From 4d47dbd7da0434de67ac619392d516c678e1f2ca Mon Sep 17 00:00:00 2001
From: Chris Dyer <redpony@gmail.com>
Date: Thu, 18 Feb 2010 17:06:59 -0500
Subject: add generative word alignment model and primitive EM trainer. Model 1
 and HMM are supported, without NULL source words

---
 training/mr_em_map_adapter.cc | 160 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 160 insertions(+)
 create mode 100644 training/mr_em_map_adapter.cc

(limited to 'training/mr_em_map_adapter.cc')

diff --git a/training/mr_em_map_adapter.cc b/training/mr_em_map_adapter.cc
new file mode 100644
index 00000000..a98e1b77
--- /dev/null
+++ b/training/mr_em_map_adapter.cc
@@ -0,0 +1,160 @@
+#include <iostream>
+#include <fstream>
+#include <cassert>
+#include <cmath>
+
+#include <boost/utility.hpp>
+#include <boost/program_options.hpp>
+#include <boost/program_options/variables_map.hpp>
+#include "boost/tuple/tuple.hpp"
+
+#include "fdict.h"
+#include "sparse_vector.h"
+
+using namespace std;
+namespace po = boost::program_options;
+
+// useful for EM models parameterized by a bunch of multinomials
+// this converts event counts (returned from cdec as feature expectations)
+// into different keys and values (which are lists of all the events,
+// conditioned on the key) for summing and normalization by a reducer
+
+void InitCommandLine(int argc, char** argv, po::variables_map* conf) {
+  po::options_description opts("Configuration options");
+  opts.add_options()
+        ("buffer_size,b", po::value<int>()->default_value(1), "Buffer size (in # of counts) before emitting counts")
+        ("format,f",po::value<string>()->default_value("b64"), "Encoding of the input (b64 or text)");
+  po::options_description clo("Command line options");
+  clo.add_options()
+        ("config", po::value<string>(), "Configuration file")
+        ("help,h", "Print this help message and exit");
+  po::options_description dconfig_options, dcmdline_options;
+  dconfig_options.add(opts);
+  dcmdline_options.add(opts).add(clo);
+  
+  po::store(parse_command_line(argc, argv, dcmdline_options), *conf);
+  if (conf->count("config")) {
+    ifstream config((*conf)["config"].as<string>().c_str());
+    po::store(po::parse_config_file(config, dconfig_options), *conf);
+  }
+  po::notify(*conf);
+
+  if (conf->count("help")) {
+    cerr << dcmdline_options << endl;
+    exit(1);
+  }
+}
+
+struct EventMapper {
+  int Map(int fid) {
+    int& cv = map_[fid];
+    if (!cv) {
+      cv = GetConditioningVariable(fid);
+    }
+    return cv;
+  }
+  void Clear() { map_.clear(); }
+ protected:
+  virtual int GetConditioningVariable(int fid) const = 0;
+ private:
+  map<int, int> map_;
+};
+
+struct LexAlignEventMapper : public EventMapper {
+ protected:
+  virtual int GetConditioningVariable(int fid) const {
+    const string& str = FD::Convert(fid);
+    size_t pos = str.rfind("_");
+    if (pos == string::npos || pos == 0 || pos >= str.size() - 1) {
+      cerr << "Bad feature for EM adapter: " << str << endl;
+      abort();
+    }
+    return FD::Convert(str.substr(0, pos));
+  }
+};
+
+int main(int argc, char** argv) {
+  po::variables_map conf;
+  InitCommandLine(argc, argv, &conf);
+
+  const bool use_b64 = conf["format"].as<string>() == "b64";
+  const int buffer_size = conf["buffer_size"].as<int>();
+
+  const string s_obj = "**OBJ**";
+  // 0<TAB>**OBJ**=12.2;Feat1=2.3;Feat2=-0.2;
+  // 0<TAB>**OBJ**=1.1;Feat1=1.0;
+
+  EventMapper* event_mapper = new LexAlignEventMapper;
+  map<int, SparseVector<double> > counts;
+  size_t total = 0;
+  while(cin) {
+    string line;
+    getline(cin, line);
+    if (line.empty()) continue;
+    int feat;
+    double val;
+    size_t i = line.find("\t");
+    assert(i != string::npos);
+    ++i;
+    SparseVector<double> g;
+    double obj = 0;
+    if (use_b64) {
+      if (!B64::Decode(&obj, &g, &line[i], line.size() - i)) {
+        cerr << "B64 decoder returned error, skipping!\n";
+        continue;
+      }
+    } else {       // text encoding - your counts will not be accurate!
+      while (i < line.size()) {
+        size_t start = i;
+        while (line[i] != '=' && i < line.size()) ++i;
+        if (i == line.size()) { cerr << "FORMAT ERROR\n"; break; }
+        string fname = line.substr(start, i - start);
+        if (fname == s_obj) {
+          feat = -1;
+        } else {
+          feat = FD::Convert(line.substr(start, i - start));
+        }
+        ++i;
+        start = i;
+        while (line[i] != ';' && i < line.size()) ++i;
+        if (i - start == 0) continue;
+        val = atof(line.substr(start, i - start).c_str());
+        ++i;
+        if (feat == -1) {
+          obj = val;
+        } else {
+          g.set_value(feat, val);
+        }
+      }
+    }
+    //cerr << "OBJ: " << obj << endl;
+    const SparseVector<double>& cg = g;
+    for (SparseVector<double>::const_iterator it = cg.begin(); it != cg.end(); ++it) {
+      const int cond_var = event_mapper->Map(it->first);
+      SparseVector<double>& cond_counts = counts[cond_var];
+      int delta = cond_counts.num_active();
+      cond_counts.add_value(it->first, it->second);
+      delta = cond_counts.num_active() - delta;
+      total += delta;
+    }
+    if (total > buffer_size) {
+      for (map<int, SparseVector<double> >::iterator it = counts.begin();
+           it != counts.end(); ++it) {
+        const SparseVector<double>& cc = it->second;
+        cout << FD::Convert(it->first) << '\t';
+        if (use_b64) {
+          B64::Encode(0.0, cc, &cout);
+        } else {
+          abort();
+        }
+        cout << endl;
+      }
+      cout << flush;
+      total = 0;
+      counts.clear();
+    }
+  }
+
+  return 0;
+}
+
-- 
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