How to use DimensionSelectingLatLngDistanceFunction in ELKI

Question

Does anyone know how I am supposed to use the DimensionSelectingLatLngDistanceFunction in ELKI?

When try to use it I get Constraint: distance.latitudedim >= 0.

but what is -distance.latitudedim exactly? Does it let me specify meters instead of degrees maybe? But how do I do that? When I look in the code I can see it's an integer..

Answer 1

ELKI parameters have a documentation. You can find it in command line help (using -help or -description <classname>), or in the tooltips of the MiniGUI. I have to gree that the MiniGUI could make this easier accessible, but I'm not very good at UI design, and the UI is completely generic, generated programmatically from the available parameters.

The following is the output of command line ELKI,

java -jar elki.jar KDDCLIApplication -description
de.lmu.ifi.dbs.elki.distance.distancefunction.geo.DimensionSelectingLatLngDistanceFunction

which yields the parameter explanation:

Description for class
de.lmu.ifi.dbs.elki.distance.distancefunction.geo.DimensionSelectingLatLngDistanceFunction
DimensionSelectingLatLngDistanceFunction
-distance.latitudedim <int>
    The dimension containing the latitude.
    Constraint: distance.latitudedim >= 0.
-distance.longitudedim <int>
    The dimension containing the longitude.
    Constraint: distance.longitudedim >= 0.
-geo.model <class|object>
    Earth model to use for projection. Default: spherical model.
    Implementing de.lmu.ifi.dbs.elki.math.geodesy.EarthModel
    Known classes (default package de.lmu.ifi.dbs.elki.math.geodesy):
    -> SphericalHaversineEarthModel
    -> SphericalVincentyEarthModel
    -> SphericalCosineEarthModel
    -> WGS84SpheroidEarthModel
    -> GRS80SpheroidEarthModel
    -> WGS72SpheroidEarthModel
    -> GRS67SpheroidEarthModel
    -> Clarke1880SpheroidEarthModel
    -> Clarke1858SpheroidEarthModel
    Default: SphericalVincentyEarthModel

The short explanation is: it's te attribute numbers (starting at 0, integer, and non-negative) containing the latitude and longitude within each vector. So if your CSV file has columns

shoe-size latitude random-number longitude weight

then you'd use -distance.latitudedim 1 -distance.longitudedim 3.