How to count up an error in svm

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Josef
Josef on 23 Oct 2013
Commented: Ilya on 28 Oct 2013
Hello, I'm using 'svmtrain' in MATLAB R2013a and I'm looking for function counting a training error.
I drew a picture where data are separated by the classifier, but there is one red dot in wrong side and that's the error I mean...
So how can i count it up??
Thanks

Accepted Answer

Ilya
Ilya on 24 Oct 2013
Classification error by definition is the fraction of misclassified observations. So if you have one misclassified point, divide 1 by the number of observations in your data.
Take a look at 'help confusionmat' or 'doc confusionmat'.
  9 Comments
Ilya
Ilya on 28 Oct 2013
I have never seen anyone trying to estimate the geometric margin for non-linear SVM. The geometric margin is only used in textbooks for pedagogical reasons, using the picture just like the one you've attached.
The margin defined as y*f for class label y in set {-1,+1} and soft score f is a useful concept in the learning theory. But that's not what you want.
I suspect you are somewhat confused about what you really want to compute. Either that or I have no idea what you are doing.

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