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PaddleSpeech/paddlespeech/s2t/decoders/ctcdecoder/swig/decoder_utils.cpp

194 lines
6.0 KiB

// Copyright (c) 2021 PaddlePaddle Authors. All Rights Reserved.
//
// 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 "decoder_utils.h"
#include <algorithm>
#include <cmath>
#include <limits>
std::vector<std::pair<size_t, float>> get_pruned_log_probs(
const std::vector<double> &prob_step,
double cutoff_prob,
size_t cutoff_top_n) {
std::vector<std::pair<int, double>> prob_idx;
for (size_t i = 0; i < prob_step.size(); ++i) {
prob_idx.push_back(std::pair<int, double>(i, prob_step[i]));
}
// pruning of vacobulary
size_t cutoff_len = prob_step.size();
if (cutoff_prob < 1.0 || cutoff_top_n < cutoff_len) {
std::sort(prob_idx.begin(),
prob_idx.end(),
pair_comp_second_rev<int, double>);
if (cutoff_prob < 1.0) {
double cum_prob = 0.0;
cutoff_len = 0;
for (size_t i = 0; i < prob_idx.size(); ++i) {
cum_prob += prob_idx[i].second;
cutoff_len += 1;
if (cum_prob >= cutoff_prob || cutoff_len >= cutoff_top_n)
break;
}
}
prob_idx = std::vector<std::pair<int, double>>(
prob_idx.begin(), prob_idx.begin() + cutoff_len);
}
std::vector<std::pair<size_t, float>> log_prob_idx;
for (size_t i = 0; i < cutoff_len; ++i) {
log_prob_idx.push_back(std::pair<int, float>(
prob_idx[i].first, log(prob_idx[i].second + NUM_FLT_MIN)));
}
return log_prob_idx;
}
std::vector<std::pair<double, std::string>> get_beam_search_result(
const std::vector<PathTrie *> &prefixes,
const std::vector<std::string> &vocabulary,
size_t beam_size) {
// allow for the post processing
std::vector<PathTrie *> space_prefixes;
if (space_prefixes.empty()) {
for (size_t i = 0; i < beam_size && i < prefixes.size(); ++i) {
space_prefixes.push_back(prefixes[i]);
}
}
std::sort(space_prefixes.begin(), space_prefixes.end(), prefix_compare);
std::vector<std::pair<double, std::string>> output_vecs;
for (size_t i = 0; i < beam_size && i < space_prefixes.size(); ++i) {
std::vector<int> output;
space_prefixes[i]->get_path_vec(output);
// convert index to string
std::string output_str;
for (size_t j = 0; j < output.size(); j++) {
std::string ch = vocabulary[output[j]];
output_str += (ch == kSPACE) ? tSPACE : ch;
}
std::pair<double, std::string> output_pair(
-space_prefixes[i]->approx_ctc, output_str);
output_vecs.emplace_back(output_pair);
}
return output_vecs;
}
size_t get_utf8_str_len(const std::string &str) {
size_t str_len = 0;
for (char c : str) {
str_len += ((c & 0xc0) != 0x80);
}
return str_len;
}
std::vector<std::string> split_utf8_str(const std::string &str) {
std::vector<std::string> result;
std::string out_str;
for (char c : str) {
if ((c & 0xc0) != 0x80) // new UTF-8 character
{
if (!out_str.empty()) {
result.push_back(out_str);
out_str.clear();
}
}
out_str.append(1, c);
}
result.push_back(out_str);
return result;
}
std::vector<std::string> split_str(const std::string &s,
const std::string &delim) {
std::vector<std::string> result;
std::size_t start = 0, delim_len = delim.size();
while (true) {
std::size_t end = s.find(delim, start);
if (end == std::string::npos) {
if (start < s.size()) {
result.push_back(s.substr(start));
}
break;
}
if (end > start) {
result.push_back(s.substr(start, end - start));
}
start = end + delim_len;
}
return result;
}
bool prefix_compare(const PathTrie *x, const PathTrie *y) {
if (x->score == y->score) {
if (x->character == y->character) {
return false;
} else {
return (x->character < y->character);
}
} else {
return x->score > y->score;
}
}
void add_word_to_fst(const std::vector<int> &word,
fst::StdVectorFst *dictionary) {
if (dictionary->NumStates() == 0) {
fst::StdVectorFst::StateId start = dictionary->AddState();
assert(start == 0);
dictionary->SetStart(start);
}
fst::StdVectorFst::StateId src = dictionary->Start();
fst::StdVectorFst::StateId dst;
for (auto c : word) {
dst = dictionary->AddState();
dictionary->AddArc(src, fst::StdArc(c, c, 0, dst));
src = dst;
}
dictionary->SetFinal(dst, fst::StdArc::Weight::One());
}
bool add_word_to_dictionary(
const std::string &word,
const std::unordered_map<std::string, int> &char_map,
bool add_space,
int SPACE_ID,
fst::StdVectorFst *dictionary) {
auto characters = split_utf8_str(word);
std::vector<int> int_word;
for (auto &c : characters) {
if (c == " ") {
int_word.push_back(SPACE_ID);
} else {
auto int_c = char_map.find(c);
if (int_c != char_map.end()) {
int_word.push_back(int_c->second);
} else {
return false; // return without adding
}
}
}
if (add_space) {
int_word.push_back(SPACE_ID);
}
add_word_to_fst(int_word, dictionary);
return true; // return with successful adding
}