append

Appends one or more points to a linestring, ring, polygon, multi-geometry.

Synopsis

template<typename Geometry, typename RangeOrPoint>
void append(Geometry & geometry, RangeOrPoint const & range_or_point, int ring_index = -1, int multi_index = 0)

Parameters

Type	Concept	Name	Description
Geometry &	Any type fulfilling a Geometry Concept	geometry	A model of the specified concept
RangeOrPoint const &	Either a range or a point, fullfilling Boost.Range concept or Boost.Geometry Point Concept	range_or_point	The point or range to add
int		ring_index	The index of the ring in case of a polygon: exterior ring (-1, the default) or interior ring index
int		multi_index	Reserved for multi polygons or multi linestrings

Header

Either

#include <boost/geometry/geometry.hpp>

#include <boost/geometry/algorithms/append.hpp>

Conformance

The function append is not defined by OGC.

Supported geometries

	Point	Range
Point
Segment
Box
Linestring
Ring
Polygon
MultiPoint
MultiLinestring
MultiPolygon

Behavior

Case	Behavior
Point, Rectangle, Segment	Compiles, but no action
Linestring	Appends point or range to the end of the linestring
Ring	Appends point or range to the end of the ring (without explicitly closing it)
Polygon	Appends point or range to the end of the polygon (without explicitly closing it), either the exterior ring (the default) or specify a zero-based index for one of the interior rings. In the last case, the interior rings are not resized automatically, so ensure that the zero-based index is smaller than the number of interior rings

Complexity

Linear

Example

Shows usage of Boost.Geometry's append to append a point or a range to a polygon

#include <iostream>

#include <boost/assign.hpp>

#include <boost/geometry.hpp>
#include <boost/geometry/geometries/polygon.hpp>
#include <boost/geometry/geometries/adapted/boost_tuple.hpp>

BOOST_GEOMETRY_REGISTER_BOOST_TUPLE_CS(cs::cartesian)

int main()
{
    using boost::assign::tuple_list_of;
    using boost::make_tuple;
    using boost::geometry::append;

    typedef boost::geometry::model::polygon<boost::tuple<int, int> > polygon;

    polygon poly;

    // Append a range
    append(poly, tuple_list_of(0, 0)(0, 10)(11, 11)(10, 0)); 
    // Append a point (in this case the closing point)
    append(poly, make_tuple(0, 0));

    // Create an interior ring (append does not do this automatically)
    boost::geometry::interior_rings(poly).resize(1);

    // Append a range to the interior ring
    append(poly, tuple_list_of(2, 2)(2, 5)(6, 6)(5, 2), 0); 
    // Append a point to the first interior ring
    append(poly, make_tuple(2, 2), 0);

    std::cout << boost::geometry::dsv(poly) << std::endl;

    return 0;
}

	tuple_list_of delivers a range and can therefore be used in boost::geometry::append
	The last parameter ring_index 0 denotes the first interior ring

Output:

(((0, 0), (0, 10), (11, 11), (10, 0), (0, 0)), ((2, 2), (2, 5), (6, 6), (5, 2), (2, 2)))

Boost C++ Libraries