Classes | Public Member Functions | Protected Attributes | Private Types | Static Private Attributes
RandomSetter< SparseMatrixType, MapTraits, OuterPacketBits > Class Template Reference

The RandomSetter is a wrapper object allowing to set/update a sparse matrix with random access. More...

#include <RandomSetter.h>

List of all members.

Classes

struct  ScalarWrapper

Public Member Functions

Index nonZeros () const
Scalaroperator() (Index row, Index col)
 RandomSetter (SparseMatrixType &target)
 ~RandomSetter ()

Protected Attributes

HashMapTypem_hashmaps
unsigned char m_keyBitsOffset
Index m_outerPackets
SparseMatrixType * mp_target

Private Types

enum  {
  SwapStorage = 1 - MapTraits<ScalarWrapper>::IsSorted, TargetRowMajor = (SparseMatrixType::Flags & RowMajorBit) ? 1 : 0, SetterRowMajor = SwapStorage ? 1-TargetRowMajor : TargetRowMajor, IsUpper = SparseMatrixType::Flags & Upper,
  IsLower = SparseMatrixType::Flags & Lower
}
typedef MapTraits
< ScalarWrapper >::Type 
HashMapType
typedef SparseMatrixType::Index Index
typedef MapTraits
< ScalarWrapper >::KeyType 
KeyType
typedef SparseMatrixType::Scalar Scalar

Static Private Attributes

static const int OuterPacketMask = (1 << OuterPacketBits) - 1

Detailed Description

template<typename SparseMatrixType, template< typename T > class MapTraits = StdMapTraits, int OuterPacketBits = 6>
class RandomSetter< SparseMatrixType, MapTraits, OuterPacketBits >

The RandomSetter is a wrapper object allowing to set/update a sparse matrix with random access.

Parameters:
SparseMatrixTypethe type of the sparse matrix we are updating
MapTraitsa traits class representing the map implementation used for the temporary sparse storage. Its default value depends on the system.
OuterPacketBitsdefines the number of rows (or columns) manage by a single map object as a power of two exponent.

This class temporarily represents a sparse matrix object using a generic map implementation allowing for efficient random access. The conversion from the compressed representation to a hash_map object is performed in the RandomSetter constructor, while the sparse matrix is updated back at destruction time. This strategy suggest the use of nested blocks as in this example:

 SparseMatrix<double> m(rows,cols);
 {
   RandomSetter<SparseMatrix<double> > w(m);
   // don't use m but w instead with read/write random access to the coefficients:
   for(;;)
     w(rand(),rand()) = rand;
 }
 // when w is deleted, the data are copied back to m
 // and m is ready to use.

Since hash_map objects are not fully sorted, representing a full matrix as a single hash_map would involve a big and costly sort to update the compressed matrix back. To overcome this issue, a RandomSetter use multiple hash_map, each representing 2^OuterPacketBits columns or rows according to the storage order. To reach optimal performance, this value should be adjusted according to the average number of nonzeros per rows/columns.

The possible values for the template parameter MapTraits are:

The default map implementation depends on the availability, and the preferred order is: GoogleSparseHashMapTraits, GnuHashMapTraits, and finally StdMapTraits.

For performance and memory consumption reasons it is highly recommended to use one of the Google's hash_map implementation. To enable the support for them, you have two options:

See also:
http://code.google.com/p/google-sparsehash/

Definition at line 167 of file RandomSetter.h.


Member Typedef Documentation

template<typename SparseMatrixType, template< typename T > class MapTraits = StdMapTraits, int OuterPacketBits = 6>
typedef MapTraits<ScalarWrapper>::Type RandomSetter< SparseMatrixType, MapTraits, OuterPacketBits >::HashMapType [private]

Definition at line 178 of file RandomSetter.h.

template<typename SparseMatrixType, template< typename T > class MapTraits = StdMapTraits, int OuterPacketBits = 6>
typedef SparseMatrixType::Index RandomSetter< SparseMatrixType, MapTraits, OuterPacketBits >::Index [private]

Definition at line 170 of file RandomSetter.h.

template<typename SparseMatrixType, template< typename T > class MapTraits = StdMapTraits, int OuterPacketBits = 6>
typedef MapTraits<ScalarWrapper>::KeyType RandomSetter< SparseMatrixType, MapTraits, OuterPacketBits >::KeyType [private]

Definition at line 177 of file RandomSetter.h.

template<typename SparseMatrixType, template< typename T > class MapTraits = StdMapTraits, int OuterPacketBits = 6>
typedef SparseMatrixType::Scalar RandomSetter< SparseMatrixType, MapTraits, OuterPacketBits >::Scalar [private]

Definition at line 169 of file RandomSetter.h.


Member Enumeration Documentation

template<typename SparseMatrixType, template< typename T > class MapTraits = StdMapTraits, int OuterPacketBits = 6>
anonymous enum [private]
Enumerator:
SwapStorage 
TargetRowMajor 
SetterRowMajor 
IsUpper 
IsLower 

Definition at line 180 of file RandomSetter.h.


Constructor & Destructor Documentation

template<typename SparseMatrixType, template< typename T > class MapTraits = StdMapTraits, int OuterPacketBits = 6>
RandomSetter< SparseMatrixType, MapTraits, OuterPacketBits >::RandomSetter ( SparseMatrixType &  target) [inline]

Constructs a random setter object from the sparse matrix target

Note that the initial value of target are imported. If you want to re-set a sparse matrix from scratch, then you must set it to zero first using the setZero() function.

Definition at line 196 of file RandomSetter.h.

template<typename SparseMatrixType, template< typename T > class MapTraits = StdMapTraits, int OuterPacketBits = 6>
RandomSetter< SparseMatrixType, MapTraits, OuterPacketBits >::~RandomSetter ( ) [inline]

Destructor updating back the sparse matrix target

Definition at line 224 of file RandomSetter.h.


Member Function Documentation

template<typename SparseMatrixType, template< typename T > class MapTraits = StdMapTraits, int OuterPacketBits = 6>
Index RandomSetter< SparseMatrixType, MapTraits, OuterPacketBits >::nonZeros ( ) const [inline]
Returns:
the number of non zero coefficients
Note:
According to the underlying map/hash_map implementation, this function might be quite expensive.

Definition at line 323 of file RandomSetter.h.

template<typename SparseMatrixType, template< typename T > class MapTraits = StdMapTraits, int OuterPacketBits = 6>
Scalar& RandomSetter< SparseMatrixType, MapTraits, OuterPacketBits >::operator() ( Index  row,
Index  col 
) [inline]
Returns:
a reference to the coefficient at given coordinates row, col

Definition at line 306 of file RandomSetter.h.


Member Data Documentation

template<typename SparseMatrixType, template< typename T > class MapTraits = StdMapTraits, int OuterPacketBits = 6>
HashMapType* RandomSetter< SparseMatrixType, MapTraits, OuterPacketBits >::m_hashmaps [protected]

Definition at line 334 of file RandomSetter.h.

template<typename SparseMatrixType, template< typename T > class MapTraits = StdMapTraits, int OuterPacketBits = 6>
unsigned char RandomSetter< SparseMatrixType, MapTraits, OuterPacketBits >::m_keyBitsOffset [protected]

Definition at line 337 of file RandomSetter.h.

template<typename SparseMatrixType, template< typename T > class MapTraits = StdMapTraits, int OuterPacketBits = 6>
Index RandomSetter< SparseMatrixType, MapTraits, OuterPacketBits >::m_outerPackets [protected]

Definition at line 336 of file RandomSetter.h.

template<typename SparseMatrixType, template< typename T > class MapTraits = StdMapTraits, int OuterPacketBits = 6>
SparseMatrixType* RandomSetter< SparseMatrixType, MapTraits, OuterPacketBits >::mp_target [protected]

Definition at line 335 of file RandomSetter.h.

template<typename SparseMatrixType, template< typename T > class MapTraits = StdMapTraits, int OuterPacketBits = 6>
const int RandomSetter< SparseMatrixType, MapTraits, OuterPacketBits >::OuterPacketMask = (1 << OuterPacketBits) - 1 [static, private]

Definition at line 179 of file RandomSetter.h.


The documentation for this class was generated from the following file:


libicr
Author(s): Robert Krug
autogenerated on Mon Jan 6 2014 11:34:24