Add example.

git-svn-id: svn+ssh://scm.gforge.inria.fr/svnroot/gudhi/branches/sparserips-glisse@3195 636b058d-ea47-450e-bf9e-a15bfbe3eedb

Former-commit-id: b8ded704563c6794c098f9b80b1a5e0200e84694

3 files changed, 58 insertions, 0 deletions

diff --git a/src/Rips_complex/doc/Intro_rips_complex.h b/src/Rips_complex/doc/Intro_rips_complex.h
index a9cfc0ab..96d90d98 100644
--- a/src/Rips_complex/doc/Intro_rips_complex.h
+++ b/src/Rips_complex/doc/Intro_rips_complex.h
@@ -182,6 +182,22 @@ namespace rips_complex {
  * 
  * \include Rips_complex/full_skeleton_rips_for_doc.txt
  * 
+ * \subsection sparseripspointscloudexample Example of a sparse Rips from a point cloud
+ * 
+ * This example builds the full sparse Rips of a set of 2D Euclidean points, then prints some minimal information about the complex.
+ * 
+ * \include Rips_complex/example_sparse_rips.cpp
+ * 
+ * When launching:
+ * 
+ * \code $> ./Rips_complex_example_sparse
+ * \endcode
+ *
+ * the program output may be (the exact output varies from one run to the next):
+ *
+ * \code Sparse Rips complex is of dimension 2 - 19 simplices - 7 vertices.
+ * \endcode
+ * 
  * \copyright GNU General Public License v3.                         
  * \verbatim  Contact: gudhi-users@lists.gforge.inria.fr \endverbatim
  */
diff --git a/src/Rips_complex/example/CMakeLists.txt b/src/Rips_complex/example/CMakeLists.txt
index 2940f164..8a22a6d8 100644
--- a/src/Rips_complex/example/CMakeLists.txt
+++ b/src/Rips_complex/example/CMakeLists.txt
@@ -11,11 +11,15 @@ add_executable ( Rips_complex_example_one_skeleton_from_distance_matrix example_
 
 add_executable ( Rips_complex_example_from_csv_distance_matrix example_rips_complex_from_csv_distance_matrix_file.cpp )
 
+# Point cloud
+add_executable ( Rips_complex_example_sparse example_sparse_rips_complex.cpp )
+
 if (TBB_FOUND)
   target_link_libraries(Rips_complex_example_from_off ${TBB_LIBRARIES})
   target_link_libraries(Rips_complex_example_one_skeleton_from_points ${TBB_LIBRARIES})
   target_link_libraries(Rips_complex_example_one_skeleton_from_distance_matrix ${TBB_LIBRARIES})
   target_link_libraries(Rips_complex_example_from_csv_distance_matrix ${TBB_LIBRARIES})
+  target_link_libraries(Rips_complex_example_sparse ${TBB_LIBRARIES})
 endif()
 
 add_test(NAME Rips_complex_example_one_skeleton_from_points
diff --git a/src/Rips_complex/example/example_sparse_rips.cpp b/src/Rips_complex/example/example_sparse_rips.cpp
new file mode 100644
index 00000000..49725f0a
--- /dev/null
+++ b/src/Rips_complex/example/example_sparse_rips.cpp
@@ -0,0 +1,38 @@
+#include <gudhi/Sparse_rips_complex.h>
+#include <gudhi/Simplex_tree.h>
+#include <gudhi/distance_functions.h>
+
+#include <iostream>
+#include <vector>
+
+int main() {
+  using Point = std::vector<double>;
+  using Simplex_tree = Gudhi::Simplex_tree<Gudhi::Simplex_tree_options_fast_persistence>;
+  using Filtration_value = Simplex_tree::Filtration_value;
+  using Complex = Gudhi::rips_complex::Sparse_rips_complex<Filtration_value>;
+
+  Point points[] = {
+    {1.0, 1.0},
+    {7.0, 0.0},
+    {4.0, 6.0},
+    {9.0, 6.0},
+    {0.0, 14.0},
+    {2.0, 19.0},
+    {9.0, 17.0}};
+
+  // ----------------------------------------------------------------------------
+  // Init from Euclidean points
+  // ----------------------------------------------------------------------------
+  double epsilon = 2; // very rough, no guarantees
+  Complex cpx(points, Gudhi::Euclidean_distance(), epsilon);
+
+  Simplex_tree stree;
+  cpx.create_complex(stree, 10);
+
+  // ----------------------------------------------------------------------------
+  // Display information about the complex
+  // ----------------------------------------------------------------------------
+  std::cout << "Sparse Rips complex is of dimension " << stree.dimension() <<
+               " - " << stree.num_simplices() << " simplices - " <<
+               stree.num_vertices() << " vertices." << std::endl;
+}