Introduction

Introduction#

As of version 3.4.4 it is possible for WEKA to dynamically discover classes at runtime (rather than using only those specified in the GenericObjectEditor.props (GOE) file).

If dynamic class discovery is too slow, e.g., due to an enormous CLASSPATH, you can generate a new GenericObjectEditor.props file and then turn dynamic class discovery off. It is assumed that you already placed the GenericPropertiesCreator.props (GPC) file in your home directory (this file is located in directory weka/gui of either the weka.jar or weka-src.jar ZIP archive) and that the weka.jar jar archive with the WEKA classes is in your CLASSPATH (otherwise you have to add it to the java call using the -classpath option).

For generating the GOE file, execute the following steps:

generate a new GenericObjectEditor.props file using the following command:
- Linux/Unix
  
  java weka.gui.GenericPropertiesCreator \ $HOME/GenericPropertiesCreator.props \ $HOME/GenericObjectEditor.props
- Windows (command must be in one line)
  
  java weka.gui.GenericPropertiesCreator %USERPROFILE%\GenericPropertiesCreator.props %USERPROFILE%\GenericObjectEditor.props
edit the GenericPropertiesCreator.props file in your home directory and set UseDynamic to false.

For disabling dynamic class discovery, you need to set the boolean constant USE_DYNAMIC of the weka.gui.GenericObjectEditor class to false. See article Compiling WEKA for more information on how to compile a modified version of WEKA.

A limitation of the GOE prior to 3.4.4 was, that additional classifiers, filters, etc., had to fit into the same package structure as the already existing ones, i.e., all had to be located below weka. WEKA can now display multiple class hierarchies in the GUI, which makes adding new functionality quite easy as we will see later in an example (it is not restricted to classifiers only, but also works with all the other entries in the GPC file).

File Structure#

The structure of the GOE so far was a key-value-pair, separated by an equals-sign. The value is a comma separated list of classes that are all derived from the superclass/superinterface key. The GPC is slightly different, instead of declaring all the classes/interfaces one need only to specify all the packages descendants are located in (only non-abstract ones are then listed). E.g., the weka.classifiers.Classifier entry in the GOE file looks like this:

 weka.classifiers.Classifier=\
  weka.classifiers.bayes.AODE,\
  weka.classifiers.bayes.BayesNet,\
  weka.classifiers.bayes.ComplementNaiveBayes,\
  weka.classifiers.bayes.NaiveBayes,\
  weka.classifiers.bayes.NaiveBayesMultinomial,\
  weka.classifiers.bayes.NaiveBayesSimple,\
  weka.classifiers.bayes.NaiveBayesUpdateable,\
  weka.classifiers.functions.LeastMedSq,\
  weka.classifiers.functions.LinearRegression,\
  weka.classifiers.functions.Logistic,\
  ...

The entry producing the same output for the classifiers in the GPC looks like this (7 lines instead of over 70!):

 weka.classifiers.Classifier=\
  weka.classifiers.bayes,\
  weka.classifiers.functions,\
  weka.classifiers.lazy,\
  weka.classifiers.meta,\
  weka.classifiers.trees,\
  weka.classifiers.rules

Class Discovery#

Unlike the Class.forName(String) method that grabs the first class it can find in the CLASSPATH, and therefore fixes the location of the package it found the class in, the dynamic discovery examines the complete CLASSPATH you're starting the Java Virtual Machine (JVM) with. This means that you can have several parallel directories with the same WEKA package structure, e.g. the standard release of WEKA in one directory ( /distribution/weka.jar) and another one with your own classes (/development/weka/...), and display all of the classifiers in the GUI. In case of a name conflict, i.e. two directories contain the same class, the first one that can be found is used. In a nutshell, your java call of the GUIChooser could look like this:

 java -classpath "/development:/distribution/weka.jar" weka.gui.GUIChooser

Note: Windows users have to replace the ":" with ";" and the forward slashes with backslashes.

Multiple Class Hierarchies#

In case you're developing your own framework, but still want to use your classifiers within WEKA that wasn't possible so far. With the release 3.4.4 it is possible to have multiple class hierarchies being displayed in the GUI. If you've developed a modified version of J48, let's call it MyJ48 and it's located in the package dummy.classifiers then you'll have to add this package to the classifiers list in the GPC file like this:

 weka.classifiers.Classifier=\
  weka.classifiers.bayes,\
  weka.classifiers.functions,\
  weka.classifiers.lazy,\
  weka.classifiers.meta,\
  weka.classifiers.trees,\
  weka.classifiers.rules,\
  dummy.classifiers

Your java call for the GUIChooser might look like this:

 java -classpath "weka.jar:dummy.jar" weka.gui.GUIChooser