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Diffstat (limited to 'example/Witness_complex/example_witness_complex_persistence.cpp')
| -rw-r--r-- | example/Witness_complex/example_witness_complex_persistence.cpp | 171 |
1 files changed, 171 insertions, 0 deletions
diff --git a/example/Witness_complex/example_witness_complex_persistence.cpp b/example/Witness_complex/example_witness_complex_persistence.cpp new file mode 100644 index 00000000..a1146922 --- /dev/null +++ b/example/Witness_complex/example_witness_complex_persistence.cpp @@ -0,0 +1,171 @@ +/* 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): Siargey Kachanovich + * + * Copyright (C) 2016 INRIA (France) + * + * 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/Simplex_tree.h> +#include <gudhi/Euclidean_witness_complex.h> +#include <gudhi/Persistent_cohomology.h> +#include <gudhi/Points_off_io.h> +#include <gudhi/pick_n_random_points.h> + +#include <boost/program_options.hpp> + +#include <CGAL/Epick_d.h> + +#include <string> +#include <vector> +#include <limits> // infinity + +using K = CGAL::Epick_d<CGAL::Dynamic_dimension_tag>; +using Point_d = K::Point_d; + +using Point_vector = std::vector<Point_d>; +using Witness_complex = Gudhi::witness_complex::Euclidean_witness_complex<K>; +using SimplexTree = Gudhi::Simplex_tree<>; + +using Filtration_value = SimplexTree::Filtration_value; + +using Field_Zp = Gudhi::persistent_cohomology::Field_Zp; +using Persistent_cohomology = Gudhi::persistent_cohomology::Persistent_cohomology<SimplexTree, Field_Zp>; + +void program_options(int argc, char * argv[] + , int & nbL + , std::string & file_name + , std::string & filediag + , Filtration_value & max_squared_alpha + , int & p + , int & dim_max + , Filtration_value & min_persistence); + +int main(int argc, char * argv[]) { + std::string file_name; + std::string filediag; + Filtration_value max_squared_alpha; + int p, nbL, lim_d; + Filtration_value min_persistence; + SimplexTree simplex_tree; + + program_options(argc, argv, nbL, file_name, filediag, max_squared_alpha, p, lim_d, min_persistence); + + // Extract the points from the file file_name + Point_vector witnesses, landmarks; + Gudhi::Points_off_reader<Point_d> off_reader(file_name); + if (!off_reader.is_valid()) { + std::cerr << "Witness complex - Unable to read file " << file_name << "\n"; + exit(-1); // ----- >> + } + witnesses = Point_vector(off_reader.get_point_cloud()); + std::cout << "Successfully read " << witnesses.size() << " points.\n"; + std::cout << "Ambient dimension is " << witnesses[0].dimension() << ".\n"; + + // Choose landmarks from witnesses + Gudhi::subsampling::pick_n_random_points(witnesses, nbL, std::back_inserter(landmarks)); + + // Compute witness complex + Witness_complex witness_complex(landmarks, + witnesses); + + witness_complex.create_complex(simplex_tree, max_squared_alpha, lim_d); + + std::cout << "The complex contains " << simplex_tree.num_simplices() << " simplices \n"; + std::cout << " and has dimension " << simplex_tree.dimension() << " \n"; + + // Sort the simplices in the order of the filtration + simplex_tree.initialize_filtration(); + + // Compute the persistence diagram of the complex + Persistent_cohomology pcoh(simplex_tree); + // initializes the coefficient field for homology + pcoh.init_coefficients(p); + + pcoh.compute_persistent_cohomology(min_persistence); + + // Output the diagram in filediag + if (filediag.empty()) { + pcoh.output_diagram(); + } else { + std::ofstream out(filediag); + pcoh.output_diagram(out); + out.close(); + } + + return 0; +} + + +void program_options(int argc, char * argv[] + , int & nbL + , std::string & file_name + , std::string & filediag + , Filtration_value & max_squared_alpha + , int & p + , int & dim_max + , Filtration_value & min_persistence) { + namespace po = boost::program_options; + + po::options_description hidden("Hidden options"); + hidden.add_options() + ("input-file", po::value<std::string>(&file_name), + "Name of file containing a point set in off format."); + + Filtration_value default_alpha = std::numeric_limits<Filtration_value>::infinity(); + po::options_description visible("Allowed options", 100); + visible.add_options() + ("help,h", "produce help message") + ("landmarks,l", po::value<int>(&nbL), + "Number of landmarks to choose from the point cloud.") + ("output-file,o", po::value<std::string>(&filediag)->default_value(std::string()), + "Name of file in which the persistence diagram is written. Default print in std::cout") + ("max-sq-alpha,a", po::value<Filtration_value>(&max_squared_alpha)->default_value(default_alpha), + "Maximal squared relaxation parameter.") + ("field-charac,p", po::value<int>(&p)->default_value(11), + "Characteristic p of the coefficient field Z/pZ for computing homology.") + ("min-persistence,m", po::value<Filtration_value>(&min_persistence)->default_value(0), + "Minimal lifetime of homology feature to be recorded. Default is 0. Enter a negative value to see zero length intervals") + ("cpx-dimension,d", po::value<int>(&dim_max)->default_value(std::numeric_limits<int>::max()), + "Maximal dimension of the weak witness complex we want to compute."); + + 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 a Weak witness 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(); + } +} |