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/**
* @file create_read_write_datasets.cpp
* @author Fangjun Kuang <csukuangfj dot at gmail dot com>
* @date December 2017
*
* @brief It demonstrates how to create a dataset, how
* to write a cv::Mat to the dataset and how to
* read a cv::Mat from it.
*
*/
//! [tutorial]
#include <iostream>
#include <opencv2/core.hpp>
#include <opencv2/hdf.hpp>
using namespace cv;
static void write_root_group_single_channel()
{
String filename = "root_group_single_channel.h5";
String dataset_name = "/single"; // Note that it is a child of the root group /
// prepare data
Mat data;
data = (cv::Mat_<float>(2, 3) << 0, 1, 2, 3, 4, 5, 6);
//! [tutorial_open_file]
Ptr<hdf::HDF5> h5io = hdf::open(filename);
//! [tutorial_open_file]
//! [tutorial_write_root_single_channel]
// write data to the given dataset
// the dataset "/single" is created automatically, since it is a child of the root
h5io->dswrite(data, dataset_name);
//! [tutorial_write_root_single_channel]
//! [tutorial_read_dataset]
Mat expected;
h5io->dsread(expected, dataset_name);
//! [tutorial_read_dataset]
//! [tutorial_check_result]
double diff = norm(data - expected);
CV_Assert(abs(diff) < 1e-10);
//! [tutorial_check_result]
h5io->close();
}
static void write_single_channel()
{
String filename = "single_channel.h5";
String parent_name = "/data";
String dataset_name = parent_name + "/single";
// prepare data
Mat data;
data = (cv::Mat_<float>(2, 3) << 0, 1, 2, 3, 4, 5);
Ptr<hdf::HDF5> h5io = hdf::open(filename);
//! [tutorial_create_dataset]
// first we need to create the parent group
if (!h5io->hlexists(parent_name)) h5io->grcreate(parent_name);
// create the dataset if it not exists
if (!h5io->hlexists(dataset_name)) h5io->dscreate(data.rows, data.cols, data.type(), dataset_name);
//! [tutorial_create_dataset]
// the following is the same with the above function write_root_group_single_channel()
h5io->dswrite(data, dataset_name);
Mat expected;
h5io->dsread(expected, dataset_name);
double diff = norm(data - expected);
CV_Assert(abs(diff) < 1e-10);
h5io->close();
}
/*
* creating, reading and writing multiple-channel matrices
* are the same with single channel matrices
*/
static void write_multiple_channels()
{
String filename = "two_channels.h5";
String parent_name = "/data";
String dataset_name = parent_name + "/two_channels";
// prepare data
Mat data(2, 3, CV_32SC2);
for (size_t i = 0; i < data.total()*data.channels(); i++)
((int*) data.data)[i] = (int)i;
Ptr<hdf::HDF5> h5io = hdf::open(filename);
// first we need to create the parent group
if (!h5io->hlexists(parent_name)) h5io->grcreate(parent_name);
// create the dataset if it not exists
if (!h5io->hlexists(dataset_name)) h5io->dscreate(data.rows, data.cols, data.type(), dataset_name);
// the following is the same with the above function write_root_group_single_channel()
h5io->dswrite(data, dataset_name);
Mat expected;
h5io->dsread(expected, dataset_name);
double diff = norm(data - expected);
CV_Assert(abs(diff) < 1e-10);
h5io->close();
}
int main()
{
write_root_group_single_channel();
write_single_channel();
write_multiple_channels();
return 0;
}
//! [tutorial]