Multi-Class SVM( one versus all)

Question

I know that LIBSVM only allows one-vs-one classification when it comes to multi-class SVM. However, I would like to tweak it a bit to perform one-against-all classification.

Answer 1

From the code I can see you are trying to first turn the labels into "some class" vs "not this class", and then invoke LibSVM to do training and testing. Some questions and suggestions:

1. Why are you using the original TrainingLabel for training? In my opinion, should it be model = svmtrain(newClass, TrainVec, '-c 1 -g 0.00154');?
2. With modified training mechanism, you also need to tweak the prediction part, such as using sum-pooling to determine the final label. Using -b switch in LibSVM to enable probability output will also improve the accuracy.