;
for (int j = 0; j < num_in_edges; ++j) {
const Hypergraph::Edge& edge = hg.edges_[cur_node.in_edges_[j]];
WeightType score = weight(edge);
for (int k = 0; k < edge.tail_nodes_.size(); ++k)
score *= vit_weight[edge.tail_nodes_[k]];
if (!edge_best || *cur_node_best_weight < score) {
*cur_node_best_weight = score;
edge_best=&edge;
}
}
assert(edge_best);
Hypergraph::Edge const& edgeb=*edge_best;
std::vector<const T*> antsb(edgeb.tail_nodes_.size());
for (int k = 0; k < edgeb.tail_nodes_.size(); ++k)
antsb[k] = &vit_result[edgeb.tail_nodes_[k]];
traverse(edgeb, antsb, cur_node_best_result);
}
std::swap(*result, vit_result.back());
return vit_weight.back();
}
/*
template<typename Traversal,typename WeightFunction>
typename WeightFunction::Weight Viterbi(const Hypergraph& hg,
typename Traversal::Result* result)
{
Traversal traverse;
WeightFunction weight;
return Viterbi(hg,result,traverse,weight);
}
template<class Traversal,class WeightFunction=EdgeProb>
typename WeightFunction::Weight Viterbi(const Hypergraph& hg,
typename Traversal::Result* result,
Traversal const& traverse=Traversal()
)
{
WeightFunction weight;
return Viterbi(hg,result,traverse,weight);
}
*/
//spec for EdgeProb
template<class Traversal>
prob_t Viterbi(const Hypergraph& hg,
typename Traversal::Result* result,
Traversal const& traverse=Traversal()
)
{
EdgeProb weight;
return Viterbi(hg,result,traverse,weight);
}
struct PathLengthTraversal {
typedef int Result;
void operator()(const Hypergraph::Edge& edge,
const std::vector<const int*>& ants,
int* result) const {
(void) edge;
*result = 1;
for (int i = 0; i < ants.size(); ++i) *result += *ants[i];
}
};
struct ESentenceTraversal {
typedef std::vector<WordID> Result;
void operator()(const Hypergraph::Edge& edge,
const std::vector<const Result*>& ants,
Result* result) const {
edge.rule_->ESubstitute(ants, result);
}
};
struct ELengthTraversal {
typedef int Result;
void operator()(const Hypergraph::Edge& edge,
const std::vector<const int*>& ants,
int* result) const {
*result = edge.rule_->ELength() - edge.rule_->Arity();
for (int i = 0; i < ants.size(); ++i) *result += *ants[i];
}
};
struct FSentenceTraversal {
typedef std::vector<WordID> Result;
void operator()(const Hypergraph::Edge& edge,
const std::vector<const Result*>& ants,
Result* result) const {
edge.rule_->FSubstitute(ants, result);
}
};
// create a strings of the form (S (X the man) (X said (X he (X would (X go)))))
struct ETreeTraversal {
ETreeTraversal() : left("("), space(" "), right(")") {}
const std::string left;
const std::string space;
const std::string right;
typedef std::vector<WordID> Result;
void operator()(const Hypergraph::Edge& edge,
const std::vector<const Result*>& ants,
Result* result) const {
Result tmp;
edge.rule_->ESubstitute(ants, &tmp);
const std::string cat = TD::Convert(edge.rule_->GetLHS() * -1);
if (cat == "Goal")
result->swap(tmp);
else
TD::ConvertSentence(left + cat + space + TD::GetString(tmp) + right,
result);
}
};
struct FTreeTraversal {
FTreeTraversal() : left("("), space(" "), right(")") {}
const std::string left;
const std::string space;
const std::string right;
typedef std::vector<WordID> Result;
void operator()(const Hypergraph::Edge& edge,
const std::vector<const Result*>& ants,
Result* result) const {
Result tmp;
edge.rule_->FSubstitute(ants, &tmp);
const std::string cat = TD::Convert(edge.rule_->GetLHS() * -1);
if (cat == "Goal")
result->swap(tmp);
else
TD::ConvertSentence(left + cat + space + TD::GetString(tmp) + right,
result);
}
};
struct ViterbiPathTraversal {
typedef std::vector<Hypergraph::Edge const*> Result;
void operator()(const Hypergraph::Edge& edge,
std::vector<Result const*> const& ants,
Result* result) const {
for (int i = 0; i < ants.size(); ++i)
for (int j = 0; j < ants[i]->size(); ++j)
result->push_back((*ants[i])[j]);
result->push_back(&edge);
}
};
struct FeatureVectorTraversal {
typedef FeatureVector Result;
void operator()(Hypergraph::Edge const& edge,
std::vector<Result const*> const& ants,
Result* result) const {
for (int i = 0; i < ants.size(); ++i)
*result+=*ants[i];
*result+=edge.feature_values_;
}
};
std::string JoshuaVisualizationString(const Hypergraph& hg);
prob_t ViterbiESentence(const Hypergraph& hg, std::vector<WordID>* result);
std::string ViterbiETree(const Hypergraph& hg);
prob_t ViterbiFSentence(const Hypergraph& hg, std::vector<WordID>* result);
std::string ViterbiFTree(const Hypergraph& hg);
int ViterbiELength(const Hypergraph& hg);
int ViterbiPathLength(const Hypergraph& hg);
/// if weights supplied, assert viterbi prob = features.dot(*weights). return features (sum over all edges in viterbi derivation)
FeatureVector ViterbiFeatures(Hypergraph const& hg,FeatureWeights const* weights=0);
#endif
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