geo::vect::MiddlePointAccumulatorDim< N > Class Template Reference

Helper class to compute the middle point in a point set. More...

#include "geo_vectors_utils.h"

Public Member Functions
	MiddlePointAccumulatorDim ()
	Default constructor: starts with no accumulated point. More...
template<typename BeginIter , typename EndIter >
	MiddlePointAccumulatorDim (BeginIter begin, EndIter end)
	Constructor: starts with accumulating a sequence of points. More...
Result query
bool	empty () const
	Returns whether the total weight is zero (usually means no points). More...
double	weight () const
	Returns the total weight (number of points if all have weight 1). More...
template<typename Point >
Point	middlePointAs () const
	Returns the middle point, NaN components if no point. More...
geo::Point_t	middlePoint () const
Addition of points
template<typename Point >
void	add (Point const &p)
	Accumulates a point. More...
template<typename Point >
void	add (Point const &p, double weight)
	Accumulates a point. More...
template<typename BeginIter , typename EndIter >
void	add (BeginIter begin, EndIter end)
	Adds a sequence of points. More...
void	clear ()
	Resets the status of the object to no accumulated points. More...

Private Types
using	IndexSequence_t = std::make_index_sequence< Dim >

Private Member Functions
template<typename Point , std::size_t... I>
Point	makePointImpl (std::index_sequence< I... >) const
template<typename Point , std::size_t... I>
Point	makeWeightedPointImpl (double w, std::index_sequence< I... >) const
template<typename Point >
Point	makePoint () const
	Converts the internal sums into a Point. More...
template<typename Point >
Point	makeWeightedPoint (double w) const

Private Attributes
std::array< Length_t, Dim >	fSums
	Sum of each of the point components. More...
double	fW = 0.0
	Total weight. More...

Static Private Attributes
static constexpr unsigned int	Dim = N
	Dimension of the points. More...

Detailed Description

template<unsigned int N = 3U>
class geo::vect::MiddlePointAccumulatorDim< N >

Helper class to compute the middle point in a point set.

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Template Parameters

N	_(default: 3)_ dimension of the points

This class accumulates cartesian points and returns their middle point when asked.

In the following example, only the points from a list (points) which have y coordinate larger than 0 are averaged, all with the same weight:

std::array<geo::Point_t, 4> const points = {
  geo::Point_t{ 0.0,  1.0,  2.0 },
  geo::Point_t{ 0.0, -1.0,  2.0 },
  geo::Point_t{ 0.0,  1.0, -2.0 },
  geo::Point_t{ 0.0, -1.0, -2.0 }
};

geo::vect::MiddlePointAccumulatorDim pointsAboveGround;
for (auto const& point: points)
  if (point.Y() > 0.0) pointsAboveGround.add(point);

if (pointsAboveGround.empty())
  throw std::runtime_error("No point above ground!");

auto middleAboveGround = pointsAboveGround.middlePoint();

Note the check to make sure that there are points that fulfil the requirement.

Definition at line 1333 of file geo_vectors_utils.h.

Member Typedef Documentation

template<unsigned int N = 3U>

using geo::vect::MiddlePointAccumulatorDim< N >::IndexSequence_t = std::make_index_sequence<Dim>

private

Definition at line 1452 of file geo_vectors_utils.h.

Constructor & Destructor Documentation

template<unsigned int N = 3U>

geo::vect::MiddlePointAccumulatorDim< N >::MiddlePointAccumulatorDim ( )

inline

Default constructor: starts with no accumulated point.

Definition at line 1340 of file geo_vectors_utils.h.

{ fSums.fill(0.); }

template<unsigned int N = 3U>

template<typename BeginIter , typename EndIter >

geo::vect::MiddlePointAccumulatorDim< N >::MiddlePointAccumulatorDim ( BeginIter  begin, EndIter  end  )

inline

Constructor: starts with accumulating a sequence of points.

Template Parameters

BeginIter	type of iterator to a point type compatible with add()
EndIter	type of end iterator

Parameters

begin	iterator to the first point to be added
end	iterator after the last point to be added

See also

add()

Definition at line 1351 of file geo_vectors_utils.h.

                                                              : MiddlePointAccumulatorDim()
      {
        add(begin, end);
      }

Member Function Documentation

template<unsigned int N = 3U>

template<typename Point >

void geo::vect::MiddlePointAccumulatorDim< N >::add ( Point const &  p )

inline

Accumulates a point.

Template Parameters

Point

point type, required to have X(), Y() and Z() accessors

Parameters

p	point to be included

The point is added with weight 1.

Definition at line 1403 of file geo_vectors_utils.h.

References geo::vect::bindCoordManagers().

Referenced by trkf::TrajectoryMCSFitter::linearRegression().

      {
        std::size_t ic = 0U;
        for (auto c : geo::vect::bindCoordManagers(p))
          fSums[ic++] += c();
        fW += 1.0;
      }

template<unsigned int N = 3U>

template<typename Point >

void geo::vect::MiddlePointAccumulatorDim< N >::add ( Point const &  p, double  weight  )

inline

Accumulates a point.

Template Parameters

Point

point type, required to have X(), Y() and Z() accessors

Parameters

p	point to be included
weight	the relative weight of this point

Definition at line 1418 of file geo_vectors_utils.h.

References geo::vect::bindCoordManagers(), and weight.

      {
        std::size_t ic = 0U;
        for (auto c : geo::vect::bindCoordManagers(p))
          fSums[ic++] += weight * c();
        fW += weight;
      }

template<unsigned int N = 3U>

template<typename BeginIter , typename EndIter >

void geo::vect::MiddlePointAccumulatorDim< N >::add ( BeginIter  begin, EndIter  end  )

inline

Adds a sequence of points.

Template Parameters

BeginIter	type of iterator to a point type compatible with add()
EndIter	type of end iterator

Parameters

begin	iterator to the first point to be added
end	iterator after the last point to be added

Each point is added with weight 1.0.

Definition at line 1436 of file geo_vectors_utils.h.

      {
        std::for_each(begin, end, [this](auto const& p) { this->add(p); });
      }

template<unsigned int N = 3U>

void geo::vect::MiddlePointAccumulatorDim< N >::clear ( )

inline

Resets the status of the object to no accumulated points.

Definition at line 1442 of file geo_vectors_utils.h.

      {
        fSums.fill(0.);
        fW = 0.0;
      }

template<unsigned int N = 3U>

bool geo::vect::MiddlePointAccumulatorDim< N >::empty ( ) const

inline

Returns whether the total weight is zero (usually means no points).

Definition at line 1361 of file geo_vectors_utils.h.

{ return fW == 0.0; }

template<unsigned int N = 3U>

template<typename Point >

Point geo::vect::MiddlePointAccumulatorDim< N >::makePoint ( ) const

inlineprivate

Converts the internal sums into a Point.

Definition at line 1468 of file geo_vectors_utils.h.

      {
        return geo::vect::makeFromCoords<Point>(fSums);
      }

template<unsigned int N = 3U>

template<typename Point , std::size_t... I>

Point geo::vect::MiddlePointAccumulatorDim< N >::makePointImpl ( std::index_sequence< I... >  ) const

inlineprivate

Definition at line 1455 of file geo_vectors_utils.h.

      {
        return {fSums.operator[](I)...};
      }

template<unsigned int N = 3U>

template<typename Point >

Point geo::vect::MiddlePointAccumulatorDim< N >::makeWeightedPoint ( double  w ) const

inlineprivate

Converts the internal sums into a Point with components scaled by w.

Definition at line 1476 of file geo_vectors_utils.h.

References w.

      {
        return makeWeightedPointImpl<Point>(w, IndexSequence_t{});
      }

template<unsigned int N = 3U>

template<typename Point , std::size_t... I>

Point geo::vect::MiddlePointAccumulatorDim< N >::makeWeightedPointImpl ( double  w, std::index_sequence< I... >    ) const

inlineprivate

Definition at line 1461 of file geo_vectors_utils.h.

      {
        return {(fSums.operator[](I) * w)...};
      }

template<unsigned int N = 3U>

geo::Point_t geo::vect::MiddlePointAccumulatorDim< N >::middlePoint ( ) const

inline

Returns the middle point as a geo::Point_t, NaN components if no point.

Definition at line 1386 of file geo_vectors_utils.h.

Referenced by trkf::TrajectoryMCSFitter::linearRegression().

{ return middlePointAs<geo::Point_t>(); }

template<unsigned int N = 3U>

template<typename Point >

Point geo::vect::MiddlePointAccumulatorDim< N >::middlePointAs ( ) const

inline

Returns the middle point, NaN components if no point.

Template Parameters

Point

type of the output point

The type of return point must be specified as template argument, e.g.

auto mp = accumulator.middlePointAs<TVector3>();

The Point type is required to have a constructor with the three cartesian components as arguments.

Definition at line 1378 of file geo_vectors_utils.h.

      {
        return makeWeightedPoint<Point>(1.0 / fW);
      }

template<unsigned int N = 3U>

double geo::vect::MiddlePointAccumulatorDim< N >::weight ( ) const

inline

Returns the total weight (number of points if all have weight 1).

Definition at line 1364 of file geo_vectors_utils.h.

{ return fW; }

Member Data Documentation

template<unsigned int N = 3U>

constexpr unsigned int geo::vect::MiddlePointAccumulatorDim< N >::Dim = N

staticprivate

Dimension of the points.

Definition at line 1334 of file geo_vectors_utils.h.

template<unsigned int N = 3U>

std::array<Length_t, Dim> geo::vect::MiddlePointAccumulatorDim< N >::fSums

private

Sum of each of the point components.

Definition at line 1335 of file geo_vectors_utils.h.

template<unsigned int N = 3U>

double geo::vect::MiddlePointAccumulatorDim< N >::fW = 0.0

private

Total weight.

Definition at line 1336 of file geo_vectors_utils.h.

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

• larcorealg/v09_13_01/source/larcorealg/Geometry/geo_vectors_utils.h