diff options
Diffstat (limited to 'vest/viterbi_envelope.cc')
| -rw-r--r-- | vest/viterbi_envelope.cc | 167 |
1 files changed, 167 insertions, 0 deletions
diff --git a/vest/viterbi_envelope.cc b/vest/viterbi_envelope.cc new file mode 100644 index 00000000..1122030a --- /dev/null +++ b/vest/viterbi_envelope.cc @@ -0,0 +1,167 @@ +#include "viterbi_envelope.h" + +#include <cassert> +#include <limits> + +using namespace std; +using boost::shared_ptr; + +ostream& operator<<(ostream& os, const ViterbiEnvelope& env) { + os << '<'; + const vector<shared_ptr<Segment> >& segs = env.GetSortedSegs(); + for (int i = 0; i < segs.size(); ++i) + os << (i==0 ? "" : "|") << "x=" << segs[i]->x << ",b=" << segs[i]->b << ",m=" << segs[i]->m << ",p1=" << segs[i]->p1 << ",p2=" << segs[i]->p2; + return os << '>'; +} + +ViterbiEnvelope::ViterbiEnvelope(int i) { + if (i == 0) { + // do nothing - <> + } else if (i == 1) { + segs.push_back(shared_ptr<Segment>(new Segment(0, 0, 0, shared_ptr<Segment>(), shared_ptr<Segment>()))); + assert(this->IsMultiplicativeIdentity()); + } else { + cerr << "Only can create ViterbiEnvelope semiring 0 and 1 with this constructor!\n"; + abort(); + } +} + +struct SlopeCompare { + bool operator() (const shared_ptr<Segment>& a, const shared_ptr<Segment>& b) const { + return a->m < b->m; + } +}; + +const ViterbiEnvelope& ViterbiEnvelope::operator+=(const ViterbiEnvelope& other) { + if (!other.is_sorted) other.Sort(); + if (segs.empty()) { + segs = other.segs; + return *this; + } + is_sorted = false; + int j = segs.size(); + segs.resize(segs.size() + other.segs.size()); + for (int i = 0; i < other.segs.size(); ++i) + segs[j++] = other.segs[i]; + assert(j == segs.size()); + return *this; +} + +void ViterbiEnvelope::Sort() const { + sort(segs.begin(), segs.end(), SlopeCompare()); + const int k = segs.size(); + int j = 0; + for (int i = 0; i < k; ++i) { + Segment l = *segs[i]; + l.x = kMinusInfinity; + // cerr << "m=" << l.m << endl; + if (0 < j) { + if (segs[j-1]->m == l.m) { // lines are parallel + if (l.b <= segs[j-1]->b) continue; + --j; + } + while(0 < j) { + l.x = (l.b - segs[j-1]->b) / (segs[j-1]->m - l.m); + if (segs[j-1]->x < l.x) break; + --j; + } + if (0 == j) l.x = kMinusInfinity; + } + *segs[j++] = l; + } + segs.resize(j); + is_sorted = true; +} + +const ViterbiEnvelope& ViterbiEnvelope::operator*=(const ViterbiEnvelope& other) { + if (other.IsMultiplicativeIdentity()) { return *this; } + if (this->IsMultiplicativeIdentity()) { (*this) = other; return *this; } + + if (!is_sorted) Sort(); + if (!other.is_sorted) other.Sort(); + + if (this->IsEdgeEnvelope()) { +// if (other.size() > 1) +// cerr << *this << " (TIMES) " << other << endl; + shared_ptr<Segment> edge_parent = segs[0]; + const double& edge_b = edge_parent->b; + const double& edge_m = edge_parent->m; + segs.clear(); + for (int i = 0; i < other.segs.size(); ++i) { + const Segment& seg = *other.segs[i]; + const double m = seg.m + edge_m; + const double b = seg.b + edge_b; + const double& x = seg.x; // x's don't change with * + segs.push_back(shared_ptr<Segment>(new Segment(x, m, b, edge_parent, other.segs[i]))); + assert(segs.back()->p1->rule); + } +// if (other.size() > 1) +// cerr << " = " << *this << endl; + } else { + vector<shared_ptr<Segment> > new_segs; + int this_i = 0; + int other_i = 0; + const int this_size = segs.size(); + const int other_size = other.segs.size(); + double cur_x = kMinusInfinity; // moves from left to right across the + // real numbers, stopping for all inter- + // sections + double this_next_val = (1 < this_size ? segs[1]->x : kPlusInfinity); + double other_next_val = (1 < other_size ? other.segs[1]->x : kPlusInfinity); + while (this_i < this_size && other_i < other_size) { + const Segment& this_seg = *segs[this_i]; + const Segment& other_seg= *other.segs[other_i]; + const double m = this_seg.m + other_seg.m; + const double b = this_seg.b + other_seg.b; + + new_segs.push_back(shared_ptr<Segment>(new Segment(cur_x, m, b, segs[this_i], other.segs[other_i]))); + int comp = 0; + if (this_next_val < other_next_val) comp = -1; else + if (this_next_val > other_next_val) comp = 1; + if (0 == comp) { // the next values are equal, advance both indices + ++this_i; + ++other_i; + cur_x = this_next_val; // could be other_next_val (they're equal!) + this_next_val = (this_i+1 < this_size ? segs[this_i+1]->x : kPlusInfinity); + other_next_val = (other_i+1 < other_size ? other.segs[other_i+1]->x : kPlusInfinity); + } else { // advance the i with the lower x, update cur_x + if (-1 == comp) { + ++this_i; + cur_x = this_next_val; + this_next_val = (this_i+1 < this_size ? segs[this_i+1]->x : kPlusInfinity); + } else { + ++other_i; + cur_x = other_next_val; + other_next_val = (other_i+1 < other_size ? other.segs[other_i+1]->x : kPlusInfinity); + } + } + } + segs.swap(new_segs); + } + //cerr << "Multiply: result=" << (*this) << endl; + return *this; +} + +// recursively construct translation +void Segment::ConstructTranslation(vector<WordID>* trans) const { + const Segment* cur = this; + vector<vector<WordID> > ant_trans; + while(!cur->rule) { + ant_trans.resize(ant_trans.size() + 1); + cur->p2->ConstructTranslation(&ant_trans.back()); + cur = cur->p1.get(); + } + size_t ant_size = ant_trans.size(); + vector<const vector<WordID>*> pants(ant_size); + --ant_size; + for (int i = 0; i < pants.size(); ++i) pants[ant_size - i] = &ant_trans[i]; + cur->rule->ESubstitute(pants, trans); +} + +ViterbiEnvelope ViterbiEnvelopeWeightFunction::operator()(const Hypergraph::Edge& e) const { + const double m = direction.dot(e.feature_values_); + const double b = origin.dot(e.feature_values_); + Segment* seg = new Segment(m, b, e.rule_); + return ViterbiEnvelope(1, seg); +} + |