JetGeom Namespace Reference

A collection of routines for geometric tasks in 2D and on a cylinder. More...

Classes
class	line_t
	oriented segment/line in a simplistic way More...
class	point_set_t
class	point_t
	Very basic point objects. More...
class	point_vect_t

Typedefs
typedef std::list< point_t >	point_list_t

Functions
template<class inT, class ouT>
void	findConvexHull (inT &inSet, ouT &outSet)
	Find convex hull of a set of points in euclidian plan.
template<class ouT>
void	findConvexHull (point_set_t &inSet, ouT &outSet)
	specialization for point_set_t
template<class inT>
void	_findConvexHull (point_set_t &inSet, inT &outSet)
void	testHullLine (point_list_t &hull, point_t p)
template<class T>
float	polygon_area (T &line)
template<class T>
float	polygon_lenght (T &line)
template<class T>
float	getMeanPhi (T &set)
	return average phi (i.e.
template<class T>
float	max_deltaR (point_t p, T &set)
	Return max distance betweens point.
template<class T, class T2>
void	recenter_set (T &inSet, T2 &outSet, float phicenter)
	copy
template<class T, class T2>
void	recenter_set (T &inSet, T2 &outSet)
	copy
float	in_mPI_pPI (float phi)
	convert
void	fix2pi (point_t &p)
	convert
float	deltaR (point_t &p1, point_t &p2)
	distances between points
float	deltaR2 (point_t &p1, point_t &p2)
float	deltaPhi (point_t &p1, point_t &p2)
float	deltaPhi (float phi1, float phi2)
void	listToSet (point_list_t &inList, point_set_t &outSet)
template<class T>
void	clear_delete (T &container)
template<class T>
void	delete_content (T &container)
float	abs_dphi (float phi1, float phi2)
point_t	recenter (const point_t &p, const point_t &center)
point_t	recenter (const point_t &p, float phicenter)
template<class T>
void	_findConvexHull (point_set_t &inSet, T &outSet)

Detailed Description

A collection of routines for geometric tasks in 2D and on a cylinder.

Including a convex hull finder.

Author

P.A. Delsart

Date

(first implementation) June , 2007

Typedef Documentation

point_list_t

typedef std::list<point_t> JetGeom::point_list_t

Definition at line 32 of file cyl_geom.h.

Function Documentation

_findConvexHull() [1/2]

template<class inT>

void JetGeom::_findConvexHull	(	point_set_t &	inSet,
		inT &	outSet )

_findConvexHull() [2/2]

template<class T>

void JetGeom::_findConvexHull	(	point_set_t &	inSet,
		T &	outSet )

Definition at line 332 of file cyl_geom.h.

                                                    {
 
  if(inSet.size()<4){  
    outSet.insert(outSet.begin(), inSet.begin(), inSet.end() );
    return;
  }
  
  point_set_t::iterator s_it = inSet.begin();
  point_t point00 = (*s_it);
  point_t point01= point00;
  while(point01.first == point00.first){
    ++s_it;
    point01 = *s_it;
  }
  --s_it; point01 = *s_it; 
 
  s_it = inSet.end(); --s_it;
  point_t point11 = (*s_it);
  point_t point10= point11;
  while(point10.first == point11.first){
    --s_it;
    point10 = *s_it;
  }
  ++s_it; point10 = *s_it; 
 
  // lower line :
  line_t lmin(point00, point10);
  // lower line :
  line_t lmax(point01, point11);
    
  // fill upper and lower list :
  point_list_t lowPoints, upPoints;
 
  s_it = inSet.begin();
  if(point00 == point01 ){ // make sure point is in both list
    lowPoints.push_back(point00);
    upPoints.push_back(point00);
    ++s_it;
  }
  //std::cout << " lp size =" << lowPoints.size() << std::endl;
  point_set_t::iterator s_itE = inSet.end(); 
  --s_itE; // we'll deal ws_ith the end by hand
  for(; s_it!= s_itE; ++s_it){
    point_t p = *s_it;
    //std::cout << " point "<< p.first << " , "<< p.second << std::endl;
    if( lmin.is_below(p)) {
      lowPoints.push_back(p);
      continue;
    }
    if( lmax.is_above(p)) {
      upPoints.push_front(p); // insert front soit is well sorted
    }
 
  }
  //std::cout << " lp size =" << lowPoints.size() << std::endl;
  if(point11 == point10 ){ // make sure point is in both list
    lowPoints.push_back(point11);
    upPoints.push_front(point11);
    ++s_it;
  }else{
    lowPoints.push_back(point10);
    upPoints.push_front(point00);
  }
  //std::cout << " lp size =" << lowPoints.size() << std::endl;
  //std::cout << lowPoints.size() << " " << upPoints.size() << std::endl;
 
  // find lower hull :
  point_list_t lowHull;
  point_list_t::iterator it = lowPoints.begin();
  point_list_t::iterator itE = lowPoints.end();
  lowHull.push_back(point00); // here point00 == (*it)
  ++it;
  lowHull.push_back(*it);  // always put next point in stack
  ++it;
  unsigned int nn = lowPoints.size();
  if(nn>2){
    //std::cout << "building low hull : "<< lowPoints.size() <<std::endl; 
    while(it!=itE){    
      testHullLine(lowHull, *it);
      ++it;
    }
  }
  // find upper hull :
  point_list_t upHull;
  it = upPoints.begin();
  itE = upPoints.end();
  upHull.push_back(point11); // here point11 == (*it)
  ++it;
  upHull.push_back(*it);  // always put next point in stack
  ++it; 
  if(upPoints.size()>2){
    //std::cout << "building up hull : "<< upPoints.size() <<std::endl; 
    while(it!=itE){   
      testHullLine(upHull, *it);    
      ++it;
    }
  }
//   std::cout << " low size = "<< lowHull.size() << std::endl;
//   std::cout << " up size = "<< upHull.size() << std::endl;
  // join Hull !
  outSet.insert(outSet.begin(), lowHull.begin(), lowHull.end() );
  outSet.insert((outSet.end()), ++(upHull.begin()), --(upHull.end()) ); // avoid duplication
  
  //  std::cout << " Out size = "<< outSet.size() << std::endl;
 
}

abs_dphi()

float JetGeom::abs_dphi ( float phi1, float phi2 )

inline

Definition at line 206 of file cyl_geom.h.

                                             {
  float d = fabs(phi1 - phi2);
  return d < M_PI ?  d: fabs(d-2*M_PI);
}

clear_delete()

template<class T>

void JetGeom::clear_delete

(

T &

container

)

Definition at line 148 of file cyl_geom.h.

                               {
  typedef typename T::iterator it_t;
  it_t it =  container.begin();
  it_t itE = container.end();
  for(; it != itE; ++it) delete *it;
  container.clear();
}

delete_content()

template<class T>

void JetGeom::delete_content

(

T &

container

)

Definition at line 156 of file cyl_geom.h.

                                 {
  typedef typename T::iterator it_t;
  it_t it =  container.begin();
  it_t itE = container.end();
  for(; it != itE; ++it) delete *it;
}

deltaPhi() [1/2]

float JetGeom::deltaPhi ( float phi1, float phi2 )

inline

Definition at line 210 of file cyl_geom.h.

                                             {
  return in_mPI_pPI(phi1-phi2);
}

deltaPhi() [2/2]

float JetGeom::deltaPhi ( point_t & p1, point_t & p2 )

inline

Definition at line 213 of file cyl_geom.h.

                                               {
  return deltaPhi(p1.second,p2.second);
}

deltaR()

float JetGeom::deltaR ( point_t & p1, point_t & p2 )

inline

distances between points

Definition at line 240 of file cyl_geom.h.

                                             {
  return  sqrt( deltaR2(p1,p2) );
}

deltaR2()

float JetGeom::deltaR2 ( point_t & p1, point_t & p2 )

inline

Definition at line 236 of file cyl_geom.h.

                                              {
  return  (p1.first-p2.first)*(p1.first-p2.first) + 
        abs_dphi(p1.second,p2.second)*abs_dphi(p1.second,p2.second) ;
}

findConvexHull() [1/2]

template<class inT, class ouT>

void JetGeom::findConvexHull	(	inT &	inSet,
		ouT &	outSet )

Find convex hull of a set of points in euclidian plan.

The hull points are filled into

Parameters

outSet

Definition at line 317 of file cyl_geom.h.

                                             {
  point_set_t rset;
  typedef typename inT::iterator it_t;
  it_t it = inSet.begin();
  it_t itE = inSet.end();
  for(; it!=itE; ++it) rset.insert(*it);
  _findConvexHull(rset,outSet);
}

findConvexHull() [2/2]

template<class ouT>

void JetGeom::findConvexHull	(	point_set_t &	inSet,
		ouT &	outSet )

specialization for point_set_t

Definition at line 327 of file cyl_geom.h.

                                                     {
  _findConvexHull(inSet, outSet);
}

fix2pi()

void JetGeom::fix2pi ( point_t & p )

inline

convert

Parameters

p	second coordinate (phi) into a value in [-Pi,Pi]

Definition at line 221 of file cyl_geom.h.

                              {
  while(p.second < -M_PI) p.second += 2*M_PI;
  while(p.second >= M_PI) p.second -= 2*M_PI;
}

getMeanPhi()

template<class T>

float JetGeom::getMeanPhi

(

T &

set

)

return average phi (i.e.

second coordinate) of the point container

Parameters

set,if

max(deltaphi) < pi (i.e. points are located on one side of cylinder) otherwise return -10.

Definition at line 263 of file cyl_geom.h.

                        {
  // return mean
  typedef typename T::iterator it_t;
  it_t it = set.begin();
  it_t end = set.end();
  point_t fp = (*it);
  float max= 0,min=0, mean=0;
  int n=0;
  for(; it!= end; ++it){
    float phi = recenter((*it),fp).second;
    if( phi >0){
      max = phi>max ? phi : max;
    }else{
      min = phi<min ? phi : min;
    }
    mean+=phi; n++;
  }
  if ( (max-min) <= (M_PI) )
    return in_mPI_pPI(mean/n+fp.second);
  else return -10;
}

in_mPI_pPI()

float JetGeom::in_mPI_pPI ( float phi )

inline

convert

Parameters

phi	into a value in [-Pi,Pi]

Definition at line 216 of file cyl_geom.h.

                                   {
  while(phi < -M_PI) phi += 2*M_PI;
  while(phi >= M_PI) phi -= 2*M_PI;
  return phi;
}

listToSet()

void JetGeom::listToSet	(	point_list_t &	inList,
		point_set_t &	outSet )

Definition at line 27 of file cyl_geom.cxx.

                                                         {
  point_list_t::iterator it = inList.begin();
  point_list_t::iterator itE = inList.end();
  point_set_t::iterator s_it = outSet.begin();
  for(; it!=itE; ++it){
    s_it = outSet.insert(s_it, *it);
  }  
}

max_deltaR()

template<class T>

float JetGeom::max_deltaR	(	point_t	p,
		T &	set )

Return max distance betweens point.

Parameters

p	and points of
set

Definition at line 164 of file cyl_geom.h.

                                   {
  typedef typename T::iterator it_t;
  it_t it  = set.begin();
  it_t itE = set.end();
  float r=0;
  for(; it != itE; ++it){
    float t = deltaR(p, *it);
    if(t>r) r=t;
  }
  return r;
}

polygon_area()

template<class T>

float JetGeom::polygon_area

(

T &

line

)

Definition at line 177 of file cyl_geom.h.

                           {
  typedef typename T::iterator it_t;
  it_t it = line.begin();
  it_t itE = line.end();
  float a=0;
  for(; it != itE; ++it){
    it_t itp=it;
    ++itp;
    if(itp == itE) itp =  line.begin();
    a += ( (*it).first*(*itp).second - (*itp).first*(*it).second );
  }
  return a/2;
}

polygon_lenght()

template<class T>

float JetGeom::polygon_lenght

(

T &

line

)

Definition at line 192 of file cyl_geom.h.

                             {
  typedef typename T::iterator it_t;
  it_t it = line.begin();
  it_t itE = line.end();
  float a=0;
  for(; it != itE; ++it){
    it_t itp=it;
    ++itp;
    if(itp == itE) itp =  line.begin();
    a += deltaR(*it,*itp);
  }
  return a;
}

recenter() [1/2]

point_t JetGeom::recenter ( const point_t & p, const point_t & center )

inline

Definition at line 226 of file cyl_geom.h.

                                                                {
  point_t n(p.first, p.second - center.second);
  fix2pi(n);
  return n;
}

recenter() [2/2]

point_t JetGeom::recenter ( const point_t & p, float phicenter )

inline

Definition at line 231 of file cyl_geom.h.

                                                          {
  point_t n(p.first, p.second - phicenter);
  fix2pi(n);
  return n;
}

recenter_set() [1/2]

template<class T, class T2>

void JetGeom::recenter_set	(	T &	inSet,
		T2 &	outSet )

copy

Parameters

inSet	into
outSet	with all phi coordonitates recentered by average phi of
inSet

Definition at line 256 of file cyl_geom.h.

                                       {
  float phicenter = getMeanPhi(inSet);
  if (phicenter <-9) return;
  recenter_set(inSet,outSet,phicenter);
}

recenter_set() [2/2]

template<class T, class T2>

void JetGeom::recenter_set	(	T &	inSet,
		T2 &	outSet,
		float	phicenter )

copy

Parameters

inSet	into
outSet	with all phi coordonitates recnetered by phicenter

Definition at line 245 of file cyl_geom.h.

                                                        {
  typedef typename T::iterator it_t;
  typedef typename T2::iterator it_t2;
  it_t it = inSet.begin();
  it_t itE = inSet.end();
  it_t2 it2 = outSet.begin();
  for(; it!= itE; ++it){
    it2 = outSet.insert(it2,recenter(*it,phicenter));
  }
}

testHullLine()

void JetGeom::testHullLine	(	point_list_t &	hull,
		point_t	p )

Definition at line 9 of file cyl_geom.cxx.

                                                {
  // helper function for findConvexHull
  point_list_t::iterator it_prev = hull.end();--it_prev;
  point_list_t::iterator it_pprev = it_prev; --it_pprev;
  line_t l(*it_pprev, *it_prev);
  //   std::cout << " hull : "<< hull.size()<< "  p.phi ="<<p.second  <<std::endl;
  //   std::cout << "      "<< (*it_prev).first<< " " << (*it_prev).second << std::endl;
  //   std::cout << "      "<< (*it_pprev).first << "  "<<(*it_pprev).second << std::endl;
  //   std::cout << "      -> "<< p.first << "  "<< p.second << std::endl;
  if ( ! l.is_left(p) && (hull.size()>2)){
    //std::cout << "  is right !"  << std::endl;
    hull.pop_back(); // remove last
    testHullLine(hull, p);
  }else{
    //std::cout << "  is left !"  << std::endl;
    hull.push_back(p);
  }
}