hdf5/c++/examples/readdata.cpp

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//  
//      This example reads hyperslab from the SDS.h5 file into
//      two-dimensional plane of a three-dimensional array.  Various 
//      information about the dataset in the SDS.h5 file is obtained. 
//

#include <string>

#ifdef OLD_HEADER_FILENAME
#include <iostream.h>
#else
#include <iostream>
#endif
#include "H5Cpp.h"

#ifndef H5_NO_NAMESPACE
using namespace H5;
#endif

const string FILE_NAME( "SDS.h5" );
const string DATASET_NAME( "IntArray" );
const int    NX_SUB = 3;	// hyperslab dimensions
const int    NY_SUB = 4;
const int    NX = 7;		// output buffer dimensions
const int    NY = 7;
const int    NZ = 3;
const int    RANK_OUT = 3;

int main (void)
{
   //
   // Output buffer initialization.
   //
   int i, j, k;
   int         data_out[NX][NY][NZ ]; /* output buffer */
   for (j = 0; j < NX; j++)
   {
      for (i = 0; i < NY; i++)
      {
 	 for (k = 0; k < NZ ; k++)
	    data_out[j][i][k] = 0;
      }
   } 

   // Try block to detect exceptions raised by any of the calls inside it
   try
   {
      //
      // Open the specified file and the specified dataset in the file.
      //
      H5File file( FILE_NAME, H5F_ACC_RDONLY );
      DataSet dataset = file.openDataSet( DATASET_NAME );

      // Get the class of the datatype that is used by the dataset.
      H5T_class_t type_class = dataset.getTypeClass();

      // Get class of datatype and print message if it's an integer.
      if( type_class == H5T_INTEGER )
      {
	 cout << "Data set has INTEGER type" << endl;

	 // Get the integer datatype
	 IntType intype = dataset.getIntType();

         // Get order of datatype and print message if it's a little endian.
	 string order_string;
         H5T_order_t order = intype.getOrder( order_string );
	 cout << order_string << endl;

         // Get size of the data element stored in file and print it.
         size_t size = intype.getSize();
         cout << "Data size is " << size << endl;
      }

      // Get dataspace of the dataset.
      DataSpace dataspace = dataset.getSpace();

      // Get the number of dimensions in the dataspace.
      int rank = dataspace.getSimpleExtentNdims();

      // Get the dimension size of each dimension in the dataspace and
      // display them.
      hsize_t dims_out[2];
      int ndims = dataspace.getSimpleExtentDims( dims_out, NULL);
      cout << "rank " << rank << ", dimensions " <<
	      (unsigned long)(dims_out[0]) << " x " <<
	      (unsigned long)(dims_out[1]) << endl;

      // Define hyperslab in the dataset; implicitly giving strike and 
      // block NULL.
      hssize_t     offset[2];	// hyperslab offset in the file
      hsize_t      count[2];	// size of the hyperslab in the file
      offset[0] = 1;
      offset[1] = 2;
      count[0]  = NX_SUB;
      count[1]  = NY_SUB;
      dataspace.selectHyperslab( H5S_SELECT_SET, count, offset );

      // Define the memory dataspace.
      hsize_t     dimsm[3];              /* memory space dimensions */
      dimsm[0] = NX;
      dimsm[1] = NY;
      dimsm[2] = NZ ;
      DataSpace memspace( RANK_OUT, dimsm );   

      // Define memory hyperslab. 
      hssize_t     offset_out[3];	// hyperslab offset in memory
      hsize_t      count_out[3];	// size of the hyperslab in memory
      offset_out[0] = 3;
      offset_out[1] = 0;
      offset_out[2] = 0;
      count_out[0]  = NX_SUB;
      count_out[1]  = NY_SUB;
      count_out[2]  = 1;
      memspace.selectHyperslab( H5S_SELECT_SET, count_out, offset_out );

      // Read data from hyperslab in the file into the hyperslab in 
      // memory and display the data.
      dataset.read( data_out, PredType::NATIVE_INT, memspace, dataspace );

      for (j = 0; j < NX; j++)
      {
	for (i = 0; i < NY; i++)
	   cout << data_out[j][i][0] << " ";
	cout << endl;
      }
      /*
       * 0 0 0 0 0 0 0
       * 0 0 0 0 0 0 0
       * 0 0 0 0 0 0 0
       * 3 4 5 6 0 0 0  
       * 4 5 6 7 0 0 0
       * 5 6 7 8 0 0 0
       * 0 0 0 0 0 0 0
       */
   }  // end of try block

   // catch failure caused by the H5File operations
   catch( FileIException error )
   {
      error.printError();
   }

   // catch failure caused by the DataSet operations
   catch( DataSetIException error )
   {
      error.printError();
   }

   // catch failure caused by the DataSpace operations
   catch( DataSpaceIException error )
   {
      error.printError();
   }

   // catch failure caused by the DataSpace operations
   catch( DataTypeIException error )
   {
      error.printError();
   }

   return 0;  // successfully terminated
}