From 1b8181bf0d6e9137e6b9ccdbe414aec37377a1a9 Mon Sep 17 00:00:00 2001
From: Chris Dyer <cdyer@allegro.clab.cs.cmu.edu>
Date: Sun, 18 Nov 2012 13:35:42 -0500
Subject: major restructure of the training code

---
 training/dtrain/kbestget.h | 152 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 152 insertions(+)
 create mode 100644 training/dtrain/kbestget.h

(limited to 'training/dtrain/kbestget.h')

diff --git a/training/dtrain/kbestget.h b/training/dtrain/kbestget.h
new file mode 100644
index 00000000..dd8882e1
--- /dev/null
+++ b/training/dtrain/kbestget.h
@@ -0,0 +1,152 @@
+#ifndef _DTRAIN_KBESTGET_H_
+#define _DTRAIN_KBESTGET_H_
+
+#include "kbest.h" // cdec
+#include "sentence_metadata.h"
+
+#include "verbose.h"
+#include "viterbi.h"
+#include "ff_register.h"
+#include "decoder.h"
+#include "weights.h"
+#include "logval.h"
+
+using namespace std;
+
+namespace dtrain
+{
+
+
+typedef double score_t;
+
+struct ScoredHyp
+{
+  vector<WordID> w;
+  SparseVector<double> f;
+  score_t model;
+  score_t score;
+  unsigned rank;
+};
+
+struct LocalScorer
+{
+  unsigned N_;
+  vector<score_t> w_;
+
+  virtual score_t
+  Score(vector<WordID>& hyp, vector<WordID>& ref, const unsigned rank, const unsigned src_len)=0;
+
+  void Reset() {} // only for approx bleu
+
+  inline void
+  Init(unsigned N, vector<score_t> weights)
+  {
+    assert(N > 0);
+    N_ = N;
+    if (weights.empty()) for (unsigned i = 0; i < N_; i++) w_.push_back(1./N_);
+    else w_ = weights;
+  }
+
+  inline score_t
+  brevity_penalty(const unsigned hyp_len, const unsigned ref_len)
+  {
+    if (hyp_len > ref_len) return 1;
+    return exp(1 - (score_t)ref_len/hyp_len);
+  }
+};
+
+struct HypSampler : public DecoderObserver
+{
+  LocalScorer* scorer_;
+  vector<WordID>* ref_;
+  unsigned f_count_, sz_;
+  virtual vector<ScoredHyp>* GetSamples()=0;
+  inline void SetScorer(LocalScorer* scorer) { scorer_ = scorer; }
+  inline void SetRef(vector<WordID>& ref) { ref_ = &ref; }
+  inline unsigned get_f_count() { return f_count_; }
+  inline unsigned get_sz() { return sz_; }
+};
+////////////////////////////////////////////////////////////////////////////////
+
+
+
+
+struct KBestGetter : public HypSampler
+{
+  const unsigned k_;
+  const string filter_type_;
+  vector<ScoredHyp> s_;
+  unsigned src_len_;
+
+  KBestGetter(const unsigned k, const string filter_type) :
+    k_(k), filter_type_(filter_type) {}
+
+  virtual void
+  NotifyTranslationForest(const SentenceMetadata& smeta, Hypergraph* hg)
+  {
+    src_len_ = smeta.GetSourceLength();
+    KBestScored(*hg);
+  }
+
+  vector<ScoredHyp>* GetSamples() { return &s_; }
+
+  void
+  KBestScored(const Hypergraph& forest)
+  {
+    if (filter_type_ == "uniq") {
+      KBestUnique(forest);
+    } else if (filter_type_ == "not") {
+      KBestNoFilter(forest);
+    }
+  }
+
+  void
+  KBestUnique(const Hypergraph& forest)
+  {
+    s_.clear(); sz_ = f_count_ = 0;
+    KBest::KBestDerivations<vector<WordID>, ESentenceTraversal,
+      KBest::FilterUnique, prob_t, EdgeProb> kbest(forest, k_);
+    for (unsigned i = 0; i < k_; ++i) {
+      const KBest::KBestDerivations<vector<WordID>, ESentenceTraversal, KBest::FilterUnique,
+              prob_t, EdgeProb>::Derivation* d =
+            kbest.LazyKthBest(forest.nodes_.size() - 1, i);
+      if (!d) break;
+      ScoredHyp h;
+      h.w = d->yield;
+      h.f = d->feature_values;
+      h.model = log(d->score);
+      h.rank = i;
+      h.score = scorer_->Score(h.w, *ref_, i, src_len_);
+      s_.push_back(h);
+      sz_++;
+      f_count_ += h.f.size();
+    }
+  }
+
+  void
+  KBestNoFilter(const Hypergraph& forest)
+  {
+    s_.clear(); sz_ = f_count_ = 0;
+    KBest::KBestDerivations<vector<WordID>, ESentenceTraversal> kbest(forest, k_);
+    for (unsigned i = 0; i < k_; ++i) {
+      const KBest::KBestDerivations<vector<WordID>, ESentenceTraversal>::Derivation* d =
+            kbest.LazyKthBest(forest.nodes_.size() - 1, i);
+      if (!d) break;
+      ScoredHyp h;
+      h.w = d->yield;
+      h.f = d->feature_values;
+      h.model = log(d->score);
+      h.rank = i;
+      h.score = scorer_->Score(h.w, *ref_, i, src_len_);
+      s_.push_back(h);
+      sz_++;
+      f_count_ += h.f.size();
+    }
+  }
+};
+
+
+} // namespace
+
+#endif
+
-- 
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