lti::l2SquareDistantor< T, D > Class Template Reference

Policy class used by several classifiers/trees to measure the square of the euclidian distance between two points of type T. More...

#include <ltiL2Distance.h>

Inheritance diagram for lti::l2SquareDistantor< T, D >:

[legend]

List of all members.

Public Types
typedef D	distance_type
Public Member Functions
distance_type	operator() (const T &a, const T &b) const
Special methods for Minkowski distances
void	accumulate (const distance_type element, distance_type &accumulator) const
void	accumulate (const typename T::value_type element1, const typename T::value_type element2, distance_type &accumulator) const
distance_type	computeDistance (const distance_type &accumulator) const
distance_type	component (const typename T::value_type element1, const typename T::value_type element2) const
bool	accLessThan (const distance_type acc, const distance_type dist) const
bool	accGreaterThan (const distance_type acc, const distance_type dist) const

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Detailed Description

template<class T, class D = typename distanceType<T>::square_distance_type>
class lti::l2SquareDistantor< T, D >

Policy class used by several classifiers/trees to measure the square of the euclidian distance between two points of type T.

The type T MUST define the value_type type, which exist for example for vectors, (t)points and (t)rgbPixels.

If you really want, you can use this class directly through the operator().

 l2SquareDistantor< vector<double> > myDist;
 dvector a,b;
 ... // fill vectors with data
 double dist = myDist(a,b);

But remember that there is also a global template function distanceSqr() which is easier to use:

 dvector a,b;
 ... // fill vectors with data
 double dist = distanceSqr(a,b);

You can of course also use the lti::l2Distance functor, as usual with its apply() methods.

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Member Typedef Documentation

template<class T, class D = typename distanceType<T>::square_distance_type>

typedef D lti::l2SquareDistantor< T, D >::distance_type

type returned by the distantor

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Member Function Documentation

template<class T, class D = typename distanceType<T>::square_distance_type>

bool lti::l2SquareDistantor< T, D >::accGreaterThan	(	const distance_type	acc,
		const distance_type	dist
	)			const [inline]

Return true if the given partial computed from accumulator is greater than the given distance.

Assume you have accumulated acc until now, and you want to check if the partial distance derived from this accumulator is greater than the given distance. So you check accLessThan(accumulator,distance)

For this norm it computes acc > dist

template<class T, class D = typename distanceType<T>::square_distance_type>

bool lti::l2SquareDistantor< T, D >::accLessThan	(	const distance_type	acc,
		const distance_type	dist
	)			const [inline]

Return true if the given partial computed from accumulator is less than the given distance.

Assume you have accumulated acc until now, and you want to check if the partial distance derived from this accumulator is less than the given distance. So you check accLessThan(accumulator,distance)

For this norm it computes acc < dist

template<class T, class D = typename distanceType<T>::square_distance_type>

void lti::l2SquareDistantor< T, D >::accumulate	(	const typename T::value_type	element1,
		const typename T::value_type	element2,
		distance_type &	accumulator
	)			const [inline]

This member accumulates in the given accumulator, the difference of the given elements.

It can be used when the distance need to be computed manually, but using a distantor to still allow the flexibility of changing distances.

For the l2SquareDistantor this is just acc+=((elem1-elem2)^2).

Parameters:

	element1	component of the first point
	element2	component of the second point
	accumulator	variable where the elements will be accumulated.

template<class T, class D = typename distanceType<T>::square_distance_type>

void lti::l2SquareDistantor< T, D >::accumulate	(	const distance_type	element,
		distance_type &	accumulator
	)			const [inline]

This member accumulates in the given accumulator, the given element.

It can be used when the distance need to be computed manually, but using a distantor to still allow the flexibility of changing distances.

For the l2SquareDistantor this is just acc+=(elem*elem).

Parameters:

	element	component of the difference between two points.
	accumulator	variable where the elements will be accumulated.

template<class T, class D = typename distanceType<T>::square_distance_type>

distance_type lti::l2SquareDistantor< T, D >::component	(	const typename T::value_type	element1,
		const typename T::value_type	element2
	)			const [inline]

return the distance between two components, which is in some way a component of the total distance (that is the reason for the name).

For this distantor it return (element2-element1)^2

template<class T, class D = typename distanceType<T>::square_distance_type>

distance_type lti::l2SquareDistantor< T, D >::computeDistance

(

const distance_type &

accumulator

)

const [inline]

Compute from the given accumulator the desired distance.

template<class T, class D = typename distanceType<T>::square_distance_type>

distance_type lti::l2SquareDistantor< T, D >::operator()	(	const T &	a,
		const T &	b
	)			const [inline]

compute the distance between a and b

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

• ltiL2Distance.h