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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 files COPYING and Copyright.html. COPYING can be found at the root *
* of the source code distribution tree; Copyright.html can be found at the *
* root level of an installed copy of the electronic HDF5 document set and *
* is linked from the top-level documents page. It can also be found at *
* http://hdfgroup.org/HDF5/doc/Copyright.html. 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.printError();
return -1;
}
// catch failure caused by the DataSet operations
catch(DataSetIException error)
{
error.printError();
return -1;
}
// catch failure caused by the DataSpace operations
catch(DataSpaceIException error)
{
error.printError();
return -1;
}
return 0; // successfully terminated
}
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