reader_utils.h

 /*    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):       Clément Maria
  *
  *    Copyright (C) 2014  INRIA Sophia Antipolis-Méditerranée (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 GUDHI_READER_UTILS_H
#define GUDHI_READER_UTILS_H

#include <iostream>
#include <fstream>
#include <boost/graph/adjacency_list.hpp>
#include "gudhi/graph_simplicial_complex.h"

inline void
read_points ( std::string file_name
            , std::vector< std::vector< double > > & points)
{  
  std::ifstream in_file (file_name.c_str(),std::ios::in);
  if(!in_file.is_open()) {
    std::cerr << "Unable to open file " << file_name << std::endl;
    return;}

  std::string line;
  double x;
  while( getline ( in_file , line ) )
  {
    std::vector< double > point;
    std::istringstream iss( line );
    while(iss >> x) { point.push_back(x); }
    points.push_back(point);
  }
  in_file.close();
}

inline Graph_t
read_graph ( std::string file_name )
{
  std::ifstream in_ (file_name.c_str(),std::ios::in);
  if(!in_.is_open()) { std::cerr << "Unable to open file " << file_name << std::endl; }

  std::vector< Edge_t >                       edges;
  std::vector< Filtration_value >             edges_fil;
  std::map< Vertex_handle, Filtration_value > vertices;
  
  std::string      line;
  int              dim;
  Vertex_handle    u,v,max_h = -1;
  Filtration_value fil;
  while( getline ( in_ , line ) )
  {
    std::istringstream iss( line );
    while(iss >> dim) {
      switch ( dim ) {
        case 0 : {
          iss >> u; iss >> fil; 
          vertices[u] = fil;
          if(max_h < u) { max_h = u; }
          break;
        }
        case 1 : {
          iss >> u; iss >> v; iss >> fil;
          edges.push_back(Edge_t(u,v));
          edges_fil.push_back(fil);
          break;
        }
        default: {break;} 
      } 
    }
  }
  in_.close();

  if((size_t)(max_h+1) != vertices.size())
    { std::cerr << "Error: vertices must be labeled from 0 to n-1 \n"; }

  Graph_t skel_graph(edges.begin(),edges.end(),edges_fil.begin(),vertices.size());
  auto vertex_prop = boost::get(vertex_filtration_t(),skel_graph);

  boost::graph_traits<Graph_t>::vertex_iterator vi, vi_end;
  auto v_it = vertices.begin();
  for (tie(vi, vi_end) = boost::vertices(skel_graph); vi != vi_end; ++vi,++v_it)
  { boost::put(vertex_prop, *vi, v_it->second); }

  return skel_graph;
}

template< typename Vertex_handle
        , typename Filtration_value >
bool read_simplex ( std::istream                 & in_                     
                  , std::vector< Vertex_handle > & simplex
                  , Filtration_value             & fil )
{
  int dim=0;
  if(!(in_ >> dim)) return false;
  Vertex_handle v;
  for(int i=0; i<dim+1; ++i)
  { in_ >> v; simplex.push_back(v); }
  in_ >> fil;
  in_.ignore((std::numeric_limits<std::streamsize>::max)(), '\n'); // ignore until the carriage return
  return true;
}

template< typename Simplex_key
        , typename Filtration_value >
bool read_hasse_simplex ( std::istream                 & in_  
                        , std::vector< Simplex_key >   & boundary
                        , Filtration_value             & fil )
{
  int dim;
  if(!(in_ >> dim)) return false;
  if(dim == 0) {in_ >> fil; return true;}
  Simplex_key key;
  for(int i=0; i<dim+1; ++i) 
  { in_ >> key; boundary.push_back(key); }
  in_ >> fil;
  return true;
}

#endif // GUDHI_READER_UTILS_H