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// Copyright 2016 Google Inc.
//
// 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
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.!
#include <cmath>
#include <string>
#include <unordered_map>
#include "third_party/absl/strings/string_view.h"
#include "util.h"
#include "word_model.h"
#include "word_model_trainer.h"
namespace sentencepiece {
namespace word {
util::Status Trainer::Train() {
RETURN_IF_ERROR(status());
CHECK_OR_RETURN(normalizer_spec_.escape_whitespaces());
CHECK_EQ_OR_RETURN(TrainerSpec::WORD, trainer_spec_.model_type());
RETURN_IF_ERROR(LoadSentences());
std::unordered_map<std::string, uint64> freq;
for (const auto &it : sentences_) {
for (const auto &s : SplitIntoWords(it.first)) {
freq[std::string(s)] += it.second;
}
}
const int vocab_size = trainer_spec_.vocab_size() - meta_pieces_.size();
CHECK_GE_OR_RETURN(vocab_size, 0);
uint64 sum = 0;
for (const auto &it : freq) {
sum += it.second;
}
const float logsum = log(sum);
CHECK_OR_RETURN(final_pieces_.empty());
for (const auto &it : Sorted(freq)) {
if (it.first.find(kUNKStr) != std::string::npos) {
continue;
}
if (!trainer_spec_.use_all_vocab() &&
final_pieces_.size() == static_cast<size_t>(vocab_size)) {
break;
}
final_pieces_.emplace_back(it.first, log(it.second) - logsum);
}
if (trainer_spec_.use_all_vocab()) {
trainer_spec_.set_vocab_size(final_pieces_.size() + meta_pieces_.size());
}
return Save();
}
} // namespace word
} // namespace sentencepiece
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