1 files changed, 117 insertions, 0 deletions
diff --git a/example/Persistent_cohomology/alpha_complex_persistence.cpp b/example/Persistent_cohomology/alpha_complex_persistence.cpp
new file mode 100644
index 00000000..cb181936
--- /dev/null
+++ b/example/Persistent_cohomology/alpha_complex_persistence.cpp
@@ -0,0 +1,117 @@
+#include <boost/program_options.hpp>
+
+#include <CGAL/Epick_d.h>
+
+#include <gudhi/Alpha_complex.h>
+#include <gudhi/Persistent_cohomology.h>
+
+#include <iostream>
+#include <string>
+#include <limits>  // for numeric_limits
+
+void program_options(int argc, char * argv[]
+                     , std::string & off_file_points
+                     , std::string & output_file_diag
+                     , Filtration_value & alpha_square_max_value
+                     , int & coeff_field_characteristic
+                     , Filtration_value & min_persistence);
+
+int main(int argc, char **argv) {
+  std::string off_file_points;
+  std::string output_file_diag;
+  Filtration_value alpha_square_max_value;
+  int coeff_field_characteristic;
+  Filtration_value min_persistence;
+
+  program_options(argc, argv, off_file_points, output_file_diag, alpha_square_max_value,
+                  coeff_field_characteristic, min_persistence);
+
+  // ----------------------------------------------------------------------------
+  // Init of an alpha complex from an OFF file
+  // ----------------------------------------------------------------------------
+  using Kernel = CGAL::Epick_d< CGAL::Dynamic_dimension_tag >;
+  Gudhi::alpha_complex::Alpha_complex<Kernel> alpha_complex_from_file(off_file_points, alpha_square_max_value);
+
+  // ----------------------------------------------------------------------------
+  // Display information about the alpha complex
+  // ----------------------------------------------------------------------------
+  std::cout << "Alpha complex is of dimension " << alpha_complex_from_file.dimension() <<
+      " - " << alpha_complex_from_file.num_simplices() << " simplices - " <<
+      alpha_complex_from_file.num_vertices() << " vertices." << std::endl;
+
+  // Sort the simplices in the order of the filtration
+  alpha_complex_from_file.initialize_filtration();
+
+  std::cout << "Simplex_tree dim: " << alpha_complex_from_file.dimension() << std::endl;
+  // Compute the persistence diagram of the complex
+  Gudhi::persistent_cohomology::Persistent_cohomology< Gudhi::alpha_complex::Alpha_complex<Kernel>,
+      Gudhi::persistent_cohomology::Field_Zp > pcoh(alpha_complex_from_file);
+  // initializes the coefficient field for homology
+  pcoh.init_coefficients(coeff_field_characteristic);
+
+  pcoh.compute_persistent_cohomology(min_persistence);
+
+  // Output the diagram in filediag
+  if (output_file_diag.empty()) {
+    pcoh.output_diagram();
+  } else {
+    std::cout << "Result in file: " << output_file_diag << std::endl;
+    std::ofstream out(output_file_diag);
+    pcoh.output_diagram(out);
+    out.close();
+  }
+
+  return 0;
+}
+
+void program_options(int argc, char * argv[]
+                     , std::string & off_file_points
+                     , std::string & output_file_diag
+                     , Filtration_value & alpha_square_max_value
+                     , int & coeff_field_characteristic
+                     , Filtration_value & min_persistence) {
+  namespace po = boost::program_options;
+  po::options_description hidden("Hidden options");
+  hidden.add_options()
+      ("input-file", po::value<std::string>(&off_file_points),
+       "Name of file containing a point set. Format is one point per line:   X1 ... Xd ");
+
+  po::options_description visible("Allowed options", 100);
+  visible.add_options()
+      ("help,h", "produce help message")
+      ("output-file,o", po::value<std::string>(&output_file_diag)->default_value(std::string()),
+       "Name of file in which the persistence diagram is written. Default print in std::cout")
+      ("max-alpha-square-value,r",
+      po::value<Filtration_value>(&alpha_square_max_value)->default_value(std::numeric_limits<Filtration_value>::infinity()),
+       "Maximal alpha square value for the Alpha complex construction.")
+      ("field-charac,p", po::value<int>(&coeff_field_characteristic)->default_value(11),
+       "Characteristic p of the coefficient field Z/pZ for computing homology.")
+      ("min-persistence,m", po::value<Filtration_value>(&min_persistence),
+       "Minimal lifetime of homology feature to be recorded. Default is 0. Enter a negative value to see zero length intervals");
+
+  po::positional_options_description pos;
+  pos.add("input-file", 1);
+
+  po::options_description all;
+  all.add(visible).add(hidden);
+
+  po::variables_map vm;
+  po::store(po::command_line_parser(argc, argv).
+            options(all).positional(pos).run(), vm);
+  po::notify(vm);
+
+  if (vm.count("help") || !vm.count("input-file")) {
+    std::cout << std::endl;
+    std::cout << "Compute the persistent homology with coefficient field Z/pZ \n";
+    std::cout << "of an Alpha complex defined on a set of input points.\n \n";
+    std::cout << "The output diagram contains one bar per line, written with the convention: \n";
+    std::cout << "   p   dim b d \n";
+    std::cout << "where dim is the dimension of the homological feature,\n";
+    std::cout << "b and d are respectively the birth and death of the feature and \n";
+    std::cout << "p is the characteristic of the field Z/pZ used for homology coefficients." << std::endl << std::endl;
+
+    std::cout << "Usage: " << argv[0] << " [options] input-file" << std::endl << std::endl;
+    std::cout << visible << std::endl;
+    std::abort();
+  }
+}