svm - Box constraint in libsvm package (compare MATLAB fitcsvm and libsvm options) -
these options of libsvm package:
options: -s svm_type : set type of svm (default 0) 0 -- c-svc 1 -- nu-svc 2 -- one-class svm 3 -- epsilon-svr 4 -- nu-svr -t kernel_type : set type of kernel function (default 2) 0 -- linear: u'*v 1 -- polynomial: (gamma*u'*v + coef0)^degree 2 -- radial basis function: exp(-gamma*|u-v|^2) 3 -- sigmoid: tanh(gamma*u'*v + coef0) -d degree : set degree in kernel function (default 3) -g gamma : set gamma in kernel function (default 1/num_features) -r coef0 : set coef0 in kernel function (default 0) -c cost : set parameter c of c-svc, epsilon-svr, , nu-svr (default 1) -n nu : set parameter nu of nu-svc, one-class svm, , nu-svr (default 0.5) -p epsilon : set epsilon in loss function of epsilon-svr (default 0.1) -m cachesize : set cache memory size in mb (default 100) -e epsilon : set tolerance of termination criterion (default 0.001) -h shrinking: whether use shrinking heuristics, 0 or 1 (default 1) -b probability_estimates: whether train svc or svr model probability estimates, 0 or 1 (default 0) -wi weight: set parameter c of class weight*c, c-svc (default 1)
which 1 svm box-constraint? -c
? if not, how can calculate that? i'm converting libsvm code matlab fitcsvm
function. have these options in matlab:
'cost' — misclassification cost square matrix | structure array misclassification cost, specified comma-separated pair consisting of 'cost' , square matrix or structure. if specify: square matrix cost, cost(i,j) cost of classifying point class j if true class (i.e., rows correspond true class , columns correspond predicted class). specify class order corresponding rows , columns of cost, additionally specify classnames name-value pair argument. structure s, must have 2 fields: s.classnames, contains class names variable of same data type y s.classificationcosts, contains cost matrix rows , columns ordered in s.classnames two-class learning, if specify cost matrix, software updates prior probabilities incorporating penalties described in cost matrix. subsequently, cost matrix resets default. more details on relationships , algorithmic behavior of boxconstraint, cost, prior, standardize, , weights, see algorithms. defaults are: one-class learning, cost = 0. two-class learning, cost(i,j) = 1 if ~= j, , cost(i,j) = 0 if = j. example: 'cost',[0,1;2,0] data types: double | single | struct
///
'boxconstraint' — box constraint 1 (default) | positive scalar box constraint, specified comma-separated pair consisting of 'boxconstraint' , positive scalar. one-class learning, software sets box constraint 1. more details on relationships , algorithmic behavior of boxconstraint, cost, prior, standardize, , weights, see algorithms. example: 'boxconstraint',100 data types: double | single
what differences between cost
, boxconstraint
comparing above libsvm package options?
google , found following:
-c
= boxconstraint
-wi
≈ cost
-g
= 1/(kernelscale^2)
if rbf used
Comments
Post a Comment