Boost C++ Libraries

...one of the most highly regarded and expertly designed C++ library projects in the world. Herb Sutter and Andrei Alexandrescu, C++ Coding Standards

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Boost.Range filtered

Boost.Range filtered range adaptor is adapted to Boost.Geometry

Description

Boost.Range filtered range adaptor filters a range.

Model of

The Boost.Range filtered range adaptor takes over the model of the original geometry, which might be:

Header

#include <boost/geometry/geometries/adapted/boost_range/filtered.hpp>

The standard header boost/geometry.hpp does not include this header.

Example

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;
}

Output:

11.3137
9.65685
((0, 0), (1, 1), (3, 1), (4, 0), (5, 1), (7, 1), (8, 0))

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