// Boost.Geometry (aka GGL, Generic Geometry Library) // QuickBook Example // Copyright (c) 2011-2012 Barend Gehrels, Amsterdam, the Netherlands. // Use, modification and distribution is subject to the Boost Software License, // Version 1.0. (See accompanying file LICENSE_1_0.txt or copy at // http://www.boost.org/LICENSE_1_0.txt) //[boost_range_filtered //` Shows how to use a Boost.Geometry linestring, filtered by Boost.Range adaptor #include <iostream> #include <boost/geometry.hpp> #include <boost/geometry/geometries/linestring.hpp> #include <boost/geometry/geometries/point_xy.hpp> #include <boost/geometry/geometries/adapted/boost_range/filtered.hpp> struct not_two { template <typename P> bool operator()(P const& p) const { return boost::geometry::get<1>(p) != 2; } }; int main() { typedef boost::geometry::model::d2::point_xy<int> xy; boost::geometry::model::linestring<xy> line; line.push_back(xy(0, 0)); line.push_back(xy(1, 1)); line.push_back(xy(2, 2)); line.push_back(xy(3, 1)); line.push_back(xy(4, 0)); line.push_back(xy(5, 1)); line.push_back(xy(6, 2)); line.push_back(xy(7, 1)); line.push_back(xy(8, 0)); using boost::adaptors::filtered; std::cout << boost::geometry::length(line) << std::endl << boost::geometry::length(line | filtered(not_two())) << std::endl << boost::geometry::dsv(line | filtered(not_two())) << std::endl; return 0; } //] //[boost_range_filtered_output /*` Output: [pre 11.3137 9.65685 ((0, 0), (1, 1), (3, 1), (4, 0), (5, 1), (7, 1), (8, 0)) ] */ //]