16.2 Conventions for Implementing Classifiers 555 In weka.core there are many other useful interfaces for classifiers--for example, interfaces for classifiers that are randomizable, summarizable, drawable, and graph able. For more information on these and other interfaces, look at the Javadoc for the classes in weka.core. 16.2 CONVENTIONSFORIMPLEMENTINGCLASSIFIERS There are some conventions that you must obey when implementing classifiers in Weka. If you do not, things will go awry. For example, Weka's evaluation module might not compute the classifier's statistics properly when evaluating it. The Check Classifier class can be used to check the basic behavior of a classifier, although it cannot catch all problems. The first convention has already been mentioned: Each time a classifier's build Classifier() method is called, it must reset the model. The CheckClassifier class performs tests to ensure that this is the case. When buildClassifier() is called on a dataset, the same result must always be obtained regardless of how often the classi- fier has previously been applied to the same or other datasets. However, build