1 files changed, 86 insertions, 0 deletions
diff --git a/src/Contraction/example/Rips_contraction.cpp b/src/Contraction/example/Rips_contraction.cpp
new file mode 100644
index 00000000..b5ce06c1
--- /dev/null
+++ b/src/Contraction/example/Rips_contraction.cpp
@@ -0,0 +1,86 @@
+/*    This file is part of the Gudhi Library - https://gudhi.inria.fr/ - which is released under MIT.
+ *    See file LICENSE or go to https://gudhi.inria.fr/licensing/ for full license details.
+ *    Author(s):       David Salinas
+ *
+ *    Copyright (C) 2014 Inria
+ *
+ *    Modification(s):
+ *      - YYYY/MM Author: Description of the modification
+ */
+#include <gudhi/Edge_contraction.h>
+#include <gudhi/Skeleton_blocker.h>
+#include <gudhi/Off_reader.h>
+#include <gudhi/Point.h>
+#include <gudhi/Clock.h>
+
+#include <iostream>
+
+struct Geometry_trait {
+  typedef Point_d Point;
+};
+
+using Complex_geometric_traits = Gudhi::skeleton_blocker::Skeleton_blocker_simple_geometric_traits<Geometry_trait>;
+using Complex = Gudhi::skeleton_blocker::Skeleton_blocker_geometric_complex< Complex_geometric_traits >;
+using Profile = Gudhi::contraction::Edge_profile<Complex>;
+using Complex_contractor = Gudhi::contraction::Skeleton_blocker_contractor<Complex>;
+
+
+template<typename ComplexType>
+void build_rips(ComplexType& complex, double offset) {
+  if (offset <= 0) return;
+  auto vertices = complex.vertex_range();
+  for (auto p = vertices.begin(); p != vertices.end(); ++p)
+    for (auto q = p; ++q != vertices.end(); /**/) {
+      if (squared_dist(complex.point(*p), complex.point(*q)) < 4 * offset * offset)
+        complex.add_edge_without_blockers(*p, *q);
+    }
+}
+
+int main(int argc, char *argv[]) {
+  if (argc != 3) {
+    std::cerr << "Usage " << argv[0] << " ../../../data/meshes/SO3_10000.off 0.3 to load the file " <<
+        "../../data/SO3_10000.off and contract the Rips complex built with paremeter 0.3.\n";
+    return -1;
+  }
+
+  Complex complex;
+
+  // load only the points
+  Gudhi::skeleton_blocker::Skeleton_blocker_off_reader<Complex> off_reader(argv[1], complex, true);
+  if (!off_reader.is_valid()) {
+    std::cerr << "Unable to read file:" << argv[1] << std::endl;
+    return EXIT_FAILURE;
+  }
+
+  std::cout << "Build the Rips complex with " << complex.num_vertices() << " vertices" << std::endl;
+
+  build_rips(complex, atof(argv[2]));
+
+  Gudhi::Clock contraction_chrono("Time to simplify and enumerate simplices");
+
+  std::cout << "Initial complex has " <<
+      complex.num_vertices() << " vertices and " <<
+      complex.num_edges() << " edges" << std::endl;
+
+  Complex_contractor contractor(complex,
+                                new Gudhi::contraction::Edge_length_cost<Profile>,
+                                Gudhi::contraction::make_first_vertex_placement<Profile>(),
+                                Gudhi::contraction::make_link_valid_contraction<Profile>(),
+                                Gudhi::contraction::make_remove_popable_blockers_visitor<Profile>());
+  contractor.contract_edges();
+
+  std::cout << "Counting final number of simplices \n";
+  unsigned num_simplices = std::distance(complex.complex_simplex_range().begin(), complex.complex_simplex_range().end());
+
+  std::cout << "Final complex has " <<
+      complex.num_vertices() << " vertices, " <<
+      complex.num_edges() << " edges, " <<
+      complex.num_blockers() << " blockers and " <<
+      num_simplices << " simplices" << std::endl;
+
+  std::cout << contraction_chrono;
+
+  return EXIT_SUCCESS;
+}
+
+