Quick start

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#### Quick start

    #include <boost/geometry.hpp>
    #include <boost/geometry/geometries/point.hpp>
    #include <boost/geometry/geometries/box.hpp>

    #include <boost/geometry/index/rtree.hpp>

    // to store queries results
    #include <vector>

    // just for output
    #include <iostream>
    #include <boost/foreach.hpp>

    namespace bg = boost::geometry;
    namespace bgi = boost::geometry::index;

    int main()
    {
        typedef bg::model::point<float, 2, bg::cs::cartesian> point;
        typedef bg::model::box<point> box;
        typedef std::pair<box, unsigned> value;

        // create the rtree using default constructor
        bgi::rtree< value, bgi::quadratic<16> > rtree;

        // create some values
        for ( unsigned i = 0 ; i < 10 ; ++i )
        {
            // create a box
            box b(point(i + 0.0f, i + 0.0f), point(i + 0.5f, i + 0.5f));
            // insert new value
            rtree.insert(std::make_pair(b, i));
        }

        // find values intersecting some area defined by a box
        box query_box(point(0, 0), point(5, 5));
        std::vector<value> result_s;
        rtree.query(bgi::intersects(query_box), std::back_inserter(result_s));

        // find 5 nearest values to a point
        std::vector<value> result_n;
        rtree.query(bgi::nearest(point(0, 0), 5), std::back_inserter(result_n));

        // note: in Boost.Geometry WKT representation of a box is polygon

        // display results
        std::cout << "spatial query box:" << std::endl;
        std::cout << bg::wkt<box>(query_box) << std::endl;
        std::cout << "spatial query result:" << std::endl;
        BOOST_FOREACH(value const& v, result_s)
            std::cout << bg::wkt<box>(v.first) << " - " << v.second << std::endl;

        std::cout << "knn query point:" << std::endl;
        std::cout << bg::wkt<point>(point(0, 0)) << std::endl;
        std::cout << "knn query result:" << std::endl;
        BOOST_FOREACH(value const& v, result_n)
            std::cout << bg::wkt<box>(v.first) << " - " << v.second << std::endl;

        return 0;
    }

##### Expected results

    spatial query box:
    POLYGON((0 0,0 5,5 5,5 0,0 0))
    spatial query result:
    POLYGON((0 0,0 0.5,0.5 0.5,0.5 0,0 0)) - 0
    POLYGON((1 1,1 1.5,1.5 1.5,1.5 1,1 1)) - 1
    POLYGON((2 2,2 2.5,2.5 2.5,2.5 2,2 2)) - 2
    POLYGON((3 3,3 3.5,3.5 3.5,3.5 3,3 3)) - 3
    POLYGON((4 4,4 4.5,4.5 4.5,4.5 4,4 4)) - 4
    POLYGON((5 5,5 5.5,5.5 5.5,5.5 5,5 5)) - 5
    knn query point:
    POINT(0 0)
    knn query result:
    POLYGON((4 4,4 4.5,4.5 4.5,4.5 4,4 4)) - 4
    POLYGON((3 3,3 3.5,3.5 3.5,3.5 3,3 3)) - 3
    POLYGON((2 2,2 2.5,2.5 2.5,2.5 2,2 2)) - 2
    POLYGON((0 0,0 0.5,0.5 0.5,0.5 0,0 0)) - 0
    POLYGON((1 1,1 1.5,1.5 1.5,1.5 1,1 1)) - 1