From b6e699cb65f3f6e603434a7e702f8d46df4881ec Mon Sep 17 00:00:00 2001
From: Chris Dyer <cdyer@cs.cmu.edu>
Date: Thu, 17 Mar 2011 22:29:43 -0400
Subject: enable weights to be frozen during training

---
 training/mpi_online_optimize.cc | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/training/mpi_online_optimize.cc b/training/mpi_online_optimize.cc
index 325ba030..1367581a 100644
--- a/training/mpi_online_optimize.cc
+++ b/training/mpi_online_optimize.cc
@@ -64,6 +64,7 @@ bool InitCommandLine(int argc, char** argv, po::variables_map* conf) {
   po::options_description opts("Configuration options");
   opts.add_options()
         ("input_weights,w",po::value<string>(),"Input feature weights file")
+        ("frozen_features,z",po::value<string>(), "List of features not to optimize")
         ("training_data,t",po::value<string>(),"Training data corpus")
         ("training_agenda,a",po::value<string>(), "Text file listing a series of configuration files and the number of iterations to train using each configuration successively")
         ("minibatch_size_per_proc,s", po::value<unsigned>()->default_value(5), "Number of training instances evaluated per processor in each minibatch")
@@ -254,6 +255,20 @@ int main(int argc, char** argv) {
   if (conf.count("input_weights"))
     weights.InitFromFile(conf["input_weights"].as<string>());
 
+  vector<int> frozen_fids;
+  if (conf.count("frozen_features")) {
+    ReadFile rf(conf["frozen_features"].as<string>());
+    istream& in = *rf.stream();
+    string line;
+    while(in) {
+      getline(in, line);
+      if (line.empty()) continue;
+      if (line[0] == ' ' || line[line.size() - 1] == ' ') { line = Trim(line); }
+      frozen_fids.push_back(FD::Convert(line));
+    }
+    if (rank == 0) cerr << "Freezing " << frozen_fids.size() << " features.\n";
+  }
+
   vector<string> corpus;
   vector<int> ids;
   ReadTrainingCorpus(conf["training_data"].as<string>(), rank, size, &corpus, &ids);
@@ -362,6 +377,8 @@ int main(int argc, char** argv) {
       g.swap(local_grad);
 #endif
       local_grad.clear();
+      for (int i = 0; i < frozen_fids.size(); ++i)
+        g.erase(frozen_fids[i]);
       if (rank == 0) {
         g /= (size_per_proc * size);
         o->UpdateWeights(g, FD::NumFeats(), &x);
-- 
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