Question

We are using Java-ML(LibSVM) in order to execute the SVM algorithm over a multi-class problem

        Classifier clas = new LibSVM();
        clas.buildClassifier(data);
        Dataset dataForClassification= FileHandler.loadDataset(new File(.), 0, ",");
        /* Counters for correct and wrong predictions. */
        int correct = 0, wrong = 0;
        /* Classify all instances and check with the correct class values */
        for (Instance inst : dataForClassification) {
            Object predictedClassValue = clas.classify(inst);
            Map<Object,Double> map = clas.classDistribution(inst);
            Object realClassValue = inst.classValue();
            if (predictedClassValue.equals(realClassValue))
                correct++;
            else
                wrong++;
        }

the classDistributtion() returns a standard vector ( meaning all values are 0 but one value which equals to 1)

java-ml – http://java-ml.sourceforge.net/

Answer 1

Despite the other answers, it is possible to output probability estimates for SVMs and LibSVM does do this. However, I’m fairly sure you can’t use this feature from Java-ML. The file LibSVM.java only ever refers to the function svm_predict_values and never svm_predict_probabilities. It probably wouldn’t be too hard to add this functionality in to Java-ML if you felt you really needed it.