added betti sequences

git-svn-id: svn+ssh://scm.gforge.inria.fr/svnroot/gudhi/branches/kernels@3431 636b058d-ea47-450e-bf9e-a15bfbe3eedb

Former-commit-id: 4680471ce781468c247c40fb5e6eb699dce890c8

2 files changed, 108 insertions, 12 deletions

diff --git a/src/Persistence_representations/include/gudhi/Betti_sequence.h b/src/Persistence_representations/include/gudhi/Betti_sequence.h
new file mode 100644
index 00000000..57c52ad2
--- /dev/null
+++ b/src/Persistence_representations/include/gudhi/Betti_sequence.h
@@ -0,0 +1,95 @@
+/*    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(s):       Mathieu Carriere
+ *
+ *    Copyright (C) 2018  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 BETTI_SEQUENCE_H_
+#define BETTI_SEQUENCE_H_
+
+// gudhi include
+#include <gudhi/read_persistence_from_file.h>
+#include <gudhi/common_persistence_representations.h>
+#include <gudhi/Debug_utils.h>
+
+// standard include
+#include <cmath>
+#include <iostream>
+#include <vector>
+#include <limits>
+#include <fstream>
+#include <sstream>
+#include <algorithm>
+#include <string>
+#include <utility>
+#include <functional>
+
+namespace Gudhi {
+namespace Persistence_representations {
+
+/**
+ * \class Betti_sequence gudhi/Betti_sequence.h
+ * \brief A class implementing Betti sequences
+ *
+ * \ingroup Persistence_representations
+ *
+ * \details
+**/
+
+class Betti_sequence {
+
+  protected:
+   Persistence_diagram diagram;
+   int res_x, nb_cv;
+   double min_x, max_x;
+
+  public:
+
+   /** \brief Betti_sequence constructor.
+    * \ingroup Betti_sequence
+    *
+    * @param[in] _diagram    persistence diagram.
+    * @param[in] _min_x      minimum value of samples.
+    * @param[in] _max_x      maximum value of samples.
+    * @param[in] _res_x      number of samples.
+    *
+    */
+   Betti_sequence(const Persistence_diagram & _diagram, double _min_x = 0.0, double _max_x = 1.0, int _res_x = 10){diagram = _diagram; min_x = _min_x; max_x = _max_x; res_x = _res_x;}
+
+   /** \brief Computes the Betti sequences of a diagram.
+    * \ingroup Betti_sequence
+    *
+    */
+   std::vector<int> vectorize() const {
+     int num_pts = diagram.size(); double step = (max_x - min_x)/(res_x - 1);
+     std::vector<int> bs(res_x); for(int i = 0; i < res_x; i++)  bs[i] = 0;
+     for(int j = 0; j < num_pts; j++){
+       double px = diagram[j].first; double py = diagram[j].second;
+       int first = std::ceil((px-min_x)/step); int last = std::ceil((py-min_x)/step);
+       for(int i = first; i < last; i++)  bs[i] += 1;
+     }
+
+     return bs;
+   }
+
+}; // class Betti_sequence
+}  // namespace Persistence_representations
+}  // namespace Gudhi
+
+#endif  // BETTI_SEQUENCE_H_
diff --git a/src/Persistence_representations/include/gudhi/Persistence_landscape_on_grid_exact.h b/src/Persistence_representations/include/gudhi/Persistence_landscape_on_grid_exact.h
index 25f71e27..52f24195 100644
--- a/src/Persistence_representations/include/gudhi/Persistence_landscape_on_grid_exact.h
+++ b/src/Persistence_representations/include/gudhi/Persistence_landscape_on_grid_exact.h
@@ -82,24 +82,25 @@ class Persistence_landscape_on_grid_exact {
     */
    std::vector<std::vector<double> > vectorize() const {
      std::vector<std::vector<double> >  ls; for(int i = 0; i < nb_ls; i++)  ls.emplace_back();
-     int num_pts = diagram.size(); double step = (max_x - min_x)/res_x;
+     int num_pts = diagram.size(); double step = (max_x - min_x)/(res_x - 1);
+
+     std::vector<std::vector<double> > ls_t; for(int i = 0; i < res_x; i++)  ls_t.emplace_back();
+     for(int j = 0; j < num_pts; j++){
+       double px = diagram[j].first; double py = diagram[j].second; double mid = (px+py)/2;
+       int first = std::ceil((px-min_x)/step); int middle = std::ceil((mid-min_x)/step); int last = std::ceil((py-min_x)/step); double x = min_x + first*step;
+       for(int i = first; i < middle; i++){  double value = std::sqrt(2)*(x-px); ls_t[i].push_back(value); x += step;  }
+       for(int i = middle; i < last; i++){   double value = std::sqrt(2)*(py-x); ls_t[i].push_back(value); x += step;  }
+     }
 
      for(int i = 0; i < res_x; i++){
-       double x = min_x + i*step; double t = x / std::sqrt(2); std::vector<double> events;
-       for(int j = 0; j < num_pts; j++){
-         double px = diagram[j].first; double py = diagram[j].second;
-         if(t >= px && t <= py){  if(t >= (px+py)/2)  events.push_back(std::sqrt(2)*(py-t)); else  events.push_back(std::sqrt(2)*(t-px));  }
-       }
-
-       std::sort(events.begin(), events.end(), [](const double & a, const double & b){return a > b;}); int nb_events = events.size();
-       for (int j = 0; j < nb_ls; j++){  if(j < nb_events)  ls[j].push_back(events[j]);  else  ls[j].push_back(0);  }
+       std::sort(ls_t[i].begin(), ls_t[i].end(), [](const double & a, const double & b){return a > b;});
+       int nb_events_i = ls_t[i].size();
+       for (int j = 0; j < nb_ls; j++){  if(j < nb_events_i)  ls[j].push_back(ls_t[i][j]);  else  ls[j].push_back(0);  }
      }
+
      return ls;
    }
 
-
-
-
 }; // class Persistence_landscape_on_grid_exact
 }  // namespace Persistence_representations
 }  // namespace Gudhi