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git-svn-id: svn+ssh://scm.gforge.inria.fr/svnroot/gudhi/branches/bottleneck_integration@1794 636b058d-ea47-450e-bf9e-a15bfbe3eedb

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diff --git a/src/Bottleneck_distance/include/gudhi/Persistence_graph.h b/src/Bottleneck_distance/include/gudhi/Persistence_graph.h
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+/*    This file is part of the Gudhi Library. The Gudhi library
+ *    (Geometric Understanding in Higher Dimensions) is a generic C++
+ *    library for computational topology.
+ *
+ *    Author:       Francois Godi
+ *
+ *    Copyright (C) 2015  INRIA (France)
+ *
+ *    This program is free software: you can redistribute it and/or modify
+ *    it under the terms of the GNU General Public License as published by
+ *    the Free Software Foundation, either version 3 of the License, or
+ *    (at your option) any later version.
+ *
+ *    This program is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    GNU General Public License for more details.
+ *
+ *    You should have received a copy of the GNU General Public License
+ *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#ifndef PERSISTENCE_GRAPH_H_
+#define PERSISTENCE_GRAPH_H_
+
+#include <vector>
+#include <set>
+#include <gudhi/Internal_point.h>
+
+namespace Gudhi {
+
+namespace bottleneck_distance {
+
+
+/** \internal \brief Structure representing an euclidean bipartite graph containing
+ *  the points from the two persistence diagrams (including the projections).
+ *
+ * \ingroup bottleneck_distance
+ */
+class Persistence_graph {
+public:
+    /** \internal \brief Initializer taking 2 Point (concept) ranges as parameters. */
+    template<typename Persistence_diagram1, typename Persistence_diagram2>
+    Persistence_graph(const Persistence_diagram1& diag1, const Persistence_diagram2& diag2, double e);
+    /** \internal \brief Is the given point from U the projection of a point in V ? */
+    bool on_the_u_diagonal(int u_point_index) const;
+    /** \internal \brief Is the given point from V the projection of a point in U ? */
+    bool on_the_v_diagonal(int v_point_index) const;
+    /** \internal \brief Given a point from V, returns the corresponding (projection or projector) point in U. */
+    int corresponding_point_in_u(int v_point_index) const;
+    /** \internal \brief Given a point from U, returns the corresponding (projection or projector) point in V. */
+    int corresponding_point_in_v(int u_point_index) const;
+    /** \internal \brief Given a point from U and a point from V, returns the distance between those points. */
+    double distance(int u_point_index, int v_point_index) const;
+    /** \internal \brief Returns size = |U| = |V|. */
+    int size() const;
+    /** \internal \brief Returns the O(n^2) sorted distances between the points. */
+    std::vector<double> sorted_distances() const;
+    /** \internal \brief Returns an upper bound of the diameter of the convex hull */
+    double diameter_bound() const;
+    /** \internal \brief Returns the corresponding internal point */
+    Internal_point get_u_point(int u_point_index) const;
+    /** \internal \brief Returns the corresponding internal point */
+    Internal_point get_v_point(int v_point_index) const;
+
+private:
+    std::vector<Internal_point> u;
+    std::vector<Internal_point> v;
+};
+
+template<typename Persistence_diagram1, typename Persistence_diagram2>
+Persistence_graph::Persistence_graph(const Persistence_diagram1 &diag1,
+                                     const Persistence_diagram2 &diag2, double e)
+    : u(), v()
+{
+    for (auto it = diag1.cbegin(); it != diag1.cend(); ++it)
+        if (it->second - it->first > e)
+            u.push_back(Internal_point(std::get<0>(*it), std::get<1>(*it), u.size()));
+    for (auto it = diag2.cbegin(); it != diag2.cend(); ++it)
+        if (it->second - it->first > e)
+            v.push_back(Internal_point(std::get<0>(*it), std::get<1>(*it), v.size()));
+    if (u.size() < v.size())
+        swap(u, v);
+}
+
+inline bool Persistence_graph::on_the_u_diagonal(int u_point_index) const {
+    return u_point_index >= static_cast<int> (u.size());
+}
+
+inline bool Persistence_graph::on_the_v_diagonal(int v_point_index) const {
+    return v_point_index >= static_cast<int> (v.size());
+}
+
+inline int Persistence_graph::corresponding_point_in_u(int v_point_index) const {
+    return on_the_v_diagonal(v_point_index) ?
+                v_point_index - static_cast<int> (v.size()) : v_point_index + static_cast<int> (u.size());
+}
+
+inline int Persistence_graph::corresponding_point_in_v(int u_point_index) const {
+    return on_the_u_diagonal(u_point_index) ?
+                u_point_index - static_cast<int> (u.size()) : u_point_index + static_cast<int> (v.size());
+}
+
+inline double Persistence_graph::distance(int u_point_index, int v_point_index) const {
+    if (on_the_u_diagonal(u_point_index) && on_the_v_diagonal(v_point_index))
+        return 0.;
+    Internal_point p_u = get_u_point(u_point_index);
+    Internal_point p_v = get_v_point(v_point_index);
+    return std::max(std::fabs(p_u.x() - p_v.x()), std::fabs(p_u.y() - p_v.y()));
+}
+
+inline int Persistence_graph::size() const {
+    return static_cast<int> (u.size() + v.size());
+}
+
+inline std::vector<double> Persistence_graph::sorted_distances() const {
+    // could be optimized
+    std::set<double> sorted_distances;
+    sorted_distances.emplace(0.);
+    for (int u_point_index = 0; u_point_index < size(); ++u_point_index)
+        for (int v_point_index = 0; v_point_index < size(); ++v_point_index)
+            sorted_distances.emplace(distance(u_point_index, v_point_index));
+    return std::vector<double>(sorted_distances.begin(),sorted_distances.end());
+}
+
+inline Internal_point Persistence_graph::get_u_point(int u_point_index) const {
+    if (!on_the_u_diagonal(u_point_index))
+        return u.at(u_point_index);
+    Internal_point projector = v.at(corresponding_point_in_v(u_point_index));
+    double m = (projector.x() + projector.y()) / 2;
+    return Internal_point(m,m,u_point_index);
+}
+
+inline Internal_point Persistence_graph::get_v_point(int v_point_index) const {
+    if (!on_the_v_diagonal(v_point_index))
+        return v.at(v_point_index);
+    Internal_point projector = u.at(corresponding_point_in_u(v_point_index));
+    double m = (projector.x() + projector.y()) / 2;
+    return Internal_point(m,m,v_point_index);
+}
+
+inline double Persistence_graph::diameter_bound() const {
+    double max = 0.;
+    for(auto it = u.cbegin(); it != u.cend(); it++)
+        max = std::max(max,it->y());
+    for(auto it = v.cbegin(); it != v.cend(); it++)
+        max = std::max(max,it->y());
+    return max;
+}
+
+}  // namespace bottleneck_distance
+
+}  // namespace Gudhi
+
+#endif  // PERSISTENCE_GRAPH_H_