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/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* Copyright by The HDF Group. *
* Copyright by the Board of Trustees of the University of Illinois. *
* All rights reserved. *
* *
* This file is part of HDF5. The full HDF5 copyright notice, including *
* terms governing use, modification, and redistribution, is contained in *
* the COPYING file, which can be found at the root of the source code *
* distribution tree, or in https://www.hdfgroup.org/licenses. *
* If you do not have access to either file, you may request a copy from *
* help@hdfgroup.org. *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/*
* This example illustrates how to create a compressed dataset.
* It is used in the HDF5 Tutorial.
*/
#include <iostream>
using std::cout;
using std::endl;
#include <string>
#include "H5Cpp.h"
using namespace H5;
const H5std_string FILE_NAME("h5tutr_cmprss.h5");
const H5std_string DATASET_NAME("Compressed_Data");
const int DIM0 = 100;
const int DIM1 = 20;
int
main(void)
{
hsize_t dims[2] = {DIM0, DIM1}; // dataset dimensions
hsize_t chunk_dims[2] = {20, 20}; // chunk dimensions
int i, j, buf[DIM0][DIM1];
// Try block to detect exceptions raised by any of the calls inside it
try {
// Turn off the auto-printing when failure occurs so that we can
// handle the errors appropriately
Exception::dontPrint();
// Create a new file using the default property lists.
H5File file(FILE_NAME, H5F_ACC_TRUNC);
// Create the data space for the dataset.
DataSpace *dataspace = new DataSpace(2, dims);
// Modify dataset creation property to enable chunking
DSetCreatPropList *plist = new DSetCreatPropList;
plist->setChunk(2, chunk_dims);
// Set ZLIB (DEFLATE) Compression using level 6.
// To use SZIP compression comment out this line.
plist->setDeflate(6);
// Uncomment these lines to set SZIP Compression
// unsigned szip_options_mask = H5_SZIP_NN_OPTION_MASK;
// unsigned szip_pixels_per_block = 16;
// plist->setSzip(szip_options_mask, szip_pixels_per_block);
// Create the dataset.
DataSet *dataset =
new DataSet(file.createDataSet(DATASET_NAME, PredType::STD_I32BE, *dataspace, *plist));
for (i = 0; i < DIM0; i++)
for (j = 0; j < DIM1; j++)
buf[i][j] = i + j;
// Write data to dataset.
dataset->write(buf, PredType::NATIVE_INT);
// Close objects and file. Either approach will close the HDF5 item.
delete dataspace;
delete dataset;
delete plist;
file.close();
// -----------------------------------------------
// Re-open the file and dataset, retrieve filter
// information for dataset and read the data back.
// -----------------------------------------------
int rbuf[DIM0][DIM1];
int numfilt;
size_t nelmts = {1}, namelen = {1};
unsigned flags, filter_info, cd_values[1], idx;
char name[1];
H5Z_filter_t filter_type;
// Open the file and the dataset in the file.
file.openFile(FILE_NAME, H5F_ACC_RDONLY);
dataset = new DataSet(file.openDataSet(DATASET_NAME));
// Get the create property list of the dataset.
plist = new DSetCreatPropList(dataset->getCreatePlist());
// Get the number of filters associated with the dataset.
numfilt = plist->getNfilters();
cout << "Number of filters associated with dataset: " << numfilt << endl;
for (idx = 0; idx < numfilt; idx++) {
nelmts = 0;
filter_type = plist->getFilter(idx, flags, nelmts, cd_values, namelen, name, filter_info);
cout << "Filter Type: ";
switch (filter_type) {
case H5Z_FILTER_DEFLATE:
cout << "H5Z_FILTER_DEFLATE" << endl;
break;
case H5Z_FILTER_SZIP:
cout << "H5Z_FILTER_SZIP" << endl;
break;
default:
cout << "Other filter type included." << endl;
}
}
// Read data.
dataset->read(rbuf, PredType::NATIVE_INT);
delete plist;
delete dataset;
file.close(); // can be skipped
} // end of try block
// catch failure caused by the H5File operations
catch (FileIException error) {
error.printErrorStack();
return -1;
}
// catch failure caused by the DataSet operations
catch (DataSetIException error) {
error.printErrorStack();
return -1;
}
// catch failure caused by the DataSpace operations
catch (DataSpaceIException error) {
error.printErrorStack();
return -1;
}
return 0; // successfully terminated
}
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