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src/bin/logprob-to-post.cc 3.71 KB
8dcb6dfcb   Yannick Estève   first commit
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  // bin/logprob-to-post.cc
  
  // Copyright 2012  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"
  
  /* Convert a matrix of log-probabilities 
     to something of type Posterior, i.e. for each utterance, a
     vector<vector<pair<int32, BaseFloat> > >, which is a sparse representation
     of the probabilities.
     To avoid getting very tiny values making it non-sparse, we support
     thresholding, and this can either be done as a simple threshold, or (the
     default) a pseudo-random thing where you preserve the expectation, e.g.
     if the threshold is 0.01 and the value is 0.001, it will be zero with
     probability 0.9 and 0.01 with probability 0.1.
  */
  
  int main(int argc, char *argv[]) {
    using namespace kaldi;
    typedef kaldi::int32 int32;
    try {
      const char *usage =
          "Convert a matrix of log-probabilities (e.g. from nnet-logprob) to posteriors
  "
          "Usage:  logprob-to-post [options] <logprob-matrix-rspecifier> <posteriors-wspecifier>
  "
          "e.g.:
  "
          " nnet-logprob [args] | logprob-to-post ark:- ark:1.post
  "
          "Caution: in this particular example, the output would be posteriors of pdf-ids,
  "
          "rather than transition-ids (c.f. post-to-pdf-post)
  ";
      
      ParseOptions po(usage);
  
      BaseFloat min_post = 0.01;
      bool random_prune = true; // preserve expectations.
  
      po.Register("min-post", &min_post, "Minimum posterior we will output (smaller "
                  "ones are pruned).  Also see --random-prune");
      po.Register("random-prune", &random_prune, "If true, prune posteriors with a "
                  "randomized method that preserves expectations.");
      
      po.Read(argc, argv);
  
      if (po.NumArgs() != 2) {
        po.PrintUsage();
        exit(1);
      }
  
      std::string logprob_rspecifier = po.GetArg(1);
      std::string posteriors_wspecifier = po.GetArg(2);
  
      int32 num_done = 0;
      SequentialBaseFloatMatrixReader logprob_reader(logprob_rspecifier);
      PosteriorWriter posterior_writer(posteriors_wspecifier);
  
      for (; !logprob_reader.Done(); logprob_reader.Next()) {
        num_done++;
        const Matrix<BaseFloat> &logprobs = logprob_reader.Value();
        // Posterior is vector<vector<pair<int32, BaseFloat> > >
        Posterior post(logprobs.NumRows());
        for (int32 i = 0; i < logprobs.NumRows(); i++) {
          SubVector<BaseFloat> row(logprobs, i);
          for (int32 j = 0; j < row.Dim(); j++) {
            BaseFloat p = Exp(row(j));
            if (p >= min_post) {
              post[i].push_back(std::make_pair(j, p));
            } else if (random_prune && (p / min_post) >= RandUniform()) {
              post[i].push_back(std::make_pair(j, min_post));
            }
          }
        }
        posterior_writer.Write(logprob_reader.Key(), post);
      }
      KALDI_LOG << "Converted " << num_done << " log-prob matrices to posteriors.";
      return (num_done != 0 ? 0 : 1);
    } catch(const std::exception &e) {
      std::cerr << e.what();
      return -1;
    }
  }