knncolle::DistanceMetric< Data_, Distance_ > Class Template Reference

Interface for a distance metric. More...

#include <distances.hpp>

Inheritance diagram for knncolle::DistanceMetric< Data_, Distance_ >:

Public Member Functions
virtual Distance_	raw (std::size_t num_dimensions, const Data_ *x, const Data_ *y) const =0
virtual Distance_	normalize (Distance_ raw) const =0
virtual Distance_	denormalize (Distance_ norm) const =0

Detailed Description

template<typename Data_, typename Distance_>
class knncolle::DistanceMetric< Data_, Distance_ >

Interface for a distance metric.

Template Parameters

Distance_	Floating-point type for the output distance.
Data_	Numeric type for the input data.

Member Function Documentation

denormalize()

template<typename Data_ , typename Distance_ >

virtual Distance_ knncolle::DistanceMetric< Data_, Distance_ >::denormalize ( Distance_ norm ) const

pure virtual

Parameters

norm	Normalized distance (i.e., the output of normalize()).

Returns

The denormalized distance (i.e., the input to normalize()).

normalize()

template<typename Data_ , typename Distance_ >

virtual Distance_ knncolle::DistanceMetric< Data_, Distance_ >::normalize ( Distance_ raw ) const

pure virtual

Parameters

raw	Raw distance.

Returns

The normalized distance.

raw()

template<typename Data_ , typename Distance_ >

virtual Distance_ knncolle::DistanceMetric< Data_, Distance_ >::raw ( std::size_t num_dimensions, const Data_ * x, const Data_ * y ) const

pure virtual

The raw distance r for a distance d is defined so that r(x, y) > r(x, z) iff d(x, y) > d(x, z). r(x, y) is converted to d(x, z) via a monotonic transform in normalize(), and vice versa for denormalize(). We separate out these two steps to avoid, e.g., a costly root operation for a Euclidean distance when only the relative values are of interest.

Parameters

x	Pointer to the array containing the first vector.
y	Pointer to the array containing the second vector.
num_dimensions	Length of both vectors.

Returns

The raw distance between x and y.

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

• knncolle/distances.hpp