Database join on matrix columns. More...

#include <vnl_scalar_join_iterator.h>

Public Member Functions
	vnl_scalar_join_iterator (const vnl_matrix< T > &relation1, unsigned column1, const vnl_matrix< T > &relation2, unsigned column2)
	Initialize this iterator to the join of relation1(:,column1) and relation2(:,column2).
	~vnl_scalar_join_iterator ()
	Destructor.
	operator safe_bool () const
	Return true if all pairs have been seen.
bool	operator! () const
	Return false if all pairs have been seen.
vnl_scalar_join_iterator< T > &	operator++ ()
	Advance to the next pair. This is prefix ++.
bool	done () const
void	next ()
	Increment the iterator to point to the next pair of rows.
unsigned	row1 () const
	Return the index of the current row in the first relation.
unsigned	row2 () const
	Return the index of the current row in the second relation.
Protected Attributes
unsigned	n1
unsigned	n2
vcl_list < vnl_scalar_join_iterator_indexed_pair < T > > *	pI1
vcl_list < vnl_scalar_join_iterator_indexed_pair < T > > *	pI2
vcl_list < vnl_scalar_join_iterator_indexed_pair < T > > &	I1
vcl_list < vnl_scalar_join_iterator_indexed_pair < T > > &	I2
vcl_list < vnl_scalar_join_iterator_indexed_pair < T > >::iterator	index1
vcl_list < vnl_scalar_join_iterator_indexed_pair < T > >::iterator	index2
Private Member Functions
vnl_scalar_join_iterator< T >	operator++ (int)
	Postfix ++ should not be used. Only present for instantiation purposes.
Private Attributes
	VCL_SAFE_BOOL_DEFINE

Detailed Description

template<class T>
class vnl_scalar_join_iterator< T >

Database join on matrix columns.

vnl_scalar_join_iterator implements a fast database join on columns of matrices of scalars. "Scalar" here really means that the objects have comparison operators. The cost is O(n log n) where n is the number of rows, all for the two sorts in the ctor.

CAVEAT: The current implementation fudges multiple occurrences of the same key in the source column. For example,

    join  1 3 and  3 5 on columns 2 and 1 respectively
          2 3      3 6

should give

and it doesn't. Contact awf if you need this to work.

Definition at line 68 of file vnl_scalar_join_iterator.h.

Constructor & Destructor Documentation

template<class T >

vnl_scalar_join_iterator< T >::vnl_scalar_join_iterator	(	const vnl_matrix< T > &	relation1,
		unsigned	column1,
		const vnl_matrix< T > &	relation2,
		unsigned	column2
	)

Initialize this iterator to the join of relation1(:,column1) and relation2(:,column2).

The algorithm sorts an array of pointers to each row and traversal of the iterator runs through these to produce the join. After construction the row1() and row2() methods indicate the first pair.

Definition at line 49 of file vnl_scalar_join_iterator.txx.

template<class T >

vnl_scalar_join_iterator< T >::~vnl_scalar_join_iterator ( )

Destructor.

Definition at line 90 of file vnl_scalar_join_iterator.txx.