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Diffstat (limited to 'src/Gudhi_stat/include/gudhi/Hausdorff_distances.h')
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diff --git a/src/Gudhi_stat/include/gudhi/Hausdorff_distances.h b/src/Gudhi_stat/include/gudhi/Hausdorff_distances.h new file mode 100644 index 00000000..39de764e --- /dev/null +++ b/src/Gudhi_stat/include/gudhi/Hausdorff_distances.h @@ -0,0 +1,149 @@ +/* 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): Pawel Dlotko + * + * Copyright (C) 2015 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/>. + */ + +#ifndef HAUSDORFF_DISTANCES_H +#define HAUSDORFF_DISTANCES_H + +#include <cmath> +#include <limits> +#include <vector> +#include <cstdlib> +#include <iostream> + +namespace Gudhi +{ +namespace Gudhi_stat +{ + + +/** + * This file contains various implementations of Hausrodff distances between collections of points. It contains various implementations that can be used for specific case. +**/ + +/** + * The implementation below works for a case of a metric space given by a distance matrix, and a subspace of a metric space. Our task is to find a Hausdorff distance between the subspace and the whole space. + * The input is a distance matrix (lower triangular part) and a vector of bools indicating a subspace (elementss set to true belongs to the space, the elements set to false do not). +**/ +class Hausdorff_distance_between_subspace_and_the_whole_metric_space +{ +public: + Hausdorff_distance_between_subspace_and_the_whole_metric_space( const std::vector< std::vector<double> >& distance_matrix ):distance_matrix(distance_matrix){} + double operator()( const std::vector< bool >& is_subspace ) + { + double maximal_distance = -std::numeric_limits<double>::max(); + for ( size_t j = 0 ; j != this->distance_matrix.size() ; ++j ) + { + double minimal_distance = std::numeric_limits<double>::max(); + for ( size_t i = 0 ; i != this->distance_matrix.size() ; ++i ) + { + if ( !is_subspace[i] )continue; + double distance = 0; + if ( i < j ) + { + distance = this->distance_matrix[i][j]; + } + else + { + if ( i > j )distance = this->distance_matrix[j][i]; + } + if ( distance > minimal_distance )minimal_distance = distance; + } + if ( maximal_distance < minimal_distance )maximal_distance = minimal_distance; + } + return maximal_distance; + }//Hausdorff_distance_between_subspace_and_the_whole_metric_space + + double operator()( const std::vector< size_t >& subspace , const std::vector< size_t >& space = std::vector< size_t >() ) + { + bool dbg = false; + if ( dbg ) + { + std::cerr << "Calling double operator()( const std::vector< size_t >& subspace , const std::vector< size_t >& space = std::vector< size_t >() ) method \n"; + std::cerr << "subspace.size() : " << subspace.size() << std::endl; + } + double maximal_distance = -std::numeric_limits<double>::max(); + for ( size_t j = 0 ; j != this->distance_matrix.size() ; ++j ) + { + double minimal_distance = std::numeric_limits<double>::max(); + for ( size_t i = 0 ; i != subspace.size() ; ++i ) + { + double distance = 0; + if ( subspace[i] < j ) + { + distance = this->distance_matrix[ j ][ subspace[i] ]; + } + else + { + if ( subspace[i] > j )distance = this->distance_matrix[ subspace[i] ][ j ]; + } + if ( distance < minimal_distance )minimal_distance = distance; + } + if ( maximal_distance < minimal_distance )maximal_distance = minimal_distance; + } + if ( dbg ) + { + std::cerr << "maximal_distance : " << maximal_distance << std::endl; + getchar(); + } + return maximal_distance; + }//Hausdorff_distance_between_subspace_and_the_whole_metric_space +private: + const std::vector< std::vector<double> >& distance_matrix; +}; + +template <typename PointType , typename distanceFunction > +std::vector< std::vector<double> > compute_all_to_all_distance_matrix_between_points( const std::vector< PointType >& points ) +{ + bool dbg = false; + std::vector< std::vector<double> > result; + result.reserve( points.size() ); + distanceFunction f; + for ( size_t i = 0 ; i != points.size() ; ++i ) + { + std::vector<double> this_row; + this_row.reserve( i ); + for ( size_t j = 0 ; j != i ; ++j ) + { + double distance = f( points[i] , points[j] ); + if ( dbg ){std::cerr << "The distance between point : " << i << " and the point : " << j << " is :" << distance << std::endl;} + this_row.push_back( distance ); + } + result.push_back( this_row ); + } + return result; +}//compute_all_to_all_distance_matrix_between_points + +template <typename T> +class identity +{ +public: + T& operator()( T& org ) + { + return org; + } +}; + + +}//namespace Gudhi_stat +}//namespace Gudhi + +#endif |