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text_reader.h
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text_reader.h
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/*!
* Copyright (c) 2016 Microsoft Corporation. All rights reserved.
* Licensed under the MIT License. See LICENSE file in the project root for license information.
*/
#ifndef LIGHTGBM_UTILS_TEXT_READER_H_
#define LIGHTGBM_UTILS_TEXT_READER_H_
#include <LightGBM/utils/log.h>
#include <LightGBM/utils/pipeline_reader.h>
#include <LightGBM/utils/random.h>
#include <string>
#include <cstdio>
#include <functional>
#include <sstream>
#include <vector>
namespace LightGBM {
/*!
* \brief Read text data from file
*/
template<typename INDEX_T>
class TextReader {
public:
/*!
* \brief Constructor
* \param filename Filename of data
* \param is_skip_first_line True if need to skip header
*/
TextReader(const char* filename, bool is_skip_first_line):
filename_(filename), is_skip_first_line_(is_skip_first_line) {
if (is_skip_first_line_) {
auto reader = VirtualFileReader::Make(filename);
if (!reader->Init()) {
Log::Fatal("Could not open %s", filename);
}
std::stringstream str_buf;
char read_c;
size_t nread = reader->Read(&read_c, 1);
while (nread == 1) {
if (read_c == '\n' || read_c == '\r') {
break;
}
str_buf << read_c;
++skip_bytes_;
nread = reader->Read(&read_c, 1);
}
if (read_c == '\r') {
reader->Read(&read_c, 1);
++skip_bytes_;
}
if (read_c == '\n') {
reader->Read(&read_c, 1);
++skip_bytes_;
}
first_line_ = str_buf.str();
Log::Debug("Skipped header \"%s\" in file %s", first_line_.c_str(), filename_);
}
}
/*!
* \brief Destructor
*/
~TextReader() {
Clear();
}
/*!
* \brief Clear cached data
*/
inline void Clear() {
lines_.clear();
lines_.shrink_to_fit();
}
/*!
* \brief return first line of data
*/
inline std::string first_line() {
return first_line_;
}
/*!
* \brief Get text data that read from file
* \return Text data, store in std::vector by line
*/
inline std::vector<std::string>& Lines() { return lines_; }
INDEX_T ReadAllAndProcess(const std::function<void(INDEX_T, const char*, size_t)>& process_fun) {
last_line_ = "";
INDEX_T total_cnt = 0;
PipelineReader::Read(filename_, skip_bytes_,
[&]
(const char* buffer_process, size_t read_cnt) {
size_t cnt = 0;
size_t i = 0;
size_t last_i = 0;
// skip the break between \r and \n
if (last_line_.size() == 0 && buffer_process[0] == '\n') {
i = 1;
last_i = i;
}
while (i < read_cnt) {
if (buffer_process[i] == '\n' || buffer_process[i] == '\r') {
if (last_line_.size() > 0) {
last_line_.append(buffer_process + last_i, i - last_i);
process_fun(total_cnt, last_line_.c_str(), last_line_.size());
last_line_ = "";
} else {
process_fun(total_cnt, buffer_process + last_i, i - last_i);
}
++cnt;
++i;
++total_cnt;
// skip end of line
while ((buffer_process[i] == '\n' || buffer_process[i] == '\r') && i < read_cnt) { ++i; }
last_i = i;
} else {
++i;
}
}
if (last_i != read_cnt) {
last_line_.append(buffer_process + last_i, read_cnt - last_i);
}
return cnt;
});
// if last line of file doesn't contain end of line
if (last_line_.size() > 0) {
Log::Info("Warning: last line of %s has no end of line, still using this line", filename_);
process_fun(total_cnt, last_line_.c_str(), last_line_.size());
++total_cnt;
last_line_ = "";
}
return total_cnt;
}
/*!
* \brief Read all text data from file in memory
* \return number of lines of text data
*/
INDEX_T ReadAllLines() {
return ReadAllAndProcess(
[=](INDEX_T, const char* buffer, size_t size) {
lines_.emplace_back(buffer, size);
});
}
std::vector<char> ReadContent(size_t* out_len) {
std::vector<char> ret;
*out_len = 0;
auto reader = VirtualFileReader::Make(filename_);
if (!reader->Init()) {
return ret;
}
const size_t buffer_size = 16 * 1024 * 1024;
auto buffer_read = std::vector<char>(buffer_size);
size_t read_cnt = 0;
do {
read_cnt = reader->Read(buffer_read.data(), buffer_size);
ret.insert(ret.end(), buffer_read.begin(), buffer_read.begin() + read_cnt);
*out_len += read_cnt;
} while (read_cnt > 0);
return ret;
}
INDEX_T SampleFromFile(Random& random, INDEX_T sample_cnt, std::vector<std::string>* out_sampled_data) {
INDEX_T cur_sample_cnt = 0;
return ReadAllAndProcess(
[&]
(INDEX_T line_idx, const char* buffer, size_t size) {
if (cur_sample_cnt < sample_cnt) {
out_sampled_data->emplace_back(buffer, size);
++cur_sample_cnt;
} else {
const size_t idx = static_cast<size_t>(random.NextInt(0, static_cast<int>(line_idx + 1)));
if (idx < static_cast<size_t>(sample_cnt)) {
out_sampled_data->operator[](idx) = std::string(buffer, size);
}
}
});
}
/*!
* \brief Read part of text data from file in memory, use filter_fun to filter data
* \param filter_fun Function that perform data filter
* \param out_used_data_indices Store line indices that read text data
* \return The number of total data
*/
INDEX_T ReadAndFilterLines(const std::function<bool(INDEX_T)>& filter_fun, std::vector<INDEX_T>* out_used_data_indices) {
out_used_data_indices->clear();
INDEX_T total_cnt = ReadAllAndProcess(
[&]
(INDEX_T line_idx , const char* buffer, size_t size) {
bool is_used = filter_fun(line_idx);
if (is_used) { out_used_data_indices->push_back(line_idx); }
if (is_used) { lines_.emplace_back(buffer, size); }
});
return total_cnt;
}
INDEX_T SampleAndFilterFromFile(const std::function<bool(INDEX_T)>& filter_fun, std::vector<INDEX_T>* out_used_data_indices,
Random& random, INDEX_T sample_cnt, std::vector<std::string>* out_sampled_data) {
INDEX_T cur_sample_cnt = 0;
out_used_data_indices->clear();
INDEX_T total_cnt = ReadAllAndProcess(
[&]
(INDEX_T line_idx, const char* buffer, size_t size) {
bool is_used = filter_fun(line_idx);
if (is_used) { out_used_data_indices->push_back(line_idx); }
if (is_used) {
if (cur_sample_cnt < sample_cnt) {
out_sampled_data->emplace_back(buffer, size);
++cur_sample_cnt;
} else {
const size_t idx = static_cast<size_t>(random.NextInt(0, static_cast<int>(out_used_data_indices->size())));
if (idx < static_cast<size_t>(sample_cnt)) {
out_sampled_data->operator[](idx) = std::string(buffer, size);
}
}
}
});
return total_cnt;
}
INDEX_T CountLine() {
return ReadAllAndProcess(
[=](INDEX_T, const char*, size_t) {
});
}
INDEX_T ReadAllAndProcessParallelWithFilter(const std::function<void(INDEX_T, const std::vector<std::string>&)>& process_fun, const std::function<bool(INDEX_T, INDEX_T)>& filter_fun) {
last_line_ = "";
INDEX_T total_cnt = 0;
INDEX_T used_cnt = 0;
PipelineReader::Read(filename_, skip_bytes_,
[&]
(const char* buffer_process, size_t read_cnt) {
size_t cnt = 0;
size_t i = 0;
size_t last_i = 0;
INDEX_T start_idx = used_cnt;
// skip the break between \r and \n
if (last_line_.size() == 0 && buffer_process[0] == '\n') {
i = 1;
last_i = i;
}
while (i < read_cnt) {
if (buffer_process[i] == '\n' || buffer_process[i] == '\r') {
if (last_line_.size() > 0) {
last_line_.append(buffer_process + last_i, i - last_i);
if (filter_fun(used_cnt, total_cnt)) {
lines_.push_back(last_line_);
++used_cnt;
}
last_line_ = "";
} else {
if (filter_fun(used_cnt, total_cnt)) {
lines_.emplace_back(buffer_process + last_i, i - last_i);
++used_cnt;
}
}
++cnt;
++i;
++total_cnt;
// skip end of line
while ((buffer_process[i] == '\n' || buffer_process[i] == '\r') && i < read_cnt) { ++i; }
last_i = i;
} else {
++i;
}
}
process_fun(start_idx, lines_);
lines_.clear();
if (last_i != read_cnt) {
last_line_.append(buffer_process + last_i, read_cnt - last_i);
}
return cnt;
});
// if last line of file doesn't contain end of line
if (last_line_.size() > 0) {
Log::Info("Warning: last line of %s has no end of line, still using this line", filename_);
if (filter_fun(used_cnt, total_cnt)) {
lines_.push_back(last_line_);
process_fun(used_cnt, lines_);
}
lines_.clear();
++total_cnt;
++used_cnt;
last_line_ = "";
}
return total_cnt;
}
INDEX_T ReadAllAndProcessParallel(const std::function<void(INDEX_T, const std::vector<std::string>&)>& process_fun) {
return ReadAllAndProcessParallelWithFilter(process_fun, [](INDEX_T, INDEX_T) { return true; });
}
INDEX_T ReadPartAndProcessParallel(const std::vector<INDEX_T>& used_data_indices, const std::function<void(INDEX_T, const std::vector<std::string>&)>& process_fun) {
return ReadAllAndProcessParallelWithFilter(process_fun,
[&used_data_indices](INDEX_T used_cnt, INDEX_T total_cnt) {
if (static_cast<size_t>(used_cnt) < used_data_indices.size() && total_cnt == used_data_indices[used_cnt]) {
return true;
} else {
return false;
}
});
}
private:
/*! \brief Filename of text data */
const char* filename_;
/*! \brief Cache the read text data */
std::vector<std::string> lines_;
/*! \brief Buffer for last line */
std::string last_line_;
/*! \brief first line */
std::string first_line_ = "";
/*! \brief is skip first line */
bool is_skip_first_line_ = false;
/*! \brief is skip first line */
int skip_bytes_ = 0;
};
} // namespace LightGBM
#endif // LightGBM_UTILS_TEXT_READER_H_