From f527cde6342c5b8109a20f0a6b483327c6569844 Mon Sep 17 00:00:00 2001
From: salinasd <salinasd@636b058d-ea47-450e-bf9e-a15bfbe3eedb>
Date: Tue, 27 Jan 2015 10:20:13 +0000
Subject: Merge GudhUI, a UI for gudhi based on Qt

git-svn-id: svn+ssh://scm.gforge.inria.fr/svnroot/gudhi/trunk@427 636b058d-ea47-450e-bf9e-a15bfbe3eedb

Former-commit-id: 17fedd974f14a8225b27d94361e835964eeb5cba
---
 src/GudhUI/utils/Furthest_point_epsilon_net.h | 134 ++++++++++++++++++++++++++
 1 file changed, 134 insertions(+)
 create mode 100644 src/GudhUI/utils/Furthest_point_epsilon_net.h

(limited to 'src/GudhUI/utils/Furthest_point_epsilon_net.h')

diff --git a/src/GudhUI/utils/Furthest_point_epsilon_net.h b/src/GudhUI/utils/Furthest_point_epsilon_net.h
new file mode 100644
index 00000000..590b65c4
--- /dev/null
+++ b/src/GudhUI/utils/Furthest_point_epsilon_net.h
@@ -0,0 +1,134 @@
+/*
+ * Furthest_point_epsilon_net.h
+ *
+ *  Created on: Sep 26, 2014
+ *      Author: dsalinas
+ */
+
+#ifndef FURTHEST_POINT_EPSILON_NET_H_
+#define FURTHEST_POINT_EPSILON_NET_H_
+
+#include "utils/UI_utils.h"
+#include <vector>
+
+/**
+ * Computes an epsilon net with furthest point strategy.
+ */
+template<typename SkBlComplex> class Furthest_point_epsilon_net{
+private:
+	SkBlComplex& complex_;
+	typedef typename SkBlComplex::Vertex_handle Vertex_handle;
+	typedef typename SkBlComplex::Edge_handle Edge_handle;
+
+	/**
+	 * Let V be the set of vertices.
+	 * Initially v0 is one arbitrarly vertex and the set V0 is {v0}.
+	 * Then Vk is computed as follows.
+	 * First we compute the vertex pk that is the furthest from Vk
+	 * then Vk = Vk \cup pk.
+	 * The radius of pk is its distance to Vk and its meeting vertex
+	 * is the vertex of Vk for which this distance is achieved.
+	 */
+	struct Net_filtration_vertex{
+		Vertex_handle vertex_handle;
+		Vertex_handle meeting_vertex;
+		double radius;
+
+
+		Net_filtration_vertex(
+				Vertex_handle vertex_handle_,
+				Vertex_handle meeting_vertex_,
+				double radius_):
+					vertex_handle(vertex_handle_),meeting_vertex(meeting_vertex_),radius(radius_)
+		{}
+
+		bool operator<(const Net_filtration_vertex& other ) const{
+			return radius < other.radius;
+		}
+
+	};
+
+public:
+
+
+	std::vector<Net_filtration_vertex> net_filtration_;
+
+	/**
+	 * @brief Modify complex to be the expansion of the k-nearest neighbor
+	 * symetric graph.
+	 */
+	Furthest_point_epsilon_net(SkBlComplex& complex):
+		complex_(complex)
+	{
+		if(!complex.empty()){
+			init_filtration();
+			for(int k = 2; k < net_filtration_.size(); ++k){
+				update_radius_value(k);
+			}
+		}
+	}
+
+	//xxx does not work if complex not full
+	double radius(Vertex_handle v){
+		return net_filtration_[v.vertex].radius;
+	}
+
+
+
+
+private:
+
+	void init_filtration(){
+		Vertex_handle v0 = *(complex_.vertex_range().begin());
+		net_filtration_.reserve(complex_.num_vertices());
+		for(auto v : complex_.vertex_range()){
+			if(v != v0)
+				net_filtration_.push_back(
+						Net_filtration_vertex(v,
+								Vertex_handle(-1),
+								squared_eucl_distance(v,v0))
+				);
+		}
+		net_filtration_.push_back(Net_filtration_vertex(v0,Vertex_handle(-1),1e10));
+		auto n = net_filtration_.size();
+		sort_filtration(n-1);
+	}
+
+	void update_radius_value(int k){
+		int n = net_filtration_.size();
+		int index_to_update = n-k;
+		for(int i = 0; i< index_to_update; ++i){
+			net_filtration_[i].radius = (std::min)(net_filtration_[i].radius ,
+					squared_eucl_distance(
+							net_filtration_[i].vertex_handle,
+							net_filtration_[index_to_update].vertex_handle
+					)
+			);
+		}
+		sort_filtration(n-k);
+	}
+
+	/**
+	 * sort all i first elements.
+	 */
+	void sort_filtration(int i){
+		std::sort(net_filtration_.begin(),net_filtration_.begin()+ i);
+	}
+
+	double squared_eucl_distance(Vertex_handle v1,Vertex_handle v2) const{
+		return std::sqrt(Geometry_trait::Squared_distance_d()(
+				complex_.point(v1),complex_.point(v2))
+		);
+	}
+
+	void print_filtration() const{
+		for(auto v : net_filtration_){
+			std::cerr <<"v="<<v.vertex_handle<<"-> d="<<v.radius<<std::endl;
+		}
+	}
+
+};
+
+
+
+#endif /* FURTHEST_POINT_EPSILON_NET_H_ */
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