svm - LibSVM one class classification nu parameter is not a fraction of outliers? -
Please correct me if I am wrong, but a class SVM principle states that nu parameter upper bound (UB) training Outliers in Datasets and LBs of the number of SVs say that I am using RBF Gaussian Kernel, so considering the nu parameter, no matter what the value of gamma I choose, the result of the model Be able to generate Is there a UB outlayer dataset in parameter NU training? However, it is not what I have seen that I have seen using a few simple examples with LbsM in Little:
[heart_scale_label, heart_scale_inst] = libsvmread ('.. / heart_scale') ; Ind_good = (heart_scale_label == 1); Heart_scale_label = heart_scale_label (ind_good); Heart_scale_inst = heart_scale_inst (ind_good); Train_data = heart_scale_inst; Train_label = heart_scale_label; Gamma = 0.01; New = 0.01; Model = svmtrain (train_label, train_data, ['-s 2 -t 2 -n' num2str (nu) '-g' num2str (gamma) '-h 0']); [Predict_label_Tr, accuracy_tr, dec_values_Tr] = svmpredict (train_label, train_data, model); Accuracy by using Gamma = 0.01 TAGR = <0.01> I get the accuracy of trained data using 97.50 / gamma = 100. I get the accuracy of training data as 42.50 only when the only part of the outliers in training dataset, Is selected?
Actually I discovered the same problem. The performance of SVM generally depends on the contact of γ and nu. If you are fixing a parameter while trying to tune each other, then there is not even one in the learning curve.
I have to draw training accuracy, accuracy test (5 times in depth of heart), and three images on their difference. From γ to 10 ^ (- 4) to 10 ^ (1) , and nu from 10 ^ (- 3) to to < Code> 10 ^ (- 1) :
To observe the small parameters more clearly, I applied logarithm to γ and New axis, see the following figure:
In fact, looks more clearly than with the given 120 data.
Not quite clear or not perfect at all! Generalization on parameters seems a bit smoother as the dependence of the error, possibly due to the optimization algorithm used in Libsevim instead of 'true' solution ...
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