1 files changed, 74 insertions, 91 deletions

diff --git a/dtrain/score.cc b/dtrain/score.cc
index 1e98c11d..d08e87f3 100644
--- a/dtrain/score.cc
+++ b/dtrain/score.cc
@@ -1,166 +1,149 @@
 #include "score.h"
 
-
 namespace dtrain
 {
 
 
-/******************************************************************************
- * NGRAMS
- *
- *
- * make_ngrams
- *
- */
-typedef map<vector<WordID>, size_t> Ngrams;
 Ngrams
-make_ngrams( vector<WordID>& s, size_t N )
+make_ngrams(vector<WordID>& s, size_t N)
 {
   Ngrams ngrams;
   vector<WordID> ng;
-  for ( size_t i = 0; i < s.size(); i++ ) {
+  for (size_t i = 0; i < s.size(); i++) {
     ng.clear();
-    for ( size_t j = i; j < min( i+N, s.size() ); j++ ) {
-      ng.push_back( s[j] );
+    for (size_t j = i; j < min(i+N, s.size()); j++) {
+      ng.push_back(s[j]);
       ngrams[ng]++;
     }
   }
   return ngrams;
 }
 
-
-/*
- * ngram_matches
- *
- */
 NgramCounts
-make_ngram_counts( vector<WordID> hyp, vector<WordID> ref, size_t N )
+make_ngram_counts(vector<WordID> hyp, vector<WordID> ref, size_t N)
 {
-  Ngrams hyp_ngrams = make_ngrams( hyp, N );
-  Ngrams ref_ngrams = make_ngrams( ref, N );
-  NgramCounts counts( N );
+  Ngrams hyp_ngrams = make_ngrams(hyp, N);
+  Ngrams ref_ngrams = make_ngrams(ref, N);
+  NgramCounts counts(N);
   Ngrams::iterator it;
   Ngrams::iterator ti;
-  for ( it = hyp_ngrams.begin(); it != hyp_ngrams.end(); it++ ) {
-    ti = ref_ngrams.find( it->first );
-    if ( ti != ref_ngrams.end() ) {
-      counts.add( it->second, ti->second, it->first.size() - 1 );
+  for (it = hyp_ngrams.begin(); it != hyp_ngrams.end(); it++) {
+    ti = ref_ngrams.find(it->first);
+    if (ti != ref_ngrams.end()) {
+      counts.add(it->second, ti->second, it->first.size() - 1);
     } else {
-      counts.add( it->second, 0, it->first.size() - 1 );
+      counts.add(it->second, 0, it->first.size() - 1);
     }
   }
   return counts;
 }
 
-
-/******************************************************************************
- * SCORERS
- *
+/*
+ * bleu
  *
- * brevity_penaly
+ * as in "BLEU: a Method for Automatic Evaluation
+ *        of Machine Translation"
+ * (Papineni et al. '02)
  *
+ * NOTE: 0 if one n in {1..N} has 0 count
  */
 double
-brevity_penaly( const size_t hyp_len, const size_t ref_len )
+brevity_penaly(const size_t hyp_len, const size_t ref_len)
 {
-  if ( hyp_len > ref_len ) return 1;
-  return exp( 1 - (double)ref_len/(double)hyp_len );
+  if (hyp_len > ref_len) return 1;
+  return exp(1 - (double)ref_len/(double)hyp_len);
 }
-
-
-/*
- * bleu
- * as in "BLEU: a Method for Automatic Evaluation of Machine Translation" (Papineni et al. '02)
- * page TODO
- * 0 if for N one of the counts = 0
- */
 double
-bleu( NgramCounts& counts, const size_t hyp_len, const size_t ref_len,
-      size_t N, vector<float> weights  )
+bleu(NgramCounts& counts, const size_t hyp_len, const size_t ref_len,
+      size_t N, vector<float> weights )
 {
-  if ( hyp_len == 0 || ref_len == 0 ) return 0;
-  if ( ref_len < N ) N = ref_len;
+  if (hyp_len == 0 || ref_len == 0) return 0;
+  if (ref_len < N) N = ref_len;
   float N_ = (float)N;
-  if ( weights.empty() )
+  if (weights.empty())
   {
-    for ( size_t i = 0; i < N; i++ ) weights.push_back( 1/N_ );
+    for (size_t i = 0; i < N; i++) weights.push_back(1/N_);
   }
   double sum = 0;
-  for ( size_t i = 0; i < N; i++ ) {
-    if ( counts.clipped[i] == 0 || counts.sum[i] == 0 ) return 0;
-    sum += weights[i] * log( (double)counts.clipped[i] / (double)counts.sum[i] );
+  for (size_t i = 0; i < N; i++) {
+    if (counts.clipped[i] == 0 || counts.sum[i] == 0) return 0;
+    sum += weights[i] * log((double)counts.clipped[i] / (double)counts.sum[i]);
   }
-  return brevity_penaly( hyp_len, ref_len ) * exp( sum );
+  return brevity_penaly(hyp_len, ref_len) * exp(sum);
 }
 
-
 /*
- * stupid_bleu
- * as in "ORANGE: a Method for Evaluating Automatic Evaluation Metrics for Machine Translation (Lin & Och '04)
- * page TODO
- * 0 iff no 1gram match
+ * 'stupid' bleu
+ *
+ * as in "ORANGE: a Method for Evaluating
+ *        Automatic Evaluation Metrics
+ *        for Machine Translation"
+ * (Lin & Och '04)
+ *
+ * NOTE: 0 iff no 1gram match
  */
 double
-stupid_bleu( NgramCounts& counts, const size_t hyp_len, const size_t ref_len,
-             size_t N, vector<float> weights  )
+stupid_bleu(NgramCounts& counts, const size_t hyp_len, const size_t ref_len,
+             size_t N, vector<float> weights )
 {
-  if ( hyp_len == 0 || ref_len == 0 ) return 0;
-  if ( ref_len < N ) N = ref_len;
+  if (hyp_len == 0 || ref_len == 0) return 0;
+  if (ref_len < N) N = ref_len;
   float N_ = (float)N;
-  if ( weights.empty() )
+  if (weights.empty())
   {
-    for ( size_t i = 0; i < N; i++ ) weights.push_back( 1/N_ );
+    for (size_t i = 0; i < N; i++) weights.push_back(1/N_);
   }
   double sum = 0;
   float add = 0;
-  for ( size_t i = 0; i < N; i++ ) {
-    if ( i == 1 ) add = 1;
-    sum += weights[i] * log( ((double)counts.clipped[i] + add) / ((double)counts.sum[i] + add) );
+  for (size_t i = 0; i < N; i++) {
+    if (i == 1) add = 1;
+    sum += weights[i] * log(((double)counts.clipped[i] + add) / ((double)counts.sum[i] + add));
   }
-  return brevity_penaly( hyp_len, ref_len ) * exp( sum );
+  return brevity_penaly(hyp_len, ref_len) * exp(sum);
 }
 
-
 /*
- * smooth_bleu
- * as in "An End-to-End Discriminative Approach to Machine Translation" (Liang et al. '06)
- * page TODO
- * max. 0.9375
+ * smooth bleu
+ *
+ * as in "An End-to-End Discriminative Approach
+ *        to Machine Translation"
+ * (Liang et al. '06)
+ *
+ * NOTE: max is 0.9375
  */
 double
-smooth_bleu( NgramCounts& counts, const size_t hyp_len, const size_t ref_len,
-             const size_t N, vector<float> weights  )
+smooth_bleu(NgramCounts& counts, const size_t hyp_len, const size_t ref_len,
+            const size_t N, vector<float> weights )
 {
-  if ( hyp_len == 0 || ref_len == 0 ) return 0;
+  if (hyp_len == 0 || ref_len == 0) return 0;
   float N_ = (float)N;
-  if ( weights.empty() )
+  if (weights.empty())
   {
-    for ( size_t i = 0; i < N; i++ ) weights.push_back( 1/N_ );
+    for (size_t i = 0; i < N; i++) weights.push_back(1/N_);
   }
   double sum = 0;
   float j = 1;
-  for ( size_t i = 0; i < N; i++ ) {
-    if ( counts.clipped[i] == 0 || counts.sum[i] == 0) continue;
-    sum += exp((weights[i] * log((double)counts.clipped[i]/(double)counts.sum[i]))) / pow( 2, N_-j+1 );
+  for (size_t i = 0; i < N; i++) {
+    if (counts.clipped[i] == 0 || counts.sum[i] == 0) continue;
+    sum += exp((weights[i] * log((double)counts.clipped[i]/(double)counts.sum[i]))) / pow(2, N_-j+1);
     j++;
   }
-  return brevity_penaly( hyp_len, ref_len ) * sum;
+  return brevity_penaly(hyp_len, ref_len) * sum;
 }
 
-
 /*
- * approx_bleu
- * as in "Online Large-Margin Training for Statistical Machine Translation" (Watanabe et al. '07)
- * CHIANG, RESNIK, synt struct features
- * .9*
- * page TODO
+ * approx. bleu
  *
+ * as in "Online Large-Margin Training of Syntactic
+ *        and Structural Translation Features"
+ * (Chiang et al. '08)
  */
 double
-approx_bleu( NgramCounts& counts, const size_t hyp_len, const size_t ref_len,
-     const size_t N, vector<float> weights )
+approx_bleu(NgramCounts& counts, const size_t hyp_len, const size_t ref_len,
+            const size_t N, vector<float> weights)
 {
-  return bleu( counts, hyp_len, ref_len, N, weights );
+  return brevity_penaly(hyp_len, ref_len) 
+         * 0.9 * bleu(counts, hyp_len, ref_len, N, weights);
 }