root/data/sphere/level_set_test.cpp

DEFINITIONS

1. main
2. check_usage
3. get_vertices
4. convert_to_vertex
5. level_set_function

   1 /*
   2   For a given level set function this program tests the vertices of a dgf file
   3   to see if they are precise enough.
   4 
   5   Created by Christian Power on 11. January 2016.
   6   Copyright (c) 2016 Christian Power.  All rights reserved.
   7  */
   8 
   9 #include <iostream>
  10 #include <fstream>
  11 #include <sstream>
  12 #include <vector>
  13 #include <valarray>
  14 
  15 // cpp 2
  16 // #include <algorithm>
  17 
  18 // cpp 3
  19 // #include <numeric>
  20 // #include <cmath>
  21 
  22 // header 1
  23 void check_usage(int argc, char** argv);
  24 
  25 // header 2
  26 using Vertex = std::valarray<double>;
  27 using Vertices = std::vector<Vertex>;
  28 const Vertices get_vertices(const std::string& filename);
  29 
  30 // cpp 2 -> header 2.1
  31 // const Vertex convert_to_vertex(const std::string& str_vertex);
  32 
  33 // header 3
  34 double level_set_function(const Vertex& vertex);
  35 
  36 int main(int argc, char** argv) try{
  37   check_usage(argc, argv);
  38 
  39   Vertices v_list = get_vertices(argv[1]);
  40 
  41   std::valarray<double> lsf_values (v_list.size());
  42   for(size_t it = 0; it < v_list.size(); ++it)
  43     lsf_values[it] = level_set_function(v_list[it]);
  44 
  45   // std::cout << "All values" << std::endl;
  46   // for(const auto value : lsf_values)
  47   //   std::cout << value << std::endl;
  48   
  49   std::cout << std::scientific;
  50   std::cout << "Mean value: " << lsf_values.sum() / v_list.size() << std::endl;
  51 
  52   std::cout << "Median: ";
  53   std::sort(std::begin(lsf_values), std::end(lsf_values));
  54   if(v_list.size() % 2)
  55     std::cout << lsf_values[ v_list.size()/2 ];
  56   else
  57     std::cout << (lsf_values[ v_list.size()/2 - 1 ] + lsf_values[ v_list.size()/2])/2;
  58   std::cout << std::endl;
  59 }
  60  catch(std::exception& e){
  61    std::cerr << e.what() << '\n';
  62    return 1;
  63  }
  64 
  65 
  66 // cpp 1
  67 void check_usage(int argc, char** argv){
  68   if(argc != 2){
  69     std::ostringstream err_msg;
  70     err_msg << "Usage: " << argv[0] << " filename " << '\n'
  71             << "Program terminating due to invalid input.";
  72     throw std::runtime_error{err_msg.str()};
  73   }
  74 }
  75 
  76 // cpp 2
  77 #include <algorithm>
  78 
  79 const Vertex convert_to_vertex(const std::string& str_vertex);
  80 
  81 const Vertices get_vertices(const std::string& filename){
  82   std::ifstream dgf_file {filename};
  83   if(!dgf_file) throw std::runtime_error {"File \"" + filename + "\" does not exist."};
  84 
  85   std::vector<std::string> lines;
  86   for(std::string line; std::getline(dgf_file,line); )
  87     lines.push_back(line);
  88 
  89   const std::string begin_vertices = "VERTEX";
  90   auto first_it = std::find(std::cbegin(lines), std::cend(lines), begin_vertices);
  91   if(first_it == std::cend(lines))
  92     throw std::runtime_error
  93     {"Could not find " + begin_vertices + " in file \"" + filename + "\"."};
  94   ++first_it;   // skip "VERTEX"
  95   
  96   const std::string end_vertices = "#";
  97   const auto second_it = std::find(first_it, std::cend(lines), end_vertices);
  98   if(second_it == first_it)
  99     throw std::runtime_error
 100     {"Empty vertex list detected in file \"" + filename + "\"."};
 101 
 102   Vertices vertex_list;
 103   int line_no = 1;
 104   for( ; first_it != second_it; ++first_it){
 105     try{
 106       const auto numerical_vertex = convert_to_vertex(*first_it);
 107       vertex_list.push_back(numerical_vertex);
 108     }
 109     catch(const std::exception& e){
 110       std::cerr << e.what() << '\n';
 111       const std::string err_msg {"line" + std::to_string(line_no)};
 112       throw std::runtime_error {err_msg};
 113     }
 114     ++line_no;
 115   }
 116 
 117   return vertex_list;
 118 }
 119 
 120 const Vertex convert_to_vertex(const std::string& str_vertex){
 121   std::istringstream iss {str_vertex};
 122   double d1, d2, d3;
 123   if(!(iss >> d1 >> d2 >> d3) || !(iss >> std::ws).eof() )
 124     throw std::runtime_error {"convert_to_vertex() failed."};
 125   return {d1, d2, d3};
 126 }
 127 
 128 // cpp 3
 129 #include <numeric>
 130 #include <cmath>
 131 
 132 double level_set_function(const Vertex& vertex){
 133   // x**2 + y**2 + z**2 - 1;
 134   using std::begin;
 135   using std::end;
 136   return std::inner_product(begin(vertex), end(vertex), begin(vertex), 0.);
 137 }