Possible bug in QWeighted algorithm

[ekyy2]

Hi,

I am currently running the quick weighted algorithm (both hard and soft) through meka. I find that for certain datasets (for example medical), I get the following error (the type of base classifier does not seem to make a difference):

java.lang.NullPointerException
at weka.classifiers.trees.J48.distributionForInstance(J48.java:279)
at mulan.classifier.transformation.CalibratedLabelRanking.makePredictionQW(CalibratedLabelRanking.java:230)
at mulan.classifier.transformation.CalibratedLabelRanking.makePredictionInternal(CalibratedLabelRanking.java:98)
at mulan.classifier.MultiLabelLearnerBase.makePrediction(MultiLabelLearnerBase.java:113)
at meka.classifiers.multilabel.MULAN.distributionForInstance(MULAN.java:238)
at meka.classifiers.multilabel.Evaluation.testClassifier(Evaluation.java:530)
at meka.classifiers.multilabel.Evaluation.evaluateModel(Evaluation.java:435)
at meka.classifiers.multilabel.Evaluation.evaluateModel(Evaluation.java:326)
at meka.classifiers.multilabel.Evaluation.runExperiment(Evaluation.java:221)
at meka.classifiers.multilabel.ProblemTransformationMethod.runClassifier(ProblemTransformationMethod.java:172)
at meka.classifiers.multilabel.ProblemTransformationMethod.evaluation(ProblemTransformationMethod.java:152)
at meka.classifiers.multilabel.MULAN.main(MULAN.java:248)

I found that this is because a oneVsOneModel may not be built for all label pairs (i.e. noData = true). So when the following statement in the makePredictionQW and makePredictionQWSoft functions in CalibratedLabelRanking.java is made, it triggers the exception because m_root is a null pointer:

double[] distribution = getOneVsOneModels().getModel(modelIndex).distributionForInstance(transformed);

Any advice would be much appreciated. Thanks!

Regards,
Edward