glog和gflags两个模块的使用实例

// This program converts a set of images to a lmdb/leveldb by storing them
// as Datum proto buffers.
// Usage:
//   convert_imageset [FLAGS] ROOTFOLDER/ LISTFILE DB_NAME
//
// where ROOTFOLDER is the root folder that holds all the images, and LISTFILE
// should be a list of files as well as their labels, in the format as
//   subfolder1/file1.JPEG 7
//   ....

#include <algorithm>
#include <fstream>  // NOLINT(readability/streams)
#include <string>
#include <utility>
#include <vector>

#include "boost/scoped_ptr.hpp"
#include "gflags/gflags.h"
#include "glog/logging.h"//增加glog的头文件

#include "caffe/proto/caffe.pb.h"
#include "caffe/util/db.hpp"
#include "caffe/util/format.hpp"
#include "caffe/util/io.hpp"
#include "caffe/util/rng.hpp"

using namespace caffe;  // NOLINT(build/namespaces)
using std::pair;
using boost::scoped_ptr;
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命令行解析参数的定义在主函数的外面，类似全局变量，使用时“FLAGS_参数名”
DEFINE_bool(gray, false,
"When this option is on, treat images as grayscale ones");
DEFINE_bool(shuffle, false,
"Randomly shuffle the order of images and their labels");
DEFINE_string(backend, "lmdb",
"The backend {lmdb, leveldb} for storing the result");
DEFINE_int32(resize_width, 0, "Width images are resized to");
DEFINE_int32(resize_height, 0, "Height images are resized to");
DEFINE_bool(check_size, false,
"When this option is on, check that all the datum have the same size");
DEFINE_bool(encoded, false,
"When this option is on, the encoded image will be save in datum");
DEFINE_string(encode_type, "",
"Optional: What type should we encode the image as ('png','jpg',...).");
---------------------------------------------------------------------------

int main(int argc, char** argv) {
#ifdef USE_OPENCV
---------------------------------------------------------------------------
::google::InitGoogleLogging(argv[0]);//打印日志初始化
// Print output to stderr (while still logging)
FLAGS_alsologtostderr = 1;//也向标准输入设备输出信息，即写入文件，也在显示器上打印

#ifndef GFLAGS_GFLAGS_H_
namespace gflags = google;
#endif
//下面设置帮助信息
gflags::SetUsageMessage("Convert a set of images to the leveldb/lmdb\n"
"format used as input for Caffe.\n"
"Usage:\n"
"    convert_imageset [FLAGS] ROOTFOLDER/ LISTFILE DB_NAME\n"
"The ImageNet dataset for the training demo is at\n"
"    http://www.image-net.org/download-images\n"); gflags::ParseCommandLineFlags(&argc, &argv, true);
//解析命令行参数，参数true时，解析完参数后argc=1，argv只保留了argv[0]
//参数flase时，解析完参数后argc个数不变，argv顺序会变化

if (argc < 4) {//如果参数个数小于指定值，显示帮助信息
gflags::ShowUsageWithFlagsRestrict(argv[0], "tools/convert_imageset");
return 1;
}
//参数的使用
const bool is_color = !FLAGS_gray;
const bool check_size = FLAGS_check_size;
const bool encoded = FLAGS_encoded;
const string encode_type = FLAGS_encode_type;
--------------------------------------------------------------------------------
std::ifstream infile(argv[2]);
std::vector<std::pair<std::string, int> > lines;
std::string line;
size_t pos;
int label;
while (std::getline(infile, line)) {
pos = line.find_last_of(' ');
label = atoi(line.substr(pos + 1).c_str());
lines.push_back(std::make_pair(line.substr(0, pos), label));
}
if (FLAGS_shuffle) {
// randomly shuffle data
LOG(INFO) << "Shuffling data";
shuffle(lines.begin(), lines.end());
}
LOG(INFO) << "A total of " << lines.size() << " images.";

if (encode_type.size() && !encoded)
LOG(INFO) << "encode_type specified, assuming encoded=true.";

int resize_height = std::max<int>(0, FLAGS_resize_height);
int resize_width = std::max<int>(0, FLAGS_resize_width);

// Create new DB
scoped_ptr<db::DB> db(db::GetDB(FLAGS_backend));
db->Open(argv[3], db::NEW);
scoped_ptr<db::Transaction> txn(db->NewTransaction());

// Storing to db
std::string root_folder(argv[1]);
Datum datum;
int count = 0;
int data_size = 0;
bool data_size_initialized = false;

for (int line_id = 0; line_id < lines.size(); ++line_id) {
bool status;
std::string enc = encode_type;
if (encoded && !enc.size()) {
// Guess the encoding type from the file name
string fn = lines[line_id].first;
size_t p = fn.rfind('.');
if ( p == fn.npos )
LOG(WARNING) << "Failed to guess the encoding of '" << fn << "'";
enc = fn.substr(p);
std::transform(enc.begin(), enc.end(), enc.begin(), ::tolower);
}
status = ReadImageToDatum(root_folder + lines[line_id].first,
lines[line_id].second, resize_height, resize_width, is_color,
enc, &datum);
if (status == false) continue;
if (check_size) {
if (!data_size_initialized) {
data_size = datum.channels() * datum.height() * datum.width();
data_size_initialized = true;
} else {
const std::string& data = datum.data();
CHECK_EQ(data.size(), data_size) << "Incorrect data field size "
<< data.size();
}
}
// sequential
string key_str = caffe::format_int(line_id, 8) + "_" + lines[line_id].first;

// Put in db
string out;
CHECK(datum.SerializeToString(&out));
txn->Put(key_str, out);

if (++count % 1000 == 0) {
// Commit db
txn->Commit();
txn.reset(db->NewTransaction());
LOG(INFO) << "Processed " << count << " files.";
}
}
// write the last batch
if (count % 1000 != 0) {
txn->Commit();
LOG(INFO) << "Processed " << count << " files.";
}
#else
LOG(FATAL) << "This tool requires OpenCV; compile with USE_OPENCV.";
#endif  // USE_OPENCV
return 0;
}