| Home | Libraries | People | FAQ | More

##### discrete_frechet_distance

Calculate discrete Frechet distance between two geometries (currently work for LineString-LineString).

###### Synopsis

    template<typename Geometry1, typename Geometry2>
    auto discrete_frechet_distance(Geometry1 const & geometry1, Geometry2 const & geometry2)

###### Parameters

Type | Concept | Name | Description
--- | --- | --- | ---
Geometry1 const & | Any type fulfilling a Geometry Concept | geometry1 | Input geometry
Geometry2 const & | Any type fulfilling a Geometry Concept | geometry2 | Input geometry

###### Header

Either

`#include <boost/geometry.hpp>`

Or

`#include <boost/geometry/algorithms/discrete_frechet_distance.hpp>`

###### Behavior

The algorithm calculate discrete frechet distance between two geometries.

| Note
The units of the distance depends on strategy. In order to change the default behavior a user has to create a strategy and pass it explicitly into the algorithm.

###### Example

Calculate Similarity between two geometries as the discrete frechet distance between them.

    #include <iostream>

    #include <boost/geometry.hpp>
    #include <boost/geometry/geometries/point_xy.hpp>
    #include <boost/geometry/geometries/linestring.hpp>

    int main()
    {
        typedef boost::geometry::model::d2::point_xy<double> point_type;
        typedef boost::geometry::model::linestring<point_type> linestring_type;

        linestring_type ls1, ls2;
        boost::geometry::read_wkt("LINESTRING(0 0,1 1,1 2,2 1,2 2)", ls1);
        boost::geometry::read_wkt("LINESTRING(1 0,0 1,1 1,2 1,3 1)", ls2);

        double res = boost::geometry::discrete_frechet_distance(ls1, ls2);

        std::cout << "Discrete Frechet Distance: " << res << std::endl;

        return 0;
    }

Output:

    Discrete Frechet Distance:  1.41421