summaryrefslogtreecommitdiff
path: root/vest/viterbi_envelope.h
diff options
context:
space:
mode:
authorChris Dyer <redpony@gmail.com>2009-12-03 16:49:30 -0500
committerChris Dyer <redpony@gmail.com>2009-12-03 16:49:30 -0500
commit9fae7b75c64f4dfb6e45ff8f2ec61b597f37d225 (patch)
tree61a187c4fa6db8527f90f3060d18357f7b60b44a /vest/viterbi_envelope.h
parent671c21451542e2dd20e45b4033d44d8e8735f87b (diff)
fix build in new layout
Diffstat (limited to 'vest/viterbi_envelope.h')
-rw-r--r--vest/viterbi_envelope.h79
1 files changed, 79 insertions, 0 deletions
diff --git a/vest/viterbi_envelope.h b/vest/viterbi_envelope.h
new file mode 100644
index 00000000..39d2b537
--- /dev/null
+++ b/vest/viterbi_envelope.h
@@ -0,0 +1,79 @@
+#ifndef _VITERBI_ENVELOPE_H_
+#define _VITERBI_ENVELOPE_H_
+
+#include <vector>
+#include <iostream>
+#include <boost/shared_ptr.hpp>
+
+#include "hg.h"
+#include "sparse_vector.h"
+
+static const double kMinusInfinity = -std::numeric_limits<double>::infinity();
+static const double kPlusInfinity = std::numeric_limits<double>::infinity();
+
+struct Segment {
+ Segment() : x(), m(), b() {}
+ Segment(double _m, double _b) :
+ x(kMinusInfinity), m(_m), b(_b) {}
+ Segment(double _x, double _m, double _b, const boost::shared_ptr<Segment>& p1_, const boost::shared_ptr<Segment>& p2_) :
+ x(_x), m(_m), b(_b), p1(p1_), p2(p2_) {}
+ Segment(double _m, double _b, TRulePtr _rule) :
+ x(kMinusInfinity), m(_m), b(_b), rule(_rule) {}
+
+ double x; // x intersection with previous segment in env, or -inf if none
+ double m; // this line's slope
+ double b; // intercept with y-axis
+
+ // we keep a pointer to the "parents" of this segment so we can reconstruct
+ // the Viterbi translation corresponding to this segment
+ boost::shared_ptr<Segment> p1;
+ boost::shared_ptr<Segment> p2;
+
+ // only Segments created from an edge using the ViterbiEnvelopeWeightFunction
+ // have rules
+ TRulePtr rule;
+
+ // recursively recover the Viterbi translation that will result from setting
+ // the weights to origin + axis * x, where x is any value from this->x up
+ // until the next largest x in the containing ViterbiEnvelope
+ void ConstructTranslation(std::vector<WordID>* trans) const;
+};
+
+// this is the semiring value type,
+// it defines constructors for 0, 1, and the operations + and *
+struct ViterbiEnvelope {
+ // create semiring zero
+ ViterbiEnvelope() : is_sorted(true) {} // zero
+ // for debugging:
+ ViterbiEnvelope(const std::vector<boost::shared_ptr<Segment> >& s) : segs(s) { Sort(); }
+ // create semiring 1 or 0
+ explicit ViterbiEnvelope(int i);
+ ViterbiEnvelope(int n, Segment* seg) : is_sorted(true), segs(n, boost::shared_ptr<Segment>(seg)) {}
+ const ViterbiEnvelope& operator+=(const ViterbiEnvelope& other);
+ const ViterbiEnvelope& operator*=(const ViterbiEnvelope& other);
+ bool IsMultiplicativeIdentity() const {
+ return size() == 1 && (segs[0]->b == 0.0 && segs[0]->m == 0.0) && (!segs[0]->rule); }
+ const std::vector<boost::shared_ptr<Segment> >& GetSortedSegs() const {
+ if (!is_sorted) Sort();
+ return segs;
+ }
+ size_t size() const { return segs.size(); }
+
+ private:
+ bool IsEdgeEnvelope() const {
+ return segs.size() == 1 && segs[0]->rule; }
+ void Sort() const;
+ mutable bool is_sorted;
+ mutable std::vector<boost::shared_ptr<Segment> > segs;
+};
+std::ostream& operator<<(std::ostream& os, const ViterbiEnvelope& env);
+
+struct ViterbiEnvelopeWeightFunction {
+ ViterbiEnvelopeWeightFunction(const SparseVector<double>& ori,
+ const SparseVector<double>& dir) : origin(ori), direction(dir) {}
+ ViterbiEnvelope operator()(const Hypergraph::Edge& e) const;
+ const SparseVector<double> origin;
+ const SparseVector<double> direction;
+};
+
+#endif