add compound splitting logic and features (Dyer 2008, NAACL)

1 files changed, 197 insertions, 0 deletions

diff --git a/src/ff_csplit.cc b/src/ff_csplit.cc
new file mode 100644
index 00000000..5d8dfefb
--- /dev/null
+++ b/src/ff_csplit.cc
@@ -0,0 +1,197 @@
+#include "ff_csplit.h"
+
+#include <set>
+#include <cstring>
+
+#include "tdict.h"
+#include "freqdict.h"
+#include "filelib.h"
+#include "stringlib.h"
+#include "tdict.h"
+
+#include "Vocab.h"
+#include "Ngram.h"
+
+using namespace std;
+
+struct BasicCSplitFeaturesImpl {
+  BasicCSplitFeaturesImpl(const string& param) :
+      word_count_(FD::Convert("WordCount")),
+      in_dict_(FD::Convert("InDict")),
+      short_(FD::Convert("Short")),
+      long_(FD::Convert("Long")),
+      oov_(FD::Convert("OOV")),
+      short_range_(FD::Convert("ShortRange")),
+      high_freq_(FD::Convert("HighFreq")),
+      med_freq_(FD::Convert("MedFreq")),
+      freq_(FD::Convert("Freq")),
+      bad_(FD::Convert("Bad")) {
+    vector<string> argv;
+    int argc = SplitOnWhitespace(param, &argv);
+    if (argc != 1 && argc != 2) {
+      cerr << "Expected: freqdict.txt [badwords.txt]\n";
+      abort();
+    }
+    freq_dict_.Load(argv[0]);
+    if (argc == 2) {
+      ReadFile rf(argv[1]);
+      istream& in = *rf.stream();
+      while(in) {
+        string badword;
+        in >> badword;
+        if (badword.empty()) continue;
+        bad_words_.insert(TD::Convert(badword));
+      }
+    }
+  }
+
+  void TraversalFeaturesImpl(const Hypergraph::Edge& edge,
+                             SparseVector<double>* features) const;
+
+  const int word_count_;
+  const int in_dict_;
+  const int short_;
+  const int long_;
+  const int oov_;
+  const int short_range_;
+  const int high_freq_;
+  const int med_freq_;
+  const int freq_;
+  const int bad_;
+  FreqDict freq_dict_;
+  set<WordID> bad_words_;
+};
+
+BasicCSplitFeatures::BasicCSplitFeatures(const string& param) :
+  pimpl_(new BasicCSplitFeaturesImpl(param)) {}
+
+void BasicCSplitFeaturesImpl::TraversalFeaturesImpl(
+                                     const Hypergraph::Edge& edge,
+                                     SparseVector<double>* features) const {
+  features->set_value(word_count_, 1.0);
+  const WordID word = edge.rule_->e_[1];
+  const char* sword = TD::Convert(word);
+  const int len = strlen(sword);
+  int cur = 0;
+  int chars = 0;
+  while(cur < len) {
+    cur += UTF8Len(sword[cur]);
+    ++chars;
+  }
+  bool has_sch = strstr(sword, "sch");
+  bool has_ch = (!has_sch && strstr(sword, "ch"));
+  bool has_ie = strstr(sword, "ie");
+  bool has_zw = strstr(sword, "zw");
+  if (has_sch) chars -= 2;
+  if (has_ch) --chars;
+  if (has_ie) --chars;
+  if (has_zw) --chars;
+
+  float freq = freq_dict_.LookUp(word);
+  if (freq) {
+    features->set_value(freq_, freq);
+    features->set_value(in_dict_, 1.0);
+  } else {
+    features->set_value(oov_, 1.0);
+    freq = 99.0f;
+  }
+  if (bad_words_.count(word) != 0)
+    features->set_value(bad_, 1.0);
+  if (chars < 5)
+    features->set_value(short_, 1.0);
+  if (chars > 10)
+    features->set_value(long_, 1.0);
+  if (freq < 7.0f)
+    features->set_value(high_freq_, 1.0);
+  if (freq > 8.0f && freq < 10.f)
+    features->set_value(med_freq_, 1.0);
+  if (freq < 10.0f && chars < 5)
+    features->set_value(short_range_, 1.0);
+}
+
+void BasicCSplitFeatures::TraversalFeaturesImpl(
+                                     const SentenceMetadata& smeta,
+                                     const Hypergraph::Edge& edge,
+                                     const std::vector<const void*>& ant_contexts,
+                                     SparseVector<double>* features,
+                                     SparseVector<double>* estimated_features,
+                                     void* out_context) const {
+  (void) smeta;
+  (void) ant_contexts;
+  (void) out_context;
+  (void) estimated_features;
+  if (edge.Arity() == 0) return;
+  if (edge.rule_->EWords() != 1) return;
+  pimpl_->TraversalFeaturesImpl(edge, features);
+}
+
+struct ReverseCharLMCSplitFeatureImpl {
+  ReverseCharLMCSplitFeatureImpl(const string& param) :
+      order_(5),
+      ngram_(vocab_, order_) {
+    kBOS = vocab_.getIndex("<s>");
+    kEOS = vocab_.getIndex("</s>");
+    File file(param.c_str(), "r", 0);
+    assert(file);
+    cerr << "Reading " << order_ << "-gram LM from " << param << endl;
+    ngram_.read(file);
+  }
+
+  double LeftPhonotacticProb(const char* word) {
+    for (int i = 0; i < order_; ++i)
+      sc[i] = kBOS;
+    const int len = strlen(word);
+    int cur = 0;
+    int chars = 0;
+    while(cur < len) {
+      cur += UTF8Len(word[cur]);
+      ++chars;
+    }
+    const int sp = min(chars, order_-1);
+    int wend = 0; cur = 0;
+    while(cur < sp) {
+      wend += UTF8Len(word[wend]);
+      ++cur;
+    }
+    int wi = 0;
+    int ci = (order_ - sp - 1);
+    // cerr << "WORD: " << word << endl;
+    while (wi != wend) {
+      const int clen = UTF8Len(word[wi]);
+      string cur_char(&word[wi], clen);
+      wi += clen;
+      // cerr << " char: " << cur_char << "  ci=" << ci << endl;
+      sc[ci++] = vocab_.getIndex(cur_char.c_str());
+    }
+    // cerr << "  END sp=" << sp << endl;
+    sc[sp] = Vocab_None;
+    const double startprob = -ngram_.wordProb(kEOS, sc);
+    // cerr << "  PROB=" << startprob << endl;
+    return startprob;
+  }
+ private:
+  const int order_;
+  Vocab vocab_;
+  VocabIndex kBOS;
+  VocabIndex kEOS;
+  Ngram ngram_;
+  VocabIndex sc[80];
+};
+
+ReverseCharLMCSplitFeature::ReverseCharLMCSplitFeature(const string& param) :
+  pimpl_(new ReverseCharLMCSplitFeatureImpl(param)),
+  fid_(FD::Convert("RevCharLM")) {}
+
+void ReverseCharLMCSplitFeature::TraversalFeaturesImpl(
+                                     const SentenceMetadata& smeta,
+                                     const Hypergraph::Edge& edge,
+                                     const std::vector<const void*>& ant_contexts,
+                                     SparseVector<double>* features,
+                                     SparseVector<double>* estimated_features,
+                                     void* out_context) const {
+  if (edge.Arity() != 1) return;
+  if (edge.rule_->EWords() != 1) return;
+  const double lpp = pimpl_->LeftPhonotacticProb(TD::Convert(edge.rule_->e_[1]));
+  features->set_value(fid_, lpp);
+}
+