FM / algorithms

/usr/include/boost/geometry/algorithms

Name	Size	Mode	Actions
detail/	-	0755	rm
dispatch/	-	0755	rm
append.hpp	11493	0644	edit dl rm
area.hpp	10657	0644	edit dl rm
assign.hpp	10709	0644	edit dl rm
buffer.hpp	8656	0644	edit dl rm
centroid.hpp	19620	0644	edit dl rm
clear.hpp	5156	0644	edit dl rm
comparable_distance.hpp	1107	0644	edit dl rm
convert.hpp	17327	0644	edit dl rm
convex_hull.hpp	11589	0644	edit dl rm
correct.hpp	9956	0644	edit dl rm
correct_closure.hpp	5862	0644	edit dl rm
covered_by.hpp	1077	0644	edit dl rm
crosses.hpp	8478	0644	edit dl rm
densify.hpp	12472	0644	edit dl rm
difference.hpp	16591	0644	edit dl rm
discrete_frechet_distance.hpp	7844	0644	edit dl rm
discrete_hausdorff_distance.hpp	11281	0644	edit dl rm
disjoint.hpp	1191	0644	edit dl rm
distance.hpp	1110	0644	edit dl rm
envelope.hpp	1021	0644	edit dl rm
equals.hpp	1196	0644	edit dl rm
expand.hpp	1073	0644	edit dl rm
for_each.hpp	9831	0644	edit dl rm
intersection.hpp	806	0644	edit dl rm
intersects.hpp	1145	0644	edit dl rm
is_convex.hpp	6508	0644	edit dl rm
is_empty.hpp	4853	0644	edit dl rm
is_simple.hpp	575	0644	edit dl rm
is_valid.hpp	570	0644	edit dl rm
length.hpp	9341	0644	edit dl rm
line_interpolate.hpp	13054	0644	edit dl rm
make.hpp	5170	0644	edit dl rm
not_implemented.hpp	3839	0644	edit dl rm
num_geometries.hpp	3586	0644	edit dl rm
num_interior_rings.hpp	3756	0644	edit dl rm
num_points.hpp	5565	0644	edit dl rm
num_segments.hpp	4775	0644	edit dl rm
overlaps.hpp	1067	0644	edit dl rm
perimeter.hpp	7212	0644	edit dl rm
point_on_surface.hpp	13281	0644	edit dl rm
relate.hpp	642	0644	edit dl rm
relation.hpp	652	0644	edit dl rm
remove_spikes.hpp	9753	0644	edit dl rm
reverse.hpp	4386	0644	edit dl rm
simplify.hpp	22696	0644	edit dl rm
sym_difference.hpp	23169	0644	edit dl rm
touches.hpp	1127	0644	edit dl rm
transform.hpp	14105	0644	edit dl rm
union.hpp	21383	0644	edit dl rm
unique.hpp	4682	0644	edit dl rm
validity_failure_type.hpp	3684	0644	edit dl rm
within.hpp	1057	0644	edit dl rm

Edit: /usr/include/boost/geometry/algorithms/simplify.hpp (22696B)

// Boost.Geometry (aka GGL, Generic Geometry Library)

// This file was modified by Oracle on 2018.
// Modifications copyright (c) 2018 Oracle and/or its affiliates.

// Contributed and/or modified by Adam Wulkiewicz, on behalf of Oracle

// Parts of Boost.Geometry are redesigned from Geodan's Geographic Library
// (geolib/GGL), copyright (c) 1995-2010 Geodan, 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)

#ifndef BOOST_GEOMETRY_ALGORITHMS_SIMPLIFY_HPP
#define BOOST_GEOMETRY_ALGORITHMS_SIMPLIFY_HPP

#include <cstddef>
#include <set>

#include <boost/core/ignore_unused.hpp>
#include <boost/range.hpp>

#include <boost/variant/apply_visitor.hpp>
#include <boost/variant/static_visitor.hpp>
#include <boost/variant/variant_fwd.hpp>

#include <boost/geometry/core/cs.hpp>
#include <boost/geometry/core/closure.hpp>
#include <boost/geometry/core/exterior_ring.hpp>
#include <boost/geometry/core/interior_rings.hpp>
#include <boost/geometry/core/mutable_range.hpp>
#include <boost/geometry/core/tags.hpp>

#include <boost/geometry/geometries/concepts/check.hpp>
#include <boost/geometry/strategies/agnostic/simplify_douglas_peucker.hpp>
#include <boost/geometry/strategies/concepts/simplify_concept.hpp>
#include <boost/geometry/strategies/default_strategy.hpp>
#include <boost/geometry/strategies/distance.hpp>

#include <boost/geometry/algorithms/area.hpp>
#include <boost/geometry/algorithms/clear.hpp>
#include <boost/geometry/algorithms/convert.hpp>
#include <boost/geometry/algorithms/detail/equals/point_point.hpp>
#include <boost/geometry/algorithms/not_implemented.hpp>
#include <boost/geometry/algorithms/is_empty.hpp>
#include <boost/geometry/algorithms/perimeter.hpp>

#include <boost/geometry/algorithms/detail/distance/default_strategies.hpp>

namespace boost { namespace geometry
{

#ifndef DOXYGEN_NO_DETAIL
namespace detail { namespace simplify
{

template <typename Range, typename EqualsStrategy>
inline bool is_degenerate(Range const& range, EqualsStrategy const& strategy)
{
    return boost::size(range) == 2
        && detail::equals::equals_point_point(geometry::range::front(range),
                                              geometry::range::back(range),
                                              strategy);
}

struct simplify_range_insert
{
    template<typename Range, typename Strategy, typename OutputIterator, typename Distance>
    static inline void apply(Range const& range, OutputIterator out,
                             Distance const& max_distance, Strategy const& strategy)
    {
        typedef typename Strategy::distance_strategy_type::equals_point_point_strategy_type
            equals_strategy_type;

boost::ignore_unused(strategy);

if (is_degenerate(range, equals_strategy_type()))
        {
            std::copy(boost::begin(range), boost::begin(range) + 1, out);
        }
        else if (boost::size(range) <= 2 || max_distance < 0)
        {
            std::copy(boost::begin(range), boost::end(range), out);
        }
        else
        {
            strategy.apply(range, out, max_distance);
        }
    }
};

struct simplify_copy
{
    template <typename RangeIn, typename RangeOut, typename Strategy, typename Distance>
    static inline void apply(RangeIn const& range, RangeOut& out,
                             Distance const& , Strategy const& )
    {
        std::copy
            (
                boost::begin(range), boost::end(range),
                    geometry::range::back_inserter(out)
            );
    }
};

template <std::size_t MinimumToUseStrategy>
struct simplify_range
{
    template <typename RangeIn, typename RangeOut, typename Strategy, typename Distance>
    static inline void apply(RangeIn const& range, RangeOut& out,
                    Distance const& max_distance, Strategy const& strategy)
    {
        typedef typename Strategy::distance_strategy_type::equals_point_point_strategy_type
            equals_strategy_type;

// For a RING:
        // Note that, especially if max_distance is too large,
        // the output ring might be self intersecting while the input ring is
        // not, although chances are low in normal polygons

if (boost::size(range) <= MinimumToUseStrategy || max_distance < 0)
        {
            simplify_copy::apply(range, out, max_distance, strategy);
        }
        else
        {
            simplify_range_insert::apply
                (
                    range, geometry::range::back_inserter(out), max_distance, strategy
                );
        }

// Verify the two remaining points are equal. If so, remove one of them.
        // This can cause the output being under the minimum size
        if (is_degenerate(out, equals_strategy_type()))
        {
            range::resize(out, 1);
        }
    }
};

struct simplify_ring
{
private :
    template <typename Area>
    static inline int area_sign(Area const& area)
    {
        return area > 0 ? 1 : area < 0 ? -1 : 0;
    }

template <typename Strategy, typename Ring>
    static std::size_t get_opposite(std::size_t index, Ring const& ring)
    {
        typename Strategy::distance_strategy_type distance_strategy;

// Verify if it is NOT the case that all points are less than the
        // simplifying distance. If so, output is empty.
        typename Strategy::distance_type max_distance(-1);

typename geometry::point_type<Ring>::type point = range::at(ring, index);
        std::size_t i = 0;
        for (typename boost::range_iterator<Ring const>::type
                it = boost::begin(ring); it != boost::end(ring); ++it, ++i)
        {
            // This actually is point-segment distance but will result
            // in point-point distance
            typename Strategy::distance_type dist = distance_strategy.apply(*it, point, point);
            if (dist > max_distance)
            {
                max_distance = dist;
                index = i;
            }
        }
        return index;
    }

public :
    template <typename Ring, typename Strategy, typename Distance>
    static inline void apply(Ring const& ring, Ring& out,
                    Distance const& max_distance, Strategy const& strategy)
    {
        std::size_t const size = boost::size(ring);
        if (size == 0)
        {
            return;
        }

int const input_sign = area_sign(geometry::area(ring));

std::set<std::size_t> visited_indexes;

// Rotate it into a copied vector
        // (vector, because source type might not support rotation)
        // (duplicate end point will be simplified away)
        typedef typename geometry::point_type<Ring>::type point_type;

std::vector<point_type> rotated(size);

// Closing point (but it will not start here)
        std::size_t index = 0;

// Iterate (usually one iteration is enough)
        for (std::size_t iteration = 0; iteration < 4u; iteration++)
        {
            // Always take the opposite. Opposite guarantees that no point
            // "halfway" is chosen, creating an artefact (very narrow triangle)
            // Iteration 0: opposite to closing point (1/2, = on convex hull)
            //              (this will start simplification with that point
            //               and its opposite ~0)
            // Iteration 1: move a quarter on that ring, then opposite to 1/4
            //              (with its opposite 3/4)
            // Iteration 2: move an eight on that ring, then opposite (1/8)
            // Iteration 3: again move a quarter, then opposite (7/8)
            // So finally 8 "sides" of the ring have been examined (if it were
            // a semi-circle). Most probably, there are only 0 or 1 iterations.
            switch (iteration)
            {
                case 1 : index = (index + size / 4) % size; break;
                case 2 : index = (index + size / 8) % size; break;
                case 3 : index = (index + size / 4) % size; break;
            }
            index = get_opposite<Strategy>(index, ring);

if (visited_indexes.count(index) > 0)
            {
                // Avoid trying the same starting point more than once
                continue;
            }

std::rotate_copy(boost::begin(ring), range::pos(ring, index),
                             boost::end(ring), rotated.begin());

// Close the rotated copy
            rotated.push_back(range::at(ring, index));

simplify_range<0>::apply(rotated, out, max_distance, strategy);

// Verify that what was positive, stays positive (or goes to 0)
            // and what was negative stays negative (or goes to 0)
            int const output_sign = area_sign(geometry::area(out));
            if (output_sign == input_sign)
            {
                // Result is considered as satisfactory (usually this is the
                // first iteration - only for small rings, having a scale
                // similar to simplify_distance, next iterations are tried
                return;
            }

// Original is simplified away. Possibly there is a solution
            // when another starting point is used
            geometry::clear(out);

if (iteration == 0
                && geometry::perimeter(ring) < 3 * max_distance)
            {
                // Check if it is useful to iterate. A minimal triangle has a
                // perimeter of a bit more than 3 times the simplify distance
                return;
            }

// Prepare next try
            visited_indexes.insert(index);
            rotated.resize(size);
        }
    }
};

struct simplify_polygon
{
private:

template
    <
        typename IteratorIn,
        typename InteriorRingsOut,
        typename Distance,
        typename Strategy
    >
    static inline void iterate(IteratorIn begin, IteratorIn end,
                    InteriorRingsOut& interior_rings_out,
                    Distance const& max_distance, Strategy const& strategy)
    {
        typedef typename boost::range_value<InteriorRingsOut>::type single_type;
        for (IteratorIn it = begin; it != end; ++it)
        {
            single_type out;
            simplify_ring::apply(*it, out, max_distance, strategy);
            if (! geometry::is_empty(out))
            {
                range::push_back(interior_rings_out, out);
            }
        }
    }

template
    <
        typename InteriorRingsIn,
        typename InteriorRingsOut,
        typename Distance,
        typename Strategy
    >
    static inline void apply_interior_rings(
                    InteriorRingsIn const& interior_rings_in,
                    InteriorRingsOut& interior_rings_out,
                    Distance const& max_distance, Strategy const& strategy)
    {
        range::clear(interior_rings_out);

iterate(
            boost::begin(interior_rings_in), boost::end(interior_rings_in),
            interior_rings_out,
            max_distance, strategy);
    }

public:
    template <typename Polygon, typename Strategy, typename Distance>
    static inline void apply(Polygon const& poly_in, Polygon& poly_out,
                    Distance const& max_distance, Strategy const& strategy)
    {
        // Note that if there are inner rings, and distance is too large,
        // they might intersect with the outer ring in the output,
        // while it didn't in the input.
        simplify_ring::apply(exterior_ring(poly_in), exterior_ring(poly_out),
            max_distance, strategy);

apply_interior_rings(interior_rings(poly_in),
            interior_rings(poly_out), max_distance, strategy);
    }
};

template<typename Policy>
struct simplify_multi
{
    template <typename MultiGeometry, typename Strategy, typename Distance>
    static inline void apply(MultiGeometry const& multi, MultiGeometry& out,
                    Distance const& max_distance, Strategy const& strategy)
    {
        range::clear(out);

typedef typename boost::range_value<MultiGeometry>::type single_type;

for (typename boost::range_iterator<MultiGeometry const>::type
                it = boost::begin(multi); it != boost::end(multi); ++it)
        {
            single_type single_out;
            Policy::apply(*it, single_out, max_distance, strategy);
            if (! geometry::is_empty(single_out))
            {
                range::push_back(out, single_out);
            }
        }
    }
};

}} // namespace detail::simplify
#endif // DOXYGEN_NO_DETAIL

#ifndef DOXYGEN_NO_DISPATCH
namespace dispatch
{

template
<
    typename Geometry,
    typename Tag = typename tag<Geometry>::type
>
struct simplify: not_implemented<Tag>
{};

template <typename Point>
struct simplify<Point, point_tag>
{
    template <typename Distance, typename Strategy>
    static inline void apply(Point const& point, Point& out,
                    Distance const& , Strategy const& )
    {
        geometry::convert(point, out);
    }
};

// Linestring, keep 2 points (unless those points are the same)
template <typename Linestring>
struct simplify<Linestring, linestring_tag>
    : detail::simplify::simplify_range<2>
{};

template <typename Ring>
struct simplify<Ring, ring_tag>
    : detail::simplify::simplify_ring
{};

template <typename Polygon>
struct simplify<Polygon, polygon_tag>
    : detail::simplify::simplify_polygon
{};

template
<
    typename Geometry,
    typename Tag = typename tag<Geometry>::type
>
struct simplify_insert: not_implemented<Tag>
{};

template <typename Linestring>
struct simplify_insert<Linestring, linestring_tag>
    : detail::simplify::simplify_range_insert
{};

template <typename Ring>
struct simplify_insert<Ring, ring_tag>
    : detail::simplify::simplify_range_insert
{};

template <typename MultiPoint>
struct simplify<MultiPoint, multi_point_tag>
    : detail::simplify::simplify_copy
{};

template <typename MultiLinestring>
struct simplify<MultiLinestring, multi_linestring_tag>
    : detail::simplify::simplify_multi<detail::simplify::simplify_range<2> >
{};

template <typename MultiPolygon>
struct simplify<MultiPolygon, multi_polygon_tag>
    : detail::simplify::simplify_multi<detail::simplify::simplify_polygon>
{};

} // namespace dispatch
#endif // DOXYGEN_NO_DISPATCH

namespace resolve_strategy
{

struct simplify
{
    template <typename Geometry, typename Distance, typename Strategy>
    static inline void apply(Geometry const& geometry,
                             Geometry& out,
                             Distance const& max_distance,
                             Strategy const& strategy)
    {
        dispatch::simplify<Geometry>::apply(geometry, out, max_distance, strategy);
    }

template <typename Geometry, typename Distance>
    static inline void apply(Geometry const& geometry,
                             Geometry& out,
                             Distance const& max_distance,
                             default_strategy)
    {
        typedef typename point_type<Geometry>::type point_type;

typedef typename strategy::distance::services::default_strategy
        <
            point_tag, segment_tag, point_type
        >::type ds_strategy_type;

typedef strategy::simplify::douglas_peucker
        <
            point_type, ds_strategy_type
        > strategy_type;

BOOST_CONCEPT_ASSERT(
            (concepts::SimplifyStrategy<strategy_type, point_type>)
        );

apply(geometry, out, max_distance, strategy_type());
    }
};

struct simplify_insert
{
    template
    <
        typename Geometry,
        typename OutputIterator,
        typename Distance,
        typename Strategy
    >
    static inline void apply(Geometry const& geometry,
                             OutputIterator& out,
                             Distance const& max_distance,
                             Strategy const& strategy)
    {
        dispatch::simplify_insert<Geometry>::apply(geometry, out, max_distance, strategy);
    }

template <typename Geometry, typename OutputIterator, typename Distance>
    static inline void apply(Geometry const& geometry,
                             OutputIterator& out,
                             Distance const& max_distance,
                             default_strategy)
    {
        typedef typename point_type<Geometry>::type point_type;

typedef typename strategy::distance::services::default_strategy
        <
            point_tag, segment_tag, point_type
        >::type ds_strategy_type;

typedef strategy::simplify::douglas_peucker
        <
            point_type, ds_strategy_type
        > strategy_type;

BOOST_CONCEPT_ASSERT(
            (concepts::SimplifyStrategy<strategy_type, point_type>)
        );

apply(geometry, out, max_distance, strategy_type());
    }
};

} // namespace resolve_strategy

namespace resolve_variant {

template <typename Geometry>
struct simplify
{
    template <typename Distance, typename Strategy>
    static inline void apply(Geometry const& geometry,
                             Geometry& out,
                             Distance const& max_distance,
                             Strategy const& strategy)
    {
        resolve_strategy::simplify::apply(geometry, out, max_distance, strategy);
    }
};

template <BOOST_VARIANT_ENUM_PARAMS(typename T)>
struct simplify<boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)> >
{
    template <typename Distance, typename Strategy>
    struct visitor: boost::static_visitor<void>
    {
        Distance const& m_max_distance;
        Strategy const& m_strategy;

visitor(Distance const& max_distance, Strategy const& strategy)
            : m_max_distance(max_distance)
            , m_strategy(strategy)
        {}

template <typename Geometry>
        void operator()(Geometry const& geometry, Geometry& out) const
        {
            simplify<Geometry>::apply(geometry, out, m_max_distance, m_strategy);
        }
    };

template <typename Distance, typename Strategy>
    static inline void
    apply(boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)> const& geometry,
          boost::variant<BOOST_VARIANT_ENUM_PARAMS(T)>& out,
          Distance const& max_distance,
          Strategy const& strategy)
    {
        boost::apply_visitor(
            visitor<Distance, Strategy>(max_distance, strategy),
            geometry,
            out
        );
    }
};

} // namespace resolve_variant

/*!
\brief Simplify a geometry using a specified strategy
\ingroup simplify
\tparam Geometry \tparam_geometry
\tparam Distance A numerical distance measure
\tparam Strategy A type fulfilling a SimplifyStrategy concept
\param strategy A strategy to calculate simplification
\param geometry input geometry, to be simplified
\param out output geometry, simplified version of the input geometry
\param max_distance distance (in units of input coordinates) of a vertex
    to other segments to be removed
\param strategy simplify strategy to be used for simplification, might
    include point-distance strategy

\image html svg_simplify_country.png "The image below presents the simplified country"
\qbk{distinguish,with strategy}
*/
template<typename Geometry, typename Distance, typename Strategy>
inline void simplify(Geometry const& geometry, Geometry& out,
                     Distance const& max_distance, Strategy const& strategy)
{
    concepts::check<Geometry>();

geometry::clear(out);

resolve_variant::simplify<Geometry>::apply(geometry, out, max_distance, strategy);
}

/*!
\brief Simplify a geometry
\ingroup simplify
\tparam Geometry \tparam_geometry
\tparam Distance \tparam_numeric
\note This version of simplify simplifies a geometry using the default
    strategy (Douglas Peucker),
\param geometry input geometry, to be simplified
\param out output geometry, simplified version of the input geometry
\param max_distance distance (in units of input coordinates) of a vertex
    to other segments to be removed

\qbk{[include reference/algorithms/simplify.qbk]}
 */
template<typename Geometry, typename Distance>
inline void simplify(Geometry const& geometry, Geometry& out,
                     Distance const& max_distance)
{
    concepts::check<Geometry>();

geometry::simplify(geometry, out, max_distance, default_strategy());
}

#ifndef DOXYGEN_NO_DETAIL
namespace detail { namespace simplify
{

/*!
\brief Simplify a geometry, using an output iterator
    and a specified strategy
\ingroup simplify
\tparam Geometry \tparam_geometry
\param geometry input geometry, to be simplified
\param out output iterator, outputs all simplified points
\param max_distance distance (in units of input coordinates) of a vertex
    to other segments to be removed
\param strategy simplify strategy to be used for simplification,
    might include point-distance strategy

\qbk{distinguish,with strategy}
\qbk{[include reference/algorithms/simplify.qbk]}
*/
template<typename Geometry, typename OutputIterator, typename Distance, typename Strategy>
inline void simplify_insert(Geometry const& geometry, OutputIterator out,
                            Distance const& max_distance, Strategy const& strategy)
{
    concepts::check<Geometry const>();

resolve_strategy::simplify_insert::apply(geometry, out, max_distance, strategy);
}

/*!
\brief Simplify a geometry, using an output iterator
\ingroup simplify
\tparam Geometry \tparam_geometry
\param geometry input geometry, to be simplified
\param out output iterator, outputs all simplified points
\param max_distance distance (in units of input coordinates) of a vertex
    to other segments to be removed

\qbk{[include reference/algorithms/simplify_insert.qbk]}
 */
template<typename Geometry, typename OutputIterator, typename Distance>
inline void simplify_insert(Geometry const& geometry, OutputIterator out,
                            Distance const& max_distance)
{
    // Concept: output point type = point type of input geometry
    concepts::check<Geometry const>();
    concepts::check<typename point_type<Geometry>::type>();

simplify_insert(geometry, out, max_distance, default_strategy());
}

}} // namespace detail::simplify
#endif // DOXYGEN_NO_DETAIL

}} // namespace boost::geometry

#endif // BOOST_GEOMETRY_ALGORITHMS_SIMPLIFY_HPP

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