ceph/src/boost/libs/geometry/doc/src/examples/algorithms/comparable_distance.cpp

   1 // Boost.Geometry (aka GGL, Generic Geometry Library)
   2 // QuickBook Example
   3
   4 // Copyright (c) 2011-2012 Barend Gehrels, Amsterdam, the Netherlands.
   5
   6 // Use, modification and distribution is subject to the Boost Software License,
   7 // Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at
   8 // http://www.boost.org/LICENSE_1_0.txt)
   9
  10 //[comparable_distance
  11 //` Shows how to efficiently get the closest point
  12
  13 #include <iostream>
  14
  15 #include <boost/geometry.hpp>
  16 #include <boost/geometry/geometries/point_xy.hpp>
  17
  18 #include <boost/numeric/conversion/bounds.hpp>
  19 #include <boost/foreach.hpp>
  20
  21 int main()
  22 {
  23     typedef boost::geometry::model::d2::point_xy<double> point_type;
  24
  25     point_type p(1.4, 2.6);
  26
  27     std::vector<point_type> v;
  28     for (double x = 0.0; x <= 4.0; x++)
  29     {
  30         for (double y = 0.0; y <= 4.0; y++)
  31         {
  32             v.push_back(point_type(x, y));
  33         }
  34     }
  35
  36     point_type min_p;
  37     double min_d = boost::numeric::bounds<double>::highest();
  38     BOOST_FOREACH(point_type const& pv, v)
  39     {
  40         double d = boost::geometry::comparable_distance(p, pv);
  41         if (d < min_d)
  42         {
  43             min_d = d;
  44             min_p = pv;
  45         }
  46     }
  47
  48     std::cout
  49         << "Closest: " << boost::geometry::dsv(min_p) << std::endl
  50         << "At: " << boost::geometry::distance(p, min_p) << std::endl;
  51
  52     return 0;
  53 }
  54
  55 //]
  56
  57
  58 //[comparable_distance_output
  59 /*`
  60 Output:
  61 [pre
  62 Closest: (1, 3)
  63 At: 0.565685
  64 ]
  65 */
  66 //]
  67