ELKI: Implementing a custom ResultHandler

Question

I need to implement a custom ResultHandler but I am confused about how to actually integrate my custom class into the software package.

I have read this: http://elki.dbs.ifi.lmu.de/wiki/HowTo/InvokingELKIFromJava but my question is how are you meant to implement a custom result handler such that it shows up in the GUI?

The only way I can think of doing it is by extracting the elki.jar package and manually inserting my custom class into the source code, and then re-jarring the package. However I am fairly sure this is not the way it is meant to be done.

Also, in my resulthandler I need to output all the rows to a single text file with the cluster that each row belongs to displayed. How tips on how I can achieve this?

Answer 1

There are two questions in here.

1. in order to make your class instantiable by the UIs (both MiniGUI and command line), the classes must implement our Parameterization API. There are essentially two choices to make your class instantiable:

   • Add a public constructor without parameters (the UI won't know how to set your parameters!)
   • Add an inner static class Parameterizer that handles parameterization

2. in order to add your class to autocompletion (dropdown menu), the classes must be discovered by the MiniGUI/CLI/other UIs. ELKI uses two methods of discovery:

   • for .jar files, it reads the META-INF/elki/interfacename service files. This is a classic service-loader approach; except that we also allow ordering instances.
   • for directories only, ELKI will also scan for all .class files, and inspect them. This is mostly meant for development time, to avoid having to update the service files all the time. For performance reasons, we do not inspect the contents of .jar files; these are expected to use service files.

You do not need your class to be in the dropdown menu - you can always type the full class name. If this does not work, adding the name to the service file will not help either, but ELKI can either not find the class at all, or cannot instantiate it.

There is also a tutorial on implementing a custom result handler, but it does not discuss how to add it to the menu. In "development mode" - when having a folder with .class files - it will show up automatically.