Add an example

git-svn-id: svn+ssh://scm.gforge.inria.fr/svnroot/gudhi/branches/subsampling_and_spatialsearching@1334 636b058d-ea47-450e-bf9e-a15bfbe3eedb

Former-commit-id: df8ee96b7cbfcc4380e49956b2495ec8bf12895e

2 files changed, 80 insertions, 0 deletions

diff --git a/src/Subsampling/example/CMakeLists.txt b/src/Subsampling/example/CMakeLists.txt
new file mode 100644
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+++ b/src/Subsampling/example/CMakeLists.txt
@@ -0,0 +1,29 @@
+cmake_minimum_required(VERSION 2.6)
+project(Subsampling_examples)
+
+if(CGAL_FOUND)
+  if (NOT CGAL_VERSION VERSION_LESS 4.8.0)
+    message(STATUS "CGAL version: ${CGAL_VERSION}.")
+
+    find_package(Eigen3 3.1.0)
+    if (EIGEN3_FOUND)
+      message(STATUS "Eigen3 version: ${EIGEN3_VERSION}.")
+      include( ${EIGEN3_USE_FILE} )
+      include_directories (BEFORE "../../include")
+
+      #add_executable( Subsampling_example_pick_random_points example_pick_random_points.cpp )
+
+      #add_executable( Subsampling_example_choose_farthest_point example_choose_farthest_point.cpp )
+      #target_link_libraries(Subsampling_example_choose_farthest_point ${Boost_SYSTEM_LIBRARY} ${Boost_UNIT_TEST_FRAMEWORK_LIBRARY})
+      
+      add_executable(Subsampling_example_sparsify_point_set example_sparsify_point_set.cpp)
+      target_link_libraries(Subsampling_example_sparsify_point_set ${Boost_UNIT_TEST_FRAMEWORK_LIBRARY})
+    else()
+      message(WARNING "Eigen3 not found. Version 3.1.0 is required for Subsampling feature.")
+    endif()
+  else()
+    message(WARNING "CGAL version: ${CGAL_VERSION} is too old to compile Subsampling examples. Version 4.8.0 is required.")
+  endif ()
+else()
+  message(WARNING "CGAL not found. It is required for the Subsampling examples.")
+endif()
diff --git a/src/Subsampling/example/example_sparsify_point_set.cpp b/src/Subsampling/example/example_sparsify_point_set.cpp
new file mode 100644
index 00000000..57171082
--- /dev/null
+++ b/src/Subsampling/example/example_sparsify_point_set.cpp
@@ -0,0 +1,51 @@
+/*    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):       Clement Jamin
+ *
+ *    Copyright (C) 2016 INRIA
+ *
+ *    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/>.
+ */
+
+#include <gudhi/sparsify_point_set.h>
+
+#include <CGAL/Epick_d.h>
+#include <CGAL/Random.h>
+
+#include <array>
+#include <vector>
+#include <iterator>
+
+int main (void)
+{
+  typedef CGAL::Epick_d<CGAL::Dimension_tag<4> >   K;
+  typedef typename K::FT                           FT;
+  typedef typename K::Point_d                      Point_d;
+  
+  CGAL::Random rd;
+
+  std::vector<Point_d> points;
+  for (int i = 0 ; i < 500 ; ++i)
+    points.push_back(Point_d(std::array<FT,4>({rd.get_double(-1.,1),rd.get_double(-1.,1),rd.get_double(-1.,1),rd.get_double(-1.,1)})));
+
+  K k;
+  std::vector<Point_d> results;
+  Gudhi::subsampling::sparsify_point_set(k, points, 0.4, std::back_inserter(results));
+  std::cout << "Before sparsification: " << points.size() << " points.\n";
+  std::cout << "After  sparsification: " << results.size() << " points.\n";
+
+  return 0;
+}