[Scikit-learn-general] Sum of kernels in SVM

2014-11-17 Thread James McMurray
Hi, Is it possible to combine kernels in the SVM in Scikit-learn, i.e. if I wanted a sum of different kernels, or different kernels on different dimensions, etc.? Or would I need to define a new kernel? Best, James McMurray

Re: [Scikit-learn-general] Sum of kernels in SVM

2014-11-17 Thread Michael Eickenberg
Hi James, if by chance your combination of kernels yields one of the built-in kernels for SVM ('linear', 'poly', 'rbf', 'sigmoid', see https://github.com/scikit-learn/scikit-learn/blob/master/sklearn/svm/classes.py#L221), then yes ... :) Otherwise you will have to pass a new kernel function /

Re: [Scikit-learn-general] Sum of kernels in SVM

2014-11-17 Thread James McMurray
Okay, I think the precomputed kernel is the easiest way to do this then. However, I would note that the GPy Gaussian Processes package: https://github.com/SheffieldML/GPy/ Has a built-in way of summing and multiplying the built-in kernels (since these will always yield valid kernels). This could

Re: [Scikit-learn-general] Sum of kernels in SVM

2014-11-17 Thread Andy
Hi James. One issue here is that these are pure python, which is a bit problematic when using machine learning with SVMs. Using a python kernel function means that the whole kernel needs to be precomputed, which can be very time-consuming or might not be feasible because of memory constraints.