PushSpecialClass Class Reference

Collaboration diagram for PushSpecialClass:

Public Member Functions
	PushSpecialClass (VectorFst< StdArc > *fst, float delta)

Private Types
typedef StdArc	Arc
typedef Arc::Weight	Weight
typedef Arc::StateId	StateId

Private Member Functions
double	TestAccuracy ()
void	Iterate (float delta)
void	ModifyFst ()

Private Attributes
StateId	num_states_
StateId	initial_state_
std::vector< double >	occ_
double	lambda_
std::vector< std::vector< std::pair< StateId, double > > >	pred_
VectorFst< StdArc > *	fst_

Detailed Description

Definition at line 86 of file push-special.cc.

Member Typedef Documentation

Arc

typedef StdArc Arc

private

Definition at line 87 of file push-special.cc.

StateId

typedef Arc::StateId StateId

private

Definition at line 89 of file push-special.cc.

Weight

typedef Arc::Weight Weight

private

Definition at line 88 of file push-special.cc.

Constructor & Destructor Documentation

PushSpecialClass()

PushSpecialClass ( VectorFst< StdArc > *  fst, float  delta  )

inline

Definition at line 93 of file push-special.cc.

References kaldi::Exp(), PushSpecialClass::fst_, PushSpecialClass::initial_state_, PushSpecialClass::Iterate(), PushSpecialClass::ModifyFst(), PushSpecialClass::num_states_, PushSpecialClass::occ_, and PushSpecialClass::pred_.

                               : fst_(fst) {
    num_states_ = fst_->NumStates();
    initial_state_ = fst_->Start();
    occ_.resize(num_states_, 1.0 / sqrt(num_states_)); // unit length

    pred_.resize(num_states_);
    for (StateId s = 0; s < num_states_; s++) {
      for (ArcIterator<VectorFst<StdArc> > aiter(*fst, s);
           !aiter.Done(); aiter.Next()) {
        const Arc &arc = aiter.Value();
        StateId t = arc.nextstate;
        double weight = kaldi::Exp(-arc.weight.Value());
        pred_[t].push_back(std::make_pair(s, weight));
      }
      double final = kaldi::Exp(-fst_->Final(s).Value());
      if (final != 0.0)
        pred_[initial_state_].push_back(std::make_pair(s, final));
    }
    Iterate(delta);
    ModifyFst();
  }

Member Function Documentation

Iterate()

void Iterate ( float  delta )

inlineprivate

Definition at line 143 of file push-special.cc.

References rnnlm::i, rnnlm::j, KALDI_VLOG, KALDI_WARN, PushSpecialClass::lambda_, PushSpecialClass::num_states_, PushSpecialClass::occ_, PushSpecialClass::pred_, and PushSpecialClass::TestAccuracy().

Referenced by PushSpecialClass::PushSpecialClass().

                            {
    // This is like the power method to find the top eigenvalue of a matrix.
    // We limit it to 200 iters max, just in case something unanticipated
    // happens, but we should exit due to the "delta" thing, usually after
    // several tens of iterations.
    int iter, max_iter = 200;

    for (iter = 0; iter < max_iter; iter++) {
      std::vector<double> new_occ(num_states_);
      // We initialize new_occ to 0.1 * occ.  A simpler algorithm would
      // initialize them to zero, so it's like the pure power method.  This is
      // like the power method on (M + 0.1 I), and we do it this way to avoid a
      // problem we encountered with certain very simple linear FSTs where the
      // eigenvalues of the weight matrix (including negative and imaginary
      // ones) all have the same magnitude.
      for (int i = 0; i < num_states_; i++)
        new_occ[i] = 0.1 * occ_[i];

      for (int i = 0; i < num_states_; i++) {
        std::vector<std::pair<StateId, double> >::const_iterator iter,
            end = pred_[i].end();
        for (iter = pred_[i].begin(); iter != end; ++iter) {
          StateId j = iter->first;
          double p = iter->second;
          new_occ[j] += occ_[i] * p;
        }
      }
      double sumsq = 0.0;
      for (int i = 0; i < num_states_; i++) sumsq += new_occ[i] * new_occ[i];
      lambda_ = std::sqrt(sumsq);
      double inv_lambda = 1.0 / lambda_;
      for (int i = 0; i < num_states_; i++) occ_[i] = new_occ[i] * inv_lambda;
      KALDI_VLOG(4) << "Lambda is " << lambda_;
      if (iter % 5 == 0 && iter > 0 && TestAccuracy() <= delta) {
        KALDI_VLOG(3) << "Weight-pushing converged after " << iter
                      << " iterations.";
        return;
      }
    }
    KALDI_WARN << "push-special: finished " << iter
               << " iterations without converging.  Output will be inaccurate.";
  }

ModifyFst()

void ModifyFst ( )

inlineprivate

Definition at line 188 of file push-special.cc.

References PushSpecialClass::fst_, PushSpecialClass::initial_state_, KALDI_ISINF, KALDI_ISNAN, KALDI_WARN, kaldi::Log(), PushSpecialClass::num_states_, PushSpecialClass::occ_, and fst::Times().

Referenced by PushSpecialClass::PushSpecialClass().

                   {
    // First get the potentials as negative-logs, like the values
    // in the FST.
    for (StateId s = 0; s < num_states_; s++) {
      occ_[s] = -kaldi::Log(occ_[s]);
      if (KALDI_ISNAN(occ_[s]) || KALDI_ISINF(occ_[s]))
        KALDI_WARN << "NaN or inf found: " << occ_[s];
    }
    for (StateId s = 0; s < num_states_; s++) {
      for (MutableArcIterator<VectorFst<StdArc> > aiter(fst_, s);
           !aiter.Done(); aiter.Next()) {
        Arc arc = aiter.Value();
        StateId t = arc.nextstate;
        arc.weight = Weight(arc.weight.Value() + occ_[t] - occ_[s]);
        aiter.SetValue(arc);
      }
      fst_->SetFinal(s, Times(fst_->Final(s).Value(),
                              Weight(occ_[initial_state_] - occ_[s])));
    }
  }

TestAccuracy()

double TestAccuracy ( )

inlineprivate

Definition at line 116 of file push-special.cc.

References kaldi::Exp(), PushSpecialClass::fst_, PushSpecialClass::initial_state_, KALDI_VLOG, kaldi::Log(), PushSpecialClass::num_states_, and PushSpecialClass::occ_.

Referenced by PushSpecialClass::Iterate().

                        { // returns the error (the difference
    // between the min and max weights).
    double min_sum = 0, max_sum = 0;
    for (StateId s = 0; s < num_states_; s++) {
      double sum = 0.0;
      for (ArcIterator<VectorFst<StdArc> > aiter(*fst_, s);
           !aiter.Done(); aiter.Next()) {
        const Arc &arc = aiter.Value();
        StateId t = arc.nextstate;
        sum += kaldi::Exp(-arc.weight.Value()) * occ_[t] / occ_[s];
      }
      sum += kaldi::Exp(-(fst_->Final(s).Value())) * occ_[initial_state_] / occ_[s];
      if (s == 0) {
        min_sum = sum;
        max_sum = sum;
      } else {
        min_sum = std::min(min_sum, sum);
        max_sum = std::max(max_sum, sum);
      }
   }
    KALDI_VLOG(4) << "min,max is " << min_sum << " " << max_sum;
    return kaldi::Log(max_sum / min_sum); // In FST world we'll actually
    // dealing with logs, so the log of the ratio is more suitable
    // to compare with delta (makes testing the algorithm easier).
  }

Member Data Documentation

fst_

VectorFst<StdArc>* fst_

private

Definition at line 219 of file push-special.cc.

Referenced by PushSpecialClass::ModifyFst(), PushSpecialClass::PushSpecialClass(), and PushSpecialClass::TestAccuracy().

initial_state_

StateId initial_state_

private

Definition at line 211 of file push-special.cc.

Referenced by PushSpecialClass::ModifyFst(), PushSpecialClass::PushSpecialClass(), and PushSpecialClass::TestAccuracy().

lambda_

double lambda_

private

Definition at line 213 of file push-special.cc.

Referenced by PushSpecialClass::Iterate().

num_states_

StateId num_states_

private

Definition at line 210 of file push-special.cc.

Referenced by PushSpecialClass::Iterate(), PushSpecialClass::ModifyFst(), PushSpecialClass::PushSpecialClass(), and PushSpecialClass::TestAccuracy().

occ_

std::vector<double> occ_

private

Definition at line 212 of file push-special.cc.

Referenced by PushSpecialClass::Iterate(), PushSpecialClass::ModifyFst(), PushSpecialClass::PushSpecialClass(), and PushSpecialClass::TestAccuracy().

pred_

std::vector<std::vector<std::pair<StateId, double> > > pred_

private

Definition at line 215 of file push-special.cc.

Referenced by PushSpecialClass::Iterate(), and PushSpecialClass::PushSpecialClass().

---

The documentation for this class was generated from the following file:

• fstext/push-special.cc