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/*
* Lloyd.h
*
* Created on: Sep 25, 2014
* Author: dsalinas
*/
#ifndef LLOYD_H_
#define LLOYD_H_
#include <vector>
/**
* Iteratively puts every vertex at the center of its neighbors
*/
template<typename SkBlComplex> class Lloyd_builder{
private:
SkBlComplex& complex_;
int dim;
public:
typedef typename SkBlComplex::Vertex_handle Vertex_handle;
/**
* @brief Modify complex to be the expansion of the k-nearest neighbor
* symetric graph.
*/
Lloyd_builder(SkBlComplex& complex,unsigned num_iterations):complex_(complex),dim(-1){
if(!complex_.empty()){
dim = get_dimension();
while(num_iterations--){
std::list<Point> new_points;
for(auto v : complex.vertex_range())
new_points.push_back(barycenter_neighbors(v));
auto new_points_it = new_points.begin();
for(auto v : complex.vertex_range())
complex_.point(v) = *(new_points_it++);
}
}
}
private:
int get_dimension(){
assert(!complex_.empty());
for(auto v : complex_.vertex_range())
return complex_.point(v).dimension();
return -1;
}
Point barycenter_neighbors(Vertex_handle v) const{
if(complex_.degree(v)==0)
return complex_.point(v);
std::vector<double> res(dim,0);
unsigned num_points = 0;
for(auto nv : complex_.vertex_range(v)){
++num_points;
const Point& point = complex_.point(nv);
assert(point.dimension() == dim);
for(int i = 0; i < point.dimension() ; ++i)
res[i] += point[i];
}
for(auto& x : res)
x/= num_points;
return Point(dim,res.begin(),res.end());
}
double squared_eucl_distance(const Point& p1,const Point& p2) const{
return Geometry_trait::Squared_distance_d()(p1,p2);
}
};
#endif /* LLOYD_H_ */
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