Merge last trunk modifications

git-svn-id: svn+ssh://scm.gforge.inria.fr/svnroot/gudhi/branches/distance_matrix_in_rips_module@1938 636b058d-ea47-450e-bf9e-a15bfbe3eedb

Former-commit-id: 8af39a00b9134dbcc77883412c29d7184479979b

2 files changed, 64 insertions, 0 deletions

diff --git a/src/Subsampling/example/CMakeLists.txt b/src/Subsampling/example/CMakeLists.txt
index 54349f0c..0fd3335c 100644
--- a/src/Subsampling/example/CMakeLists.txt
+++ b/src/Subsampling/example/CMakeLists.txt
@@ -6,6 +6,7 @@ if(CGAL_FOUND)
     if (EIGEN3_FOUND)
       add_executable(Subsampling_example_pick_n_random_points example_pick_n_random_points.cpp)
       add_executable(Subsampling_example_choose_n_farthest_points example_choose_n_farthest_points.cpp)
+      add_executable(Subsampling_example_custom_kernel example_custom_kernel.cpp)
       add_executable(Subsampling_example_sparsify_point_set example_sparsify_point_set.cpp)
       target_link_libraries(Subsampling_example_sparsify_point_set ${CGAL_LIBRARY})
 
diff --git a/src/Subsampling/example/example_custom_kernel.cpp b/src/Subsampling/example/example_custom_kernel.cpp
new file mode 100644
index 00000000..25b5bf6c
--- /dev/null
+++ b/src/Subsampling/example/example_custom_kernel.cpp
@@ -0,0 +1,63 @@
+#include <gudhi/choose_n_farthest_points.h>
+
+#include <CGAL/Epick_d.h>
+#include <CGAL/Random.h>
+
+#include <vector>
+#include <iterator>
+
+
+/* The class Kernel contains a distance function defined on the set of points {0, 1, 2, 3}
+ * and computes a distance according to the matrix:
+ * 0 1 2 4
+ * 1 0 4 2
+ * 2 4 0 1
+ * 4 2 1 0
+ */
+class Kernel {
+ public:
+  typedef double FT;
+  typedef unsigned Point_d;
+
+  // Class Squared_distance_d
+  class Squared_distance_d {
+   private:
+    std::vector<std::vector<FT>> matrix_;
+
+   public:
+    Squared_distance_d() {
+      matrix_.push_back(std::vector<FT>({0, 1, 2, 4}));
+      matrix_.push_back(std::vector<FT>({1, 0, 4, 2}));
+      matrix_.push_back(std::vector<FT>({2, 4, 0, 1}));
+      matrix_.push_back(std::vector<FT>({4, 2, 1, 0}));
+    }
+
+    FT operator()(Point_d p1, Point_d p2) {
+      return matrix_[p1][p2];
+    }
+  };
+
+  // Constructor
+  Kernel() {}
+
+  // Object of type Squared_distance_d
+  Squared_distance_d squared_distance_d_object() const {
+    return Squared_distance_d();
+  }
+};
+
+int main(void) {
+  typedef Kernel K;
+  typedef typename K::Point_d Point_d;
+
+  K k;
+  std::vector<Point_d> points = {0, 1, 2, 3};
+  std::vector<Point_d> results;
+
+  Gudhi::subsampling::choose_n_farthest_points(k, points, 2, std::back_inserter(results));
+  std::cout << "Before sparsification: " << points.size() << " points.\n";
+  std::cout << "After  sparsification: " << results.size() << " points.\n";
+  std::cout << "Result table: {" << results[0] << "," << results[1] << "}\n";
+
+  return 0;
+}