From 3ddb62cc14f81500a2bf04cf09282e572cd05ece Mon Sep 17 00:00:00 2001
From: Chris Dyer <cdyer@cs.cmu.edu>
Date: Thu, 17 Feb 2011 23:41:29 -0500
Subject: more spans

---
 decoder/ff_spans.cc | 39 ++++++++++++++++++++++++++++++++++++++-
 decoder/ff_spans.h  |  5 +++++
 2 files changed, 43 insertions(+), 1 deletion(-)

diff --git a/decoder/ff_spans.cc b/decoder/ff_spans.cc
index b454c9fd..06593727 100644
--- a/decoder/ff_spans.cc
+++ b/decoder/ff_spans.cc
@@ -3,15 +3,41 @@
 #include <sstream>
 #include <cassert>
 
+#include "filelib.h"
 #include "sentence_metadata.h"
 #include "lattice.h"
 #include "fdict.h"
+#include "verbose.h"
 
 using namespace std;
 
 SpanFeatures::SpanFeatures(const string& param) :
   kS(TD::Convert("S") * -1),
-  kX(TD::Convert("X") * -1) {}
+  kX(TD::Convert("X") * -1) {
+  if (param.size() > 0) {
+    int lc = 0;
+    if (!SILENT) { cerr << "Reading word map for SpanFeatures from " << param << endl; }
+    ReadFile rf(param);
+    istream& in = *rf.stream();
+    string line;
+    vector<WordID> v;
+    while(in) {
+      ++lc;
+      getline(in, line);
+      if (line.empty()) continue;
+      v.clear();
+      TD::ConvertSentence(line, &v);
+      if (v.size() != 2) {
+        cerr << "Error reading line " << lc << ": " << line << endl;
+        abort();
+      }
+      word2class_[v[0]] = v[1];
+    }
+    word2class_[TD::Convert("<s>")] = TD::Convert("BOS");
+    word2class_[TD::Convert("</s>")] = TD::Convert("EOS");
+    oov_ = TD::Convert("OOV");
+  }
+}
 
 void SpanFeatures::TraversalFeaturesImpl(const SentenceMetadata& smeta,
                                          const Hypergraph::Edge& edge,
@@ -37,6 +63,13 @@ void SpanFeatures::TraversalFeaturesImpl(const SentenceMetadata& smeta,
   }
 }
 
+WordID SpanFeatures::MapIfNecessary(const WordID& w) const {
+  if (word2class_.empty()) return w;
+  map<WordID,WordID>::const_iterator it = word2class_.find(w);
+  if (it == word2class_.end()) return oov_;
+  return it->second;
+}
+
 void SpanFeatures::PrepareForInput(const SentenceMetadata& smeta) {
   const Lattice& lattice = smeta.GetSourceLattice();
   const WordID eos = TD::Convert("</s>");
@@ -48,8 +81,10 @@ void SpanFeatures::PrepareForInput(const SentenceMetadata& smeta) {
     WordID bword = bos;
     if (i > 0)
       bword = lattice[i-1][0].label;
+    bword = MapIfNecessary(bword);
     if (i < lattice.size())
       word = lattice[i][0].label;  // rather arbitrary for lattices
+    word = MapIfNecessary(word);
     ostringstream sfid;
     sfid << "ES:" << TD::Convert(word);
     end_span_ids_[i] = FD::Convert(sfid.str());
@@ -62,10 +97,12 @@ void SpanFeatures::PrepareForInput(const SentenceMetadata& smeta) {
     WordID bword = bos;
     if (i > 0)
       bword = lattice[i-1][0].label;
+    bword = MapIfNecessary(bword);
     for (int j = 0; j <= lattice.size(); ++j) {
       WordID word = eos;
       if (j < lattice.size())
         word = lattice[j][0].label;
+      word = MapIfNecessary(word);
       ostringstream pf;
       pf << "SS:" << TD::Convert(bword) << "_" << TD::Convert(word);
       span_feats_(i,j) = FD::Convert(pf.str());
diff --git a/decoder/ff_spans.h b/decoder/ff_spans.h
index 0446d062..5e90b7e0 100644
--- a/decoder/ff_spans.h
+++ b/decoder/ff_spans.h
@@ -2,8 +2,10 @@
 #define _FF_SPANS_H_
 
 #include <vector>
+#include <map>
 #include "ff.h"
 #include "array2d.h"
+#include "wordid.h"
 
 class SpanFeatures : public FeatureFunction {
  public:
@@ -17,11 +19,14 @@ class SpanFeatures : public FeatureFunction {
                                      void* context) const;
   virtual void PrepareForInput(const SentenceMetadata& smeta);
  private:
+  WordID MapIfNecessary(const WordID& w) const;
   const int kS;
   const int kX;
   Array2D<int> span_feats_;
   std::vector<int> end_span_ids_;
   std::vector<int> beg_span_ids_;
+  std::map<WordID, WordID> word2class_;  // optional projection to coarser class
+  WordID oov_;
 };
 
 #endif
-- 
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