Hi, I'm learning more about SVMs and kernels in general. I've gotten used to using the svm function in the e1071 package. It works great. Now, I want to do/learn some more interesting stuff. (Perhaps my own kernel and/or scoring system). So I want to better understand 1) how calculation of the kernel happens. 2) how to calculate the predicted value (y_hat) given a list of support vectors and coefficients. I've seen all the formulas and many of the books. I get most of it conceptually. Where I'm having trouble is making the leap from concept to actual use. Ideally, I'd love to code some of the basic stuff in R or Perl in scratch. It won't be efficient, but will better help me understand just how actual values are manipulated. I know this isn't the function of the list, but was hoping that someone could point me toward some good resources or offer some suggestion. Thanks, -N
> 1) how calculation of the kernel happens.The kernel is just a "normal function" (though not every function is a proper kernel function): it takes two values (each value being a vector (or something) representing an example) and returns a real valued answer.> 2) how to calculate the predicted value (y_hat) given a list of support > vectors and coefficients.Sum over all S support vectors (SV): coef_s * label_s * kernel_function(SV_s, example) Then add the bias term to that value> I've seen all the formulas and many of the books. ?I get most of it > conceptually. ?Where I'm having trouble is making the leap from concept > to actual use. ?Ideally, I'd love to code some of the basic stuff in R > or Perl in scratch. ?It won't be efficient, but will better help me > understand just how actual values are manipulated. > I know this isn't the function of the list, but was hoping that someone > could point me toward some good resources or offer some suggestion.Go watch Andrew Ng's Machine Learning lectures (they are free online). I think even one of his homework problems was to implement a "simple" SVM solver (though I could be mistaken) -- Steve Lianoglou Graduate Student: Computational Systems Biology | Memorial Sloan-Kettering Cancer Center | Weill Medical College of Cornell University Contact Info: http://cbio.mskcc.org/~lianos/contact