This utility class provides a convenient implementation for building the compressed-row-storage graph required for the METIS/ParMETIS graph partitioning schemes. More...

#include <metis_csr_graph.h>

Public Member Functions
void	prep_n_nonzeros (const libMesh::dof_id_type row, const libMesh::dof_id_type n_nonzeros_in)
	Sets the number of non-zero values in the given row. More...

libMesh::dof_id_type	n_nonzeros (const libMesh::dof_id_type row) const

void	prepare_for_use ()
	Replaces the entries in the offsets vector with their partial sums and resizes the val vector accordingly. More...

IndexType &	operator() (const libMesh::dof_id_type row, const libMesh::dof_id_type nonzero)

const IndexType &	operator() (const libMesh::dof_id_type row, const libMesh::dof_id_type nonzero) const

Public Attributes
std::vector< IndexType >	offsets

std::vector< IndexType >	vals

Detailed Description

template<class IndexType>
class libMesh::METIS_CSR_Graph< IndexType >

This utility class provides a convenient implementation for building the compressed-row-storage graph required for the METIS/ParMETIS graph partitioning schemes.

Author: Benjamin S. Kirk

Date: 2013

Compressed graph data structure used by MetisPartitioner.

Definition at line 43 of file metis_csr_graph.h.

Member Function Documentation

◆ n_nonzeros()

template<class IndexType>

libMesh::dof_id_type libMesh::METIS_CSR_Graph< IndexType >::n_nonzeros ( const libMesh::dof_id_type row ) const

inline

Returns: The number of nonzeros in the requested row by subtracting the offsets vector entries.

Definition at line 63 of file metis_csr_graph.h.

   {
     libmesh_assert_less (row+1, offsets.size());
     return (offsets[row+1] - offsets[row]);
   }

References libMesh::METIS_CSR_Graph< IndexType >::offsets.

◆ operator()() [1/2]

template<class IndexType>

IndexType& libMesh::METIS_CSR_Graph< IndexType >::operator()	(	const libMesh::dof_id_type	row,
		const libMesh::dof_id_type	nonzero
	)

inline

Returns: A writable reference to the nonzero'th entry of row.

Definition at line 86 of file metis_csr_graph.h.

   {
     libmesh_assert_greater (vals.size(), offsets[row]+nonzero);
  
     return vals[offsets[row]+nonzero];
   }

References libMesh::METIS_CSR_Graph< IndexType >::offsets, and libMesh::METIS_CSR_Graph< IndexType >::vals.

◆ operator()() [2/2]

template<class IndexType>

const IndexType& libMesh::METIS_CSR_Graph< IndexType >::operator()	(	const libMesh::dof_id_type	row,
		const libMesh::dof_id_type	nonzero
	)		const

inline

Returns: A const reference to the nonzero'th entry of row.

Definition at line 97 of file metis_csr_graph.h.

   {
     libmesh_assert_greater (vals.size(), offsets[row]+nonzero);
  
     return vals[offsets[row]+nonzero];
   }

References libMesh::METIS_CSR_Graph< IndexType >::offsets, and libMesh::METIS_CSR_Graph< IndexType >::vals.

◆ prep_n_nonzeros()

template<class IndexType>

void libMesh::METIS_CSR_Graph< IndexType >::prep_n_nonzeros	(	const libMesh::dof_id_type	row,
		const libMesh::dof_id_type	n_nonzeros_in
	)

inline

Sets the number of non-zero values in the given row.

The internal indexing is 1-based.

Definition at line 52 of file metis_csr_graph.h.

   {
     libmesh_assert_less (row+1, offsets.size());
     offsets[row+1] = n_nonzeros_in;
   }

References libMesh::METIS_CSR_Graph< IndexType >::offsets.

Referenced by libMesh::MetisPartitioner::partition_range().

◆ prepare_for_use()

template<class IndexType>

void libMesh::METIS_CSR_Graph< IndexType >::prepare_for_use ( )

inline

Replaces the entries in the offsets vector with their partial sums and resizes the val vector accordingly.

Definition at line 73 of file metis_csr_graph.h.

   {
     std::partial_sum (offsets.begin(), offsets.end(), offsets.begin());
     libmesh_assert (!offsets.empty());
     vals.resize(offsets.back());
  
     if (vals.empty())
       vals.push_back(0);
   }