Added CDER metric to use in MERT.

git-svn-id: https://mosesdecoder.svn.sourceforge.net/svnroot/mosesdecoder/trunk@4152 1f5c12ca-751b-0410-a591-d2e778427230

mert/CderScorer.cpp

@@ -0,0 +1,107 @@
+#include "CderScorer.h"
+
+#include <stdexcept>
+#include <iostream>
+#include <algorithm>
+
+CderScorer::CderScorer(const string& config) 
+    : StatisticsBasedScorer("CDER",config)
+{
+}
+
+void CderScorer::setReferenceFiles(const vector<string>& referenceFiles)
+{
+  //make sure reference data is clear
+  ref_sentences.clear();
+  
+  //load reference data
+  for (size_t rid = 0; rid < referenceFiles.size(); ++rid) {
+    ifstream refin(referenceFiles[rid].c_str());
+    if (!refin) {
+      throw runtime_error("Unable to open: " + referenceFiles[rid]);
+    }
+    ref_sentences.push_back(vector<sent_t>());
+    string line;
+    while (getline(refin,line)) {
+		sent_t encoded;
+		encode(line, encoded);
+		ref_sentences[rid].push_back(encoded);
+    }
+  }  
+}
+
+void CderScorer::prepareStatsVector(size_t sid, const string& text, vector<int>& stats)
+{
+	sent_t cand;
+	encode(text, cand);
+  
+    float max = -2;
+    for (size_t rid = 0; rid < ref_sentences.size(); ++rid)
+    {
+		sent_t& ref = ref_sentences[rid][sid];
+        vector<int> tmp = computeCD(cand, ref);
+		if (calculateScore(tmp) > max)
+        {
+            stats = tmp;
+        }
+    }
+}
+
+float CderScorer::calculateScore(const vector<int>& comps)
+{
+	if (comps.size() != 2)
+	{
+		throw runtime_error("Size of stat vector for CDER is not 2");
+	}
+
+	return 1 - (comps[0] / (float) comps[1]);
+}
+
+vector<int> CderScorer::computeCD(const sent_t& cand, const sent_t& ref)
+{
+	int I = cand.size() + 1;	// Number of inter-words positions in candidate sentence
+	int L = ref.size() + 1;		// Number of inter-words positions in reference sentence
+
+	
+	int l = 0;
+	vector<int>* row = new vector<int>(I);	// row[i] stores cost of cheapest path from (0,0) to (i,l) in CDER aligment grid. 
+
+	// Initialization of first row
+	(*row)[0] = 0;
+	for (int i = 1; i < I; ++i) (*row)[i] = 1;
+	
+	// Calculating costs for next row using costs from the previous row.
+	while (++l < L)
+	{
+		vector<int>* nextRow = new vector<int>(I);
+		for (int i = 0; i < I; ++i)
+		{
+			vector<int> possibleCosts;
+			if (i > 0)
+			{
+				possibleCosts.push_back((*nextRow)[i-1] + 1);							// Deletion
+				possibleCosts.push_back((*row)[i-1] + distance(ref[l-1], cand[i-1]));	// Substitution/Identity
+			}
+			possibleCosts.push_back((*row)[i] + 1);										// Insertion
+			(*nextRow)[i] = *min_element(possibleCosts.begin(), possibleCosts.end());
+		}
+
+		int LJ = 1 + *min_element(nextRow->begin(), nextRow->end());					// Cost of LongJumps is the same for all in the row
+
+		for (int i = 0; i < I; ++i)
+		{
+			(*nextRow)[i] = min((*nextRow)[i], LJ);										// LongJumps
+		}
+
+		delete row;
+		row = nextRow;
+	}
+
+
+	vector<int> stats(2);
+	stats[0] = *(row->rbegin());  // CD distance is the cost of path from (0,0) to (I,L)
+	stats[1] = ref.size();
+
+	delete row;
+	return stats;
+}

mert/CderScorer.h

@@ -0,0 +1,59 @@
+#ifndef __CDERSCORER_H__
+#define __CDERSCORER_H__
+
+#include <algorithm>
+#include <iostream>
+#include <string>
+#include <vector>
+#include "Types.h"
+#include "ScoreData.h"
+#include "Scorer.h"
+
+
+using namespace std;
+
+
+class CderScorer: public StatisticsBasedScorer
+{
+public:
+  CderScorer(const string& config);
+  virtual void setReferenceFiles(const vector<string>& referenceFiles);
+  virtual void prepareStats(size_t sid, const string& text, ScoreStats& entry)
+  {
+    vector<int> stats;
+    prepareStatsVector(sid, text, stats);
+
+    stringstream sout;
+    copy(stats.begin(),stats.end(),ostream_iterator<float>(sout," "));
+    string stats_str = sout.str();
+    entry.set(stats_str);
+  }
+  virtual void prepareStatsVector(size_t sid, const string& text, vector<int>& stats);
+
+  size_t NumberOfScores() {
+    return 2;
+  };
+
+  float calculateScore(const vector<int>& comps);
+
+private:
+  typedef vector<int> sent_t;
+  vector<vector<sent_t> > ref_sentences;
+
+  vector<int> computeCD(const sent_t& cand, const sent_t& ref);
+  int distance(int word1, int word2) 
+  {
+	  if (word1 == word2) 
+		  return 0;
+	  else 
+		  return 1;
+  }
+
+  //no copy
+  CderScorer(const CderScorer&);
+  ~CderScorer() {};
+  CderScorer& operator=(const CderScorer&);
+};
+
+
+#endif

mert/Makefile.am

@@ -27,7 +27,8 @@ TERsrc/tercalc.cpp \
 TERsrc/tinystr.cpp \
 TERsrc/tinyxmlerror.cpp \
 TERsrc/tools.cpp \
-TerScorer.cpp
+TerScorer.cpp \
+CderScorer.cpp
 
 extractor_SOURCES = Util.cpp \
      Timer.cpp \
@@ -57,7 +58,8 @@ TERsrc/tercalc.cpp \
 TERsrc/tinystr.cpp \
 TERsrc/tinyxmlerror.cpp \
 TERsrc/tools.cpp \
-TerScorer.cpp
+TerScorer.cpp \
+CderScorer.cpp
 
 mert_CPPFLAGS = -W -Wall -Wno-unused -ffor-scope -DTRACE_ENABLE
 extractor_CPPFLAGS = -W -Wall -Wno-unused -ffor-scope -DTRACE_ENABLE

mert/ScorerFactory.h

@@ -15,6 +15,7 @@
 #include "BleuScorer.h"
 #include "PerScorer.h"
 #include "TerScorer.h"
+#include "CderScorer.h"
 
 using namespace std;
 
@@ -27,6 +28,7 @@ public:
     types.push_back(string("BLEU"));
     types.push_back(string("PER"));
     types.push_back(string("TER"));
+    types.push_back(string("CDER"));
     return types;
   }
 
@@ -37,6 +39,8 @@ public:
       return (PerScorer*) new PerScorer(config);
     } else if (type == "TER") {
       return (TerScorer*) new TerScorer(config);
+    } else if (type == "CDER") {
+      return (CderScorer*) new CderScorer(config);
     } else {
       throw runtime_error("Unknown scorer type: " + type);
     }