// bin/get-post-on-ali.cc
  
  // Copyright 2013  Brno University of Technology (Author: Karel Vesely)
  //           2014  Johns Hopkins University (author: Daniel Povey)
  
  // See ../../COPYING for clarification regarding multiple authors
  //
  // Licensed under the Apache License, Version 2.0 (the "License");
  // you may not use this file except in compliance with the License.
  // You may obtain a copy of the License at
  //
  //  http://www.apache.org/licenses/LICENSE-2.0
  //
  // THIS CODE IS PROVIDED *AS IS* BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
  // KIND, EITHER EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION ANY IMPLIED
  // WARRANTIES OR CONDITIONS OF TITLE, FITNESS FOR A PARTICULAR PURPOSE,
  // MERCHANTABLITY OR NON-INFRINGEMENT.
  // See the Apache 2 License for the specific language governing permissions and
  // limitations under the License.
  
  
  #include "base/kaldi-common.h"
  #include "util/common-utils.h"
  #include "gmm/am-diag-gmm.h"
  #include "hmm/transition-model.h"
  #include "hmm/hmm-utils.h"
  #include "hmm/posterior.h"
  
  
  int main(int argc, char *argv[]) {
    using namespace kaldi;
    typedef kaldi::int32 int32;
    try {
      const char *usage =
          "Given input posteriors, e.g. derived from lattice-to-post, and an alignment
  "
          "typically derived from the best path of a lattice, outputs the probability in
  "
          "the posterior of the corresponding index in the alignment, or zero if it was
  "
          "not there.  These are output as a vector of weights, one per utterance.
  "
          "While, by default, lattice-to-post (as a source of posteriors) and sources of
  "
          "alignments such as lattice-best-path will output transition-ids as the index,
  "
          "it will generally make sense to either convert these to pdf-ids using
  "
          "post-to-pdf-post and ali-to-pdf respectively, or to phones using post-to-phone-post
  "
          "and (ali-to-phones --per-frame=true).  Since this program only sees the integer
  "
          "indexes, it does not care what they represent-- but of course they should match
  "
          "(e.g. don't input posteriors with transition-ids and alignments with pdf-ids).
  "
          "See http://kaldi-asr.org/doc/hmm.html#transition_model_identifiers for an
  "
          "explanation of these types of indexes.
  "
          "
  "
          "See also: post-to-tacc, weight-post, post-to-weights, reverse-weights
  "
          "
  "
          "Usage:  get-post-on-ali [options] <posteriors-rspecifier> <ali-rspecifier> <weights-wspecifier>
  "
          "e.g.: get-post-on-ali ark:post.ark ark,s,cs:ali.ark ark:weights.ark
  ";
  
      ParseOptions po(usage);
  
      po.Read(argc, argv);
  
      if (po.NumArgs() != 3) {
        po.PrintUsage();
        exit(1);
      }
  
      std::string posteriors_rspecifier = po.GetArg(1),
          alignments_rspecifier = po.GetArg(2),
          confidences_wspecifier = po.GetArg(3);
  
      int32 num_done = 0, num_no_alignment = 0;
      SequentialPosteriorReader posterior_reader(posteriors_rspecifier);
      RandomAccessInt32VectorReader alignments_reader(alignments_rspecifier);
      BaseFloatVectorWriter confidences_writer(confidences_wspecifier);
  
      for (; !posterior_reader.Done(); posterior_reader.Next()) {
        std::string key = posterior_reader.Key();
        if (!alignments_reader.HasKey(key)) {
          num_no_alignment++;
        } else {
          //get the posterior
          const kaldi::Posterior &posterior = posterior_reader.Value();
          int32 num_frames = static_cast<int32>(posterior.size());
          //get the alignment
          const std::vector<int32> &alignment = alignments_reader.Value(key);
          //check the lengths match
          KALDI_ASSERT(num_frames == alignment.size());
  
          //fill the vector with posteriors on the alignment (under the alignment path)
          Vector<BaseFloat> confidence(num_frames);
          for(int32 i = 0; i < num_frames; i++) {
            BaseFloat post_i = 0.0;
            for(int32 j = 0; j < posterior[i].size(); j++) {
              if(alignment[i] == posterior[i][j].first) {
                post_i = posterior[i][j].second;
                break;
              }
            }
            confidence(i) = post_i;
          }
  
          //write the vector with confidences
          confidences_writer.Write(key,confidence);
          num_done++;
        }
      }
      KALDI_LOG << "Done getting the posteriors under the alignment path for "
                << num_done << " utterances. " << num_no_alignment << " with missing alignments.";
      return 0;
    } catch(const std::exception &e) {
      std::cerr << e.what();
      return -1;
    }
  }