Accord KDTree with custom distance function

Question

I have a graph data structure representing a road network (nodes are points / intersections on the road and edges are roads). A Node object has latitude and longitude associated with it.

I use the Accord KDTree class to find the nearest nodes for a given GPS coordinate. Since Accord doesn't seem to have Haversine distance as a built-in distance function (am I mistaken?), I define my own distance function and pass it as an additional parameter to the KDTree.FromData () method as follows:

        var nodes = graph.Nodes;
        //Initialize KD-tree with distance function defined as the cartesian approximate distance (in meters) 
        Func<double[], double[], double> distanceFunc = (x, y) => DistanceFunctions.ApproximateDistance(x,y);
        kdTreeOfNodes = KDTree.FromData<Node>(nodes.Select(x => new double[] { x.Value.Latitude, x.Value.Longitude }).ToArray(), nodes.ToArray(), distanceFunc);

Note that "ApproximateDistance" is defined as a static method in a separate class and is a Cartesian approximation to the more correct Haversin distance.

I get an exception when trying to break the last line. On this line, I pass the data to be placed in KDTree (namely an array of lat / lon arrays), as well as related nodes, as well as my custom distance function. It looks like this FromData constructor actually (for some reason?) Calls my ApproximateDistance function, and arrays [1] and [1] as two input parameters, explicitly raising the exception, since this method expects two two-dimensional arrays.

I have no idea why this constructor calls my ApproximateDistance function (especially with these strange parameters), and it can't seem like it has detected the use of a debugger ...

Answer 1

K-d- , .

. , .

k-d- , .

Answer 2

Kd Accord.NET "", (.. . Nearest ApproximateNearest). -, K-d , , .

, , ApproximateDistance , , .

, , , , .

, , , Vantage -Point-.

: k-d Accord.NET.