cool new alignment feature

4 files changed, 91 insertions, 3 deletions

diff --git a/decoder/cdec_ff.cc b/decoder/cdec_ff.cc
index bb2c9d34..437de428 100644
--- a/decoder/cdec_ff.cc
+++ b/decoder/cdec_ff.cc
@@ -15,6 +15,7 @@ void register_feature_functions() {
   global_ff_registry->Register("SourceWordPenalty", new FFFactory<SourceWordPenalty>);
   global_ff_registry->Register("RelativeSentencePosition", new FFFactory<RelativeSentencePosition>);
   global_ff_registry->Register("MarkovJump", new FFFactory<MarkovJump>);
+  global_ff_registry->Register("SourcePOSBigram", new FFFactory<SourcePOSBigram>);
   global_ff_registry->Register("BlunsomSynchronousParseHack", new FFFactory<BlunsomSynchronousParseHack>);
   global_ff_registry->Register("AlignerResults", new FFFactory<AlignerResults>);
   global_ff_registry->Register("CSplit_BasicFeatures", new FFFactory<BasicCSplitFeatures>);
diff --git a/decoder/ff_wordalign.cc b/decoder/ff_wordalign.cc
index a00b2c76..f07eda02 100644
--- a/decoder/ff_wordalign.cc
+++ b/decoder/ff_wordalign.cc
@@ -1,5 +1,6 @@
 #include "ff_wordalign.h"
 
+#include <sstream>
 #include <string>
 #include <cmath>
 
@@ -126,6 +127,72 @@ void MarkovJump::TraversalFeaturesImpl(const SentenceMetadata& smeta,
   }
 }
 
+// state: POS of src word used, number of trg words generated
+SourcePOSBigram::SourcePOSBigram(const std::string& param) :
+    FeatureFunction(sizeof(WordID) + sizeof(int)) {
+  cerr << "Reading source POS tags from " << param << endl;
+  ReadFile rf(param);
+  istream& in = *rf.stream();
+  while(in) {
+    string line;
+    getline(in, line);
+    if (line.empty()) continue;
+    vector<WordID> v;
+    TD::ConvertSentence(line, &v);
+    pos_.push_back(v);
+  }
+  cerr << "  (" << pos_.size() << " lines)\n";
+}
+
+void SourcePOSBigram::FireFeature(WordID left,
+                   WordID right,
+                   SparseVector<double>* features) const {
+  int& fid = fmap_[left][right];
+  if (!fid) {
+    ostringstream os;
+    os << "SP:";
+    if (left < 0) { os << "BOS"; } else { os << TD::Convert(left); }
+    os << '_';
+    if (right < 0) { os << "EOS"; } else { os << TD::Convert(right); }
+    fid = FD::Convert(os.str());
+    if (fid == 0) fid = -1;
+  }
+  if (fid < 0) return;
+  features->set_value(fid, 1.0);
+}
+
+void SourcePOSBigram::TraversalFeaturesImpl(const SentenceMetadata& smeta,
+                                     const Hypergraph::Edge& edge,
+                                     const std::vector<const void*>& ant_contexts,
+                                     SparseVector<double>* features,
+                                     SparseVector<double>* estimated_features,
+                                     void* context) const {
+  WordID& out_context = *static_cast<WordID*>(context);
+  int& out_word_count = *(static_cast<int*>(context) + 1);
+  const int arity = edge.Arity();
+  if (arity == 0) {
+    assert(smeta.GetSentenceID() < pos_.size());
+    const vector<WordID>& pos_sent = pos_[smeta.GetSentenceID()];
+    assert(edge.i_ < pos_sent.size());
+    out_context = pos_sent[edge.i_];
+    out_word_count = edge.rule_->EWords();
+    assert(out_word_count == 1); // this is only defined for lex translation!
+    // revisit this if you want to translate into null words
+  } else if (arity == 2) {
+    WordID left = *static_cast<const WordID*>(ant_contexts[0]);
+    WordID right = *static_cast<const WordID*>(ant_contexts[1]);
+    int left_wc = *(static_cast<const int*>(ant_contexts[0]) + 1);
+    int right_wc = *(static_cast<const int*>(ant_contexts[0]) + 1);
+    if (left_wc == 1 && right_wc == 1)
+      FireFeature(-1, left, features);
+    FireFeature(left, right, features);
+    out_word_count = left_wc + right_wc;
+    if (out_word_count == smeta.GetSourceLength())
+      FireFeature(right, -1, features);
+    out_context = right;
+  }
+}
+
 AlignerResults::AlignerResults(const std::string& param) :
     cur_sent_(-1),
     cur_grid_(NULL) {
diff --git a/decoder/ff_wordalign.h b/decoder/ff_wordalign.h
index 4a8b59c7..554dd23e 100644
--- a/decoder/ff_wordalign.h
+++ b/decoder/ff_wordalign.h
@@ -38,6 +38,26 @@ class MarkovJump : public FeatureFunction {
   std::string template_;
 };
 
+typedef std::map<WordID, int> Class2FID;
+typedef std::map<WordID, Class2FID> Class2Class2FID;
+class SourcePOSBigram : public FeatureFunction {
+ public:
+  SourcePOSBigram(const std::string& param);
+ protected:
+  virtual void TraversalFeaturesImpl(const SentenceMetadata& smeta,
+                                     const Hypergraph::Edge& edge,
+                                     const std::vector<const void*>& ant_contexts,
+                                     SparseVector<double>* features,
+                                     SparseVector<double>* estimated_features,
+                                     void* context) const;
+ private:
+  void FireFeature(WordID src,
+                   WordID trg,
+                   SparseVector<double>* features) const;
+  mutable Class2Class2FID fmap_;
+  std::vector<std::vector<WordID> > pos_;
+};
+
 class AlignerResults : public FeatureFunction {
  public:
   AlignerResults(const std::string& param);
diff --git a/decoder/lexcrf.cc b/decoder/lexcrf.cc
index 9f96de9f..b80d055c 100644
--- a/decoder/lexcrf.cc
+++ b/decoder/lexcrf.cc
@@ -46,7 +46,7 @@ struct LexicalCRFImpl {
     // hack to tell the feature function system how big the sentence pair is
     const int f_start = (use_null ? -1 : 0);
     int prev_node_id = -1;
-    for (int i = 0; i < e_len; ++i) {  // for each word in the *ref*
+    for (int i = 0; i < e_len; ++i) {  // for each word in the *target*
       Hypergraph::Node* node = forest->AddNode(kXCAT);
       const int new_node_id = node->id_;
       for (int j = f_start; j < f_len; ++j) { // for each word in the source
@@ -73,8 +73,8 @@ struct LexicalCRFImpl {
         const int comb_node_id = forest->AddNode(kXCAT)->id_;
         Hypergraph::TailNodeVector tail(2, prev_node_id);
         tail[1] = new_node_id;
-        const int edge_id = forest->AddEdge(kBINARY, tail)->id_;
-        forest->ConnectEdgeToHeadNode(edge_id, comb_node_id);
+        Hypergraph::Edge* edge = forest->AddEdge(kBINARY, tail);
+        forest->ConnectEdgeToHeadNode(edge->id_, comb_node_id);
         prev_node_id = comb_node_id;
       } else {
         prev_node_id = new_node_id;