HDF5 C++ API  1.8.20
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extend_ds.cpp
This example shows how to work with extendible datasets.
/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
* 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://support.hdfgroup.org/ftp/HDF5/releases. *
* If you do not have access to either file, you may request a copy from *
* help@hdfgroup.org. *
* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/*
* This example shows how to work with extendible dataset.
* In the current version of the library dataset MUST be
* chunked.
*
*/
#ifdef OLD_HEADER_FILENAME
#include <iostream.h>
#else
#include <iostream>
#endif
#include <string>
#ifndef H5_NO_NAMESPACE
#ifndef H5_NO_STD
using std::cout;
using std::endl;
#endif // H5_NO_STD
#endif
#include "H5Cpp.h"
#ifndef H5_NO_NAMESPACE
using namespace H5;
#endif
const H5std_string FILE_NAME( "SDSextendible.h5" );
const H5std_string DATASET_NAME( "ExtendibleArray" );
const int NX = 10;
const int NY = 5;
const int RANK = 2;
int main (void)
{
/*
* 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
*/
/*
* Create the data space with unlimited dimensions.
*/
hsize_t dims[2] = { 3, 3}; // dataset dimensions at creation
hsize_t maxdims[2] = {H5S_UNLIMITED, H5S_UNLIMITED};
DataSpace mspace1( RANK, dims, maxdims);
/*
* Create a new file. If file exists its contents will be overwritten.
*/
H5File file( FILE_NAME, H5F_ACC_TRUNC );
/*
* Modify dataset creation properties, i.e. enable chunking.
*/
hsize_t chunk_dims[2] ={2, 5};
cparms.setChunk( RANK, chunk_dims );
/*
* Set fill value for the dataset
*/
int fill_val = 0;
cparms.setFillValue( PredType::NATIVE_INT, &fill_val);
/*
* Create a new dataset within the file using cparms
* creation properties.
*/
DataSet dataset = file.createDataSet( DATASET_NAME, PredType::NATIVE_INT, mspace1, cparms);
/*
* Extend the dataset. This call assures that dataset is at least 3 x 3.
*/
hsize_t size[2];
size[0] = 3;
size[1] = 3;
dataset.extend( size );
/*
* Select a hyperslab.
*/
DataSpace fspace1 = dataset.getSpace ();
hsize_t offset[2];
offset[0] = 0;
offset[1] = 0;
hsize_t dims1[2] = { 3, 3}; /* data1 dimensions */
fspace1.selectHyperslab( H5S_SELECT_SET, dims1, offset );
/*
* Write the data to the hyperslab.
*/
int data1[3][3] = { {1, 1, 1}, /* data to write */
{1, 1, 1},
{1, 1, 1} };
dataset.write( data1, PredType::NATIVE_INT, mspace1, fspace1 );
/*
* Extend the dataset. Dataset becomes 10 x 3.
*/
hsize_t dims2[2] = { 7, 1}; /* data2 dimensions */
dims[0] = dims1[0] + dims2[0];
size[0] = dims[0];
size[1] = dims[1];
dataset.extend( size );
/*
* Select a hyperslab.
*/
DataSpace fspace2 = dataset.getSpace ();
offset[0] = 3;
offset[1] = 0;
fspace2.selectHyperslab( H5S_SELECT_SET, dims2, offset );
/*
* Define memory space
*/
DataSpace mspace2( RANK, dims2 );
/*
* Write the data to the hyperslab.
*/
int data2[7] = { 2, 2, 2, 2, 2, 2, 2};
dataset.write( data2, PredType::NATIVE_INT, mspace2, fspace2 );
/*
* Extend the dataset. Dataset becomes 10 x 5.
*/
hsize_t dims3[2] = { 2, 2}; /* data3 dimensions */
dims[1] = dims1[1] + dims3[1];
size[0] = dims[0];
size[1] = dims[1];
dataset.extend( size );
/*
* Select a hyperslab
*/
DataSpace fspace3 = dataset.getSpace ();
offset[0] = 0;
offset[1] = 3;
fspace3.selectHyperslab( H5S_SELECT_SET, dims3, offset );
/*
* Define memory space.
*/
DataSpace mspace3( RANK, dims3 );
/*
* Write the data to the hyperslab.
*/
int data3[2][2] = { {3, 3}, {3, 3} };
dataset.write( data3, PredType::NATIVE_INT, mspace3, fspace3 );
/*
* Read the data from this dataset and display it.
*/
int i, j;
int data_out[NX][NY];
for (i = 0; i < NX; i++)
{
for (j = 0; j < NY; j++)
data_out[i][j] = 0;
}
dataset.read( data_out, PredType::NATIVE_INT );
/*
* Resulting dataset
*
* 1 1 1 3 3
* 1 1 1 3 3
* 1 1 1 0 0
* 2 0 0 0 0
* 2 0 0 0 0
* 2 0 0 0 0
* 2 0 0 0 0
* 2 0 0 0 0
* 2 0 0 0 0
* 2 0 0 0 0
*/
/*
* Display the result.
*/
for (i=0; i < NX; i++)
{
for(j=0; j < NY; j++)
cout << data_out[i][j] << " ";
cout << endl;
}
} // 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;
}
// catch failure caused by the DataSpace operations
catch( DataTypeIException error )
{
error.printError();
return -1;
}
return 0;
}


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