kaldi-rnnlm.cc
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// lm/kaldi-rnnlm.cc
// Copyright 2015 Guoguo Chen
// 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 <utility>
#include "lm/kaldi-rnnlm.h"
#include "util/stl-utils.h"
#include "util/text-utils.h"
namespace kaldi {
KaldiRnnlmWrapper::KaldiRnnlmWrapper(
const KaldiRnnlmWrapperOpts &opts,
const std::string &unk_prob_rspecifier,
const std::string &word_symbol_table_rxfilename,
const std::string &rnnlm_rxfilename) {
rnnlm_.setRnnLMFile(rnnlm_rxfilename);
rnnlm_.setRandSeed(1);
rnnlm_.setUnkSym(opts.unk_symbol);
rnnlm_.setUnkPenalty(unk_prob_rspecifier);
rnnlm_.restoreNet();
// Reads symbol table.
fst::SymbolTable *word_symbols = NULL;
if (!(word_symbols =
fst::SymbolTable::ReadText(word_symbol_table_rxfilename))) {
KALDI_ERR << "Could not read symbol table from file "
<< word_symbol_table_rxfilename;
}
label_to_word_.resize(word_symbols->NumSymbols() + 1);
for (int32 i = 0; i < label_to_word_.size() - 1; ++i) {
label_to_word_[i] = word_symbols->Find(i);
if (label_to_word_[i] == "") {
KALDI_ERR << "Could not find word for integer " << i << "in the word "
<< "symbol table, mismatched symbol table or you have discoutinuous "
<< "integers in your symbol table?";
}
}
label_to_word_[label_to_word_.size() - 1] = opts.eos_symbol;
eos_ = label_to_word_.size() - 1;
}
BaseFloat KaldiRnnlmWrapper::GetLogProb(
int32 word, const std::vector<int32> &wseq,
const std::vector<float> &context_in,
std::vector<float> *context_out) {
std::vector<std::string> wseq_symbols(wseq.size());
for (int32 i = 0; i < wseq_symbols.size(); ++i) {
KALDI_ASSERT(wseq[i] < label_to_word_.size());
wseq_symbols[i] = label_to_word_[wseq[i]];
}
return rnnlm_.computeConditionalLogprob(label_to_word_[word], wseq_symbols,
context_in, context_out);
}
RnnlmDeterministicFst::RnnlmDeterministicFst(int32 max_ngram_order,
KaldiRnnlmWrapper *rnnlm) {
KALDI_ASSERT(rnnlm != NULL);
max_ngram_order_ = max_ngram_order;
rnnlm_ = rnnlm;
// Uses empty history for <s>.
std::vector<Label> bos;
std::vector<float> bos_context(rnnlm->GetHiddenLayerSize(), 1.0);
state_to_wseq_.push_back(bos);
state_to_context_.push_back(bos_context);
wseq_to_state_[bos] = 0;
start_state_ = 0;
}
fst::StdArc::Weight RnnlmDeterministicFst::Final(StateId s) {
// At this point, we should have created the state.
KALDI_ASSERT(static_cast<size_t>(s) < state_to_wseq_.size());
std::vector<Label> wseq = state_to_wseq_[s];
BaseFloat logprob = rnnlm_->GetLogProb(rnnlm_->GetEos(), wseq,
state_to_context_[s], NULL);
return Weight(-logprob);
}
bool RnnlmDeterministicFst::GetArc(StateId s, Label ilabel, fst::StdArc *oarc) {
// At this point, we should have created the state.
KALDI_ASSERT(static_cast<size_t>(s) < state_to_wseq_.size());
std::vector<Label> wseq = state_to_wseq_[s];
std::vector<float> new_context(rnnlm_->GetHiddenLayerSize());
BaseFloat logprob = rnnlm_->GetLogProb(ilabel, wseq,
state_to_context_[s], &new_context);
wseq.push_back(ilabel);
if (max_ngram_order_ > 0) {
while (wseq.size() >= max_ngram_order_) {
// History state has at most <max_ngram_order_> - 1 words in the state.
wseq.erase(wseq.begin(), wseq.begin() + 1);
}
}
std::pair<const std::vector<Label>, StateId> wseq_state_pair(
wseq, static_cast<Label>(state_to_wseq_.size()));
// Attemps to insert the current <lseq_state_pair>. If the pair already exists
// then it returns false.
typedef MapType::iterator IterType;
std::pair<IterType, bool> result = wseq_to_state_.insert(wseq_state_pair);
// If the pair was just inserted, then also add it to <state_to_wseq_> and
// <state_to_context_>.
if (result.second == true) {
state_to_wseq_.push_back(wseq);
state_to_context_.push_back(new_context);
}
// Creates the arc.
oarc->ilabel = ilabel;
oarc->olabel = ilabel;
oarc->nextstate = result.first->second;
oarc->weight = Weight(-logprob);
return true;
}
} // namespace kaldi