1 files changed, 70 insertions, 0 deletions
diff --git a/src/Witness_complex/example/example_witness_complex_sphere.cpp b/src/Witness_complex/example/example_witness_complex_sphere.cpp
new file mode 100644
index 00000000..9e3c972d
--- /dev/null
+++ b/src/Witness_complex/example/example_witness_complex_sphere.cpp
@@ -0,0 +1,70 @@
+#define BOOST_PARAMETER_MAX_ARITY 12
+
+#include <gudhi/Simplex_tree.h>
+#include <gudhi/Euclidean_witness_complex.h>
+#include <gudhi/pick_n_random_points.h>
+#include <gudhi/choose_n_farthest_points.h>
+#include <gudhi/reader_utils.h>
+
+#include <CGAL/Epick_d.h>
+
+#include <iostream>
+#include <fstream>
+#include <ctime>
+#include <utility>
+#include <string>
+#include <vector>
+
+#include "generators.h"
+
+/** Write a gnuplot readable file.
+ *  Data range is a random access range of pairs (arg, value)
+ */
+template <typename Data_range>
+void write_data(Data_range& data, std::string filename) {
+  std::ofstream ofs(filename, std::ofstream::out);
+  for (auto entry : data) ofs << entry.first << ", " << entry.second << "\n";
+  ofs.close();
+}
+
+int main(int argc, char* const argv[]) {
+  using Kernel = CGAL::Epick_d<CGAL::Dynamic_dimension_tag>;
+  using Witness_complex = Gudhi::witness_complex::Euclidean_witness_complex<Kernel>;
+
+  if (argc != 2) {
+    std::cerr << "Usage: " << argv[0] << " number_of_landmarks \n";
+    return 0;
+  }
+
+  int number_of_landmarks = atoi(argv[1]);
+
+  std::vector<std::pair<int, double> > l_time;
+
+  // Generate points
+  for (int nbP = 500; nbP < 10000; nbP += 500) {
+    clock_t start, end;
+    // Construct the Simplex Tree
+    Gudhi::Simplex_tree<> simplex_tree;
+    Point_Vector point_vector, landmarks;
+    generate_points_sphere(point_vector, nbP, 4);
+    std::cout << "Successfully generated " << point_vector.size() << " points.\n";
+    std::cout << "Ambient dimension is " << point_vector[0].size() << ".\n";
+
+    // Choose landmarks
+    start = clock();
+    // Gudhi::subsampling::pick_n_random_points(point_vector, number_of_landmarks, std::back_inserter(landmarks));
+    Gudhi::subsampling::choose_n_farthest_points(K(), point_vector, number_of_landmarks,
+                                                 Gudhi::subsampling::random_starting_point,
+                                                 std::back_inserter(landmarks));
+
+    // Compute witness complex
+    Witness_complex witness_complex(landmarks, point_vector);
+    witness_complex.create_complex(simplex_tree, 0);
+    end = clock();
+    double time = static_cast<double>(end - start) / CLOCKS_PER_SEC;
+    std::cout << "Witness complex for " << number_of_landmarks << " landmarks took " << time << " s. \n";
+    std::cout << "Number of simplices is: " << simplex_tree.num_simplices() << "\n";
+    l_time.push_back(std::make_pair(nbP, time));
+  }
+  write_data(l_time, "w_time.dat");
+}