LoadPartial.cpp

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/** @example LoadPartial.cpp \n
 * \brief Load a part of a file \n
 * <b>To run</b>: LoadPartial [file] [tag_name] [val1] [val2] ...\n
 *
 * In this example, it is shown how to load only a part of one file; the file must be organized in
 * sets. (cherry-picking only the sets we want) The sets to load are identified by a tag name and
 * the tag values for the sets of interest. This procedure is used when reading in parallel, as
 * each processor will load only its part of the file, identified either by partition or by
 * material/block sets by default, this example will load parallel partition sets with values 1, 2,
 * and 5 from ../MeshFiles/unittest/64bricks_1khex.h5m The example will always write the output to a
 * file name part.h5m
 */
 
#include <iostream>
#include <vector>
 
// Include header for MOAB instance and tag conventions for
#include "moab/Core.hpp"
#include "MBTagConventions.hpp"
 
#define NTAGVALS 3
 
using namespace moab;
using namespace std;
 
// Function to parse input parameters
ErrorCode get_file_options( int argc, char** argv, string& filename, string& tagName, vector< int >& tagValues )
{
 // Get mesh filename
 if( argc > 1 )
 filename = string( argv[1] );
 else
 filename = string( MESH_DIR ) + string( "/64bricks_512hex_256part.h5m" );
 
 // Get tag selection options
 if( argc > 2 )
 tagName = string( argv[2] );
 else
 tagName = "USERTAG";
 
 if( argc > 3 )
 {
 tagValues.resize( argc - 3, 0 );
 for( int i = 3; i < argc; ++i )
 tagValues[i - 3] = atoi( argv[i] );
 }
 else
 {
 for( unsigned i = 0; i < tagValues.size(); ++i )
 tagValues[i] = 2 * i + 1;
 }
 
 if( argc > 1 && argc < 4 ) // print usage
 cout << " usage is " << argv[0] << " <file> <tag_name> <value1> <value2> .. \n";
 return MB_SUCCESS;
}
 
int main( int argc, char** argv )
{
 // Get MOAB instance
 Interface* mb = new( std::nothrow ) Core;
 if( NULL == mb ) return 1;
 
 std::string filename, tagname;
 vector< int > tagvals( NTAGVALS ); // Allocate for a maximum of 5 tag values
 ErrorCode rval = get_file_options( argc, argv, filename, tagname, tagvals );MB_CHK_ERR( rval );
 
#ifdef MOAB_HAVE_HDF5
 // This file is in the mesh files directory
 rval = mb->load_file( filename.c_str(), 0, 0, PARALLEL_PARTITION_TAG_NAME, tagvals.data(), (int)tagvals.size() );MB_CHK_SET_ERR( rval, "Failed to read" );
 
 // If HANDLEID tag present, convert to long, and see what we read from file
 Tag handleid_tag;
 rval = mb->tag_get_handle( "HANDLEID", handleid_tag );
 if( MB_SUCCESS == rval )
 {
 // Convert a few values for a few vertices
 Range verts;
 rval = mb->get_entities_by_type( 0, MBVERTEX, verts );MB_CHK_SET_ERR( rval, "Failed to get vertices" );
 vector< long > valsTag( verts.size() );
 rval = mb->tag_get_data( handleid_tag, verts, &valsTag[0] );
 if( MB_SUCCESS == rval ) cout << "First 2 long values recovered: " << valsTag[0] << " " << valsTag[1] << "\n";
 }
 
 rval = mb->write_file( "part.h5m" );MB_CHK_SET_ERR( rval, "Failed to write partial file" );
 cout << "Wrote successfully part.h5m.\n";
 
#else
 std::cout << "Configure MOAB with HDF5 to build and use this example correctly.\n";
#endif
 delete mb;
 return 0;
}