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62 lines
2.2 KiB
62 lines
2.2 KiB
// Copyright (c) 2021 PaddlePaddle Authors. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "COPYING.APACHE2.0");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include "ctc_greedy_decoder.h"
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#include "decoder_utils.h"
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std::string ctc_greedy_decoder(
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const std::vector<std::vector<double>> &probs_seq,
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const std::vector<std::string> &vocabulary,
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size_t blank_id) {
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// dimension check
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size_t num_time_steps = probs_seq.size();
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for (size_t i = 0; i < num_time_steps; ++i) {
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VALID_CHECK_EQ(probs_seq[i].size(),
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vocabulary.size(),
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"The shape of probs_seq does not match with "
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"the shape of the vocabulary");
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}
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// size_t blank_id = vocabulary.size();
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std::vector<size_t> max_idx_vec(num_time_steps, 0);
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std::vector<size_t> idx_vec;
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for (size_t i = 0; i < num_time_steps; ++i) {
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double max_prob = 0.0;
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size_t max_idx = 0;
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const std::vector<double> &probs_step = probs_seq[i];
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for (size_t j = 0; j < probs_step.size(); ++j) {
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if (max_prob < probs_step[j]) {
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max_idx = j;
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max_prob = probs_step[j];
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}
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}
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// id with maximum probability in current time step
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max_idx_vec[i] = max_idx;
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// deduplicate
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if ((i == 0) || ((i > 0) && max_idx_vec[i] != max_idx_vec[i - 1])) {
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idx_vec.push_back(max_idx_vec[i]);
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}
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}
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std::string best_path_result;
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for (size_t i = 0; i < idx_vec.size(); ++i) {
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if (idx_vec[i] != blank_id) {
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std::string ch = vocabulary[idx_vec[i]];
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best_path_result += (ch == kSPACE) ? tSPACE : ch;
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}
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}
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return best_path_result;
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}
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