// fgmmbin/fgmm-global-merge.cc
  
  // Copyright 2009-2011  Microsoft Corporation
  
  // 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 "util/common-utils.h"
  #include "gmm/full-gmm.h"
  #include "gmm/mle-full-gmm.h"
  
  namespace kaldi {
  
  /// merges GMMs by appending Gaussians in "src" to "dst".
  /// Renormalizes weights by allocating weight proportional to #Gauss.
  void MergeFullGmm(const FullGmm &src, FullGmm *dst) {
    FullGmm dst_copy;
    dst_copy.CopyFromFullGmm(*dst);
    KALDI_ASSERT(src.NumGauss() != 0 && dst_copy.NumGauss()  != 0
                 && src.Dim() == dst_copy.Dim());
    int32 src_num_mix = src.NumGauss(), dst_num_mix = dst_copy.NumGauss(),
        num_mix = src_num_mix + dst_num_mix, dim = src.Dim();
    dst->Resize(num_mix, dim);
  
    std::vector<SpMatrix<BaseFloat> > invcovars(num_mix);
    for(int32 i = 0; i < dst_num_mix; i++) {
      invcovars[i].Resize(dim);
      invcovars[i].CopyFromSp(dst_copy.inv_covars()[i]);
    }
    for(int32 i = 0; i < src_num_mix; i++) {
      invcovars[i+dst_num_mix].Resize(dim);
      invcovars[i+dst_num_mix].CopyFromSp(src.inv_covars()[i]);
    }
    Matrix<BaseFloat> means_invcovars(num_mix, dim);
    means_invcovars.Range(0, dst_num_mix, 0, dim).CopyFromMat(dst_copy.means_invcovars());
    means_invcovars.Range(dst_num_mix, src_num_mix, 0, dim).CopyFromMat(src.means_invcovars());
    dst->SetInvCovarsAndMeansInvCovars(invcovars, means_invcovars);
  
    Vector<BaseFloat> weights(num_mix); // initialized to zero.
    // weight proportional to #Gaussians, so that if we combine a number of
    // models with same #Gaussians, they all get the same weight.
    BaseFloat src_weight = src_num_mix / static_cast<BaseFloat>(num_mix),
        dst_weight = dst_num_mix / static_cast<BaseFloat>(num_mix);
    weights.Range(0, dst_num_mix).AddVec(dst_weight, dst_copy.weights());
    weights.Range(dst_num_mix, src_num_mix).AddVec(src_weight, src.weights());
    dst->SetWeights(weights);
    dst->ComputeGconsts();
  }
  
  }
  
  
  int main(int argc, char *argv[]) {
    try {
      using namespace kaldi;
      typedef kaldi::int32 int32;
  
      const char *usage =
          "Combine a number of GMMs into a larger GMM, with #Gauss = 
  "
          "  sum(individual #Gauss)).  Output full GMM, and a text file with
  "
          "  sizes of each individual GMM.
  "
          "Usage: fgmm-global-merge [options] fgmm-out sizes-file-out fgmm-in1 fgmm-in2 ...
  ";
  
      bool binary = true;
      ParseOptions po(usage);
      po.Register("binary", &binary, "Write output in binary mode");
      po.Read(argc, argv);
  
      if (po.NumArgs() < 4) {
        po.PrintUsage();
        exit(1);
      }
  
      std::string fgmm_out_filename = po.GetArg(1),
          sizes_out_filename = po.GetArg(2);
  
      FullGmm fgmm;
      Output sizes_ko(sizes_out_filename, false); // false == not binary.
      
      for (int i = 3, max = po.NumArgs(); i <= max; i++) {
        std::string stats_in_filename = po.GetArg(i);
        bool binary_read;
        Input ki(stats_in_filename, &binary_read);
        if (i==3) {
          fgmm.Read(ki.Stream(), binary_read);
          sizes_ko.Stream() << fgmm.NumGauss() << ' ';
        } else {
          FullGmm fgmm2;
          fgmm2.Read(ki.Stream(), binary_read);
          sizes_ko.Stream() << fgmm2.NumGauss() << ' ';
          MergeFullGmm(fgmm2, &fgmm);
        }
      }
      sizes_ko.Stream() << "
  ";
      
      // Write out the model
      WriteKaldiObject(fgmm, fgmm_out_filename, binary);
      KALDI_LOG << "Written merged GMM to " << fgmm_out_filename;
    } catch(const std::exception &e) {
      std::cerr << e.what() << '
  ';
      return -1;
    }
  }