From 671c21451542e2dd20e45b4033d44d8e8735f87b Mon Sep 17 00:00:00 2001
From: Chris Dyer <redpony@gmail.com>
Date: Thu, 3 Dec 2009 16:33:55 -0500
Subject: initial check in

---
 training/model1.cc | 103 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 103 insertions(+)
 create mode 100644 training/model1.cc

(limited to 'training/model1.cc')

diff --git a/training/model1.cc b/training/model1.cc
new file mode 100644
index 00000000..f571700f
--- /dev/null
+++ b/training/model1.cc
@@ -0,0 +1,103 @@
+#include <iostream>
+
+#include "lattice.h"
+#include "stringlib.h"
+#include "filelib.h"
+#include "ttables.h"
+#include "tdict.h"
+
+using namespace std;
+
+int main(int argc, char** argv) {
+  if (argc != 2) {
+    cerr << "Usage: " << argv[0] << " corpus.fr-en\n";
+    return 1;
+  }
+  const int ITERATIONS = 5;
+  const prob_t BEAM_THRESHOLD(0.0001);
+  TTable tt;
+  const WordID kNULL = TD::Convert("<eps>");
+  bool use_null = true;
+  TTable::Word2Word2Double was_viterbi;
+  for (int iter = 0; iter < ITERATIONS; ++iter) {
+    const bool final_iteration = (iter == (ITERATIONS - 1));
+    cerr << "ITERATION " << (iter + 1) << (final_iteration ? " (FINAL)" : "") << endl;
+    ReadFile rf(argv[1]);
+    istream& in = *rf.stream();
+    prob_t likelihood = prob_t::One();
+    double denom = 0.0;
+    int lc = 0;
+    bool flag = false;
+    while(true) {
+      string line;
+      getline(in, line);
+      if (!in) break;
+      ++lc;
+      if (lc % 1000 == 0) { cerr << '.'; flag = true; }
+      if (lc %50000 == 0) { cerr << " [" << lc << "]\n" << flush; flag = false; }
+      string ssrc, strg;
+      ParseTranslatorInput(line, &ssrc, &strg);
+      Lattice src, trg;
+      LatticeTools::ConvertTextToLattice(ssrc, &src);
+      LatticeTools::ConvertTextToLattice(strg, &trg);
+      assert(src.size() > 0);
+      assert(trg.size() > 0);
+      denom += 1.0;
+      vector<prob_t> probs(src.size() + 1);
+      for (int j = 0; j < trg.size(); ++j) {
+        const WordID& f_j = trg[j][0].label;
+        prob_t sum = prob_t::Zero();
+        if (use_null) {
+          probs[0] = tt.prob(kNULL, f_j);
+          sum += probs[0];
+        }
+        for (int i = 1; i <= src.size(); ++i) {
+          probs[i] = tt.prob(src[i-1][0].label, f_j);
+          sum += probs[i];
+        }
+        if (final_iteration) {
+          WordID max_i = 0;
+          prob_t max_p = prob_t::Zero();
+          if (use_null) {
+            max_i = kNULL;
+            max_p = probs[0];
+          }
+          for (int i = 1; i <= src.size(); ++i) {
+            if (probs[i] > max_p) {
+              max_p = probs[i];
+              max_i = src[i-1][0].label;
+            }
+          }
+          was_viterbi[max_i][f_j] = 1.0;
+        } else {
+          if (use_null)
+            tt.Increment(kNULL, f_j, probs[0] / sum);
+          for (int i = 1; i <= src.size(); ++i)
+            tt.Increment(src[i-1][0].label, f_j, probs[i] / sum);
+        }
+        likelihood *= sum;
+      }
+    }
+    if (flag) { cerr << endl; }
+    cerr << "  log likelihood: " << log(likelihood) << endl;
+    cerr << "    cross entopy: " << (-log(likelihood) / denom) << endl;
+    cerr << "      perplexity: " << pow(2.0, -log(likelihood) / denom) << endl;
+    if (!final_iteration) tt.Normalize();
+  }
+  for (TTable::Word2Word2Double::iterator ei = tt.ttable.begin(); ei != tt.ttable.end(); ++ei) {
+    const TTable::Word2Double& cpd = ei->second;
+    const TTable::Word2Double& vit = was_viterbi[ei->first];
+    const string& esym = TD::Convert(ei->first);
+    prob_t max_p = prob_t::Zero();
+    for (TTable::Word2Double::const_iterator fi = cpd.begin(); fi != cpd.end(); ++fi)
+      if (fi->second > max_p) max_p = prob_t(fi->second);
+    const prob_t threshold = max_p * BEAM_THRESHOLD;
+    for (TTable::Word2Double::const_iterator fi = cpd.begin(); fi != cpd.end(); ++fi) {
+      if (fi->second > threshold || (vit.count(fi->first) > 0)) {
+        cout << esym << ' ' << TD::Convert(fi->first) << ' ' << log(fi->second) << endl;
+      }
+    } 
+  }
+  return 0;
+}
+
-- 
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