bilingual features for VW

2 files changed, 20 insertions, 2 deletions

diff --git a/moses/FF/VW/VW.cpp b/moses/FF/VW/VW.cpp
index 5111ff8ed..06acac6c6 100644
--- a/moses/FF/VW/VW.cpp
+++ b/moses/FF/VW/VW.cpp
@@ -273,13 +273,16 @@ void VW::EvaluateTranslationOptionListWithSourceContext(const InputType &input
         targetContext.AddWord(m_sentenceStartWord);
 
       const Phrase *targetSent = GetStored()->m_sentence;
-      const AlignmentInfo *alignInfo = GetStored()->m_alignment;
+
+      // word alignment info shifted by context size
+      AlignmentInfo contextAlignment = TransformAlignmentInfo(*GetStored()->m_alignment, maxContextSize, currentStart);
+
       if (currentStart > 0)
         targetContext.Append(targetSent->GetSubString(Range(0, currentStart - 1)));
 
       // extract target-context features
       for(size_t i = 0; i < contextFeatures.size(); ++i)
-        (*contextFeatures[i])(input, targetContext, *alignInfo, classifier, dummyVector);
+        (*contextFeatures[i])(input, targetContext, contextAlignment, classifier, dummyVector);
 
       // go over topts, extract target side features and train the classifier
       for (size_t toptIdx = 0; toptIdx < translationOptionList.size(); toptIdx++) {
@@ -479,6 +482,17 @@ const AlignmentInfo *VW::TransformAlignmentInfo(const Hypothesis &curHypo, size_
   return AlignmentInfoCollection::Instance().Add(alignmentPoints);
 }
 
+AlignmentInfo VW::TransformAlignmentInfo(const AlignmentInfo &alignInfo, size_t contextSize, int currentStart) const {
+  std::set<std::pair<size_t, size_t> > alignmentPoints;
+  for (int i = std::max(0, currentStart - (int)contextSize); i < currentStart; i++) {
+    std::set<size_t> alignedToTgt = alignInfo.GetAlignmentsForTarget(i);
+    BOOST_FOREACH(size_t srcIdx, alignedToTgt) {
+      alignmentPoints.insert(std::make_pair(srcIdx, i + contextSize));
+    }
+  }
+  return AlignmentInfo(alignmentPoints);
+}
+
 std::pair<bool, int> VW::IsCorrectTranslationOption(const TranslationOption &topt) const {
 
   //std::cerr << topt.GetSourceWordsRange() << std::endl;
diff --git a/moses/FF/VW/VW.h b/moses/FF/VW/VW.h
index ea17188f7..89891e725 100644
--- a/moses/FF/VW/VW.h
+++ b/moses/FF/VW/VW.h
@@ -153,6 +153,10 @@ private:
   // to positions in contextPhrase)
   const AlignmentInfo *TransformAlignmentInfo(const Hypothesis &curHypo, size_t contextSize) const;
 
+  // used during training to extract relevant alignment points from the full sentence alignment
+  // and shift them by target context size
+  AlignmentInfo TransformAlignmentInfo(const AlignmentInfo &alignInfo, size_t contextSize, int currentStart) const;
+
   // At training time, determine whether a translation option is correct for the current target sentence
   // based on word alignment. This is a bit complicated because we need to handle various corner-cases
   // where some word(s) on phrase borders are unaligned.