drwnSparseVec< T > Class Template Reference

Quick-and-dirty sparse vector class as a plugin replacement for std::vector. More...

Classes
class	iterator
class	reference

Public Types
typedef T	value_type
typedef T *	pointer
typedef const T *	const_pointer
typedef const T &	const_reference
typedef size_t	size_type
typedef ptrdiff_t	difference_type

Public Member Functions
	drwnSparseVec (size_t size)
	drwnSparseVec (const drwnSparseVec< T > &v)
	drwnSparseVec (const vector< T > &v)
bool	empty () const
void	clear ()
void	resize (size_t n)
size_t	size () const
size_t	capacity () const
size_t	max_size () const
void	reserve (size_t size)
void	swap (drwnSparseVec< T > &v)
size_t	nnz () const
iterator	begin ()
iterator	end ()
void	push_back (const T &x)
void	pop_back ()
void	insert (size_t position, const T &x)
void	insert (size_t position, typename vector< T >::const_iterator first, typename vector< T >::const_iterator last)
void	insert (iterator position, const T &x)
void	insert (iterator position, typename vector< T >::const_iterator first, typename vector< T >::const_iterator last)
drwnSparseVec &	operator= (const drwnSparseVec< T > &v)
drwnSparseVec &	operator= (const vector< T > &v)
const T &	operator[] (size_t indx) const
reference	operator[] (size_t indx)
	operator vector< T > () const

Static Public Member Functions
static T	dot (const vector< T > &x, const drwnSparseVec< T > &y)
	efficient dot product between a vector and a sparse vector
static T	dot (const drwnSparseVec< T > &x, const vector< T > &y)
	efficient dot product between a sparse vector and a vector
static T	dot (const drwnSparseVec< T > &x, const drwnSparseVec< T > &y)
	efficient dot product between two sparse vectors

Protected Member Functions
vector< T >	decode () const
void	encode (const vector< T > &v)

Protected Attributes
size_t	_size
map< size_t, T >	_data

Static Protected Attributes
static const T	_zero

Friends
class	reference
class	iterator

Detailed Description

template<typename T>
class drwnSparseVec< T >

Quick-and-dirty sparse vector class as a plugin replacement for std::vector.

The class has the same interface as std::vector, but does not explicitly store zeros. The class typecasts between std::vector objects when needed so is very computationally inefficient. However, code modification should be minimal. The dot product member function should be used where possible to mitigate computational inefficiency.

The folllowing code snippet demonstrates example usage:

drwnSparseVec<double> x(1000);
for (size_t i = 0; i < x.size(); i++) {
    if (drand48() < 0.1)
        x[i] = 1.0;
}

DRWN_LOG_MESSAGE("sparse vector has " << x.nnz() << " non-zero entries");

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

• drwnSparseVector.h