title: Weka Gridsearch libsvm cannot handle unary class (one-class)
body: <p>I'm trying to obtain the best parameters for a one-class classifer using the wrapper of LibSVM under Weka.</p>
  
  <p>For this reason, I'm going to <strong>weka.classifiers.meta.GridSearch</strong> and then I select <strong>LibSVM one class</strong>.</p>
  
  <p>All data I'm using is labeled as the same class. The parameters I want to find are <strong>nu</strong> and <strong>gamma</strong></p>
  
  <p>The gridSearch options are:</p>
  
  <p>weka.classifiers.meta.GridSearch -E CC -y-property classifier.kernel.gamma -y-min -5.0 -y-max 2.0 -y-step 1.0 -y-base 10.0 -y-expression pow(BASE,I) -filter weka.filters.AllFilter -x-property classifier.nu -x-min 0.01 -x-max 1.0 -x-step 10.0 -x-base 10.0 -x-expression I -sample-size 100.0 -traversal COLUMN-WISE -log-file "C:\Program Files\Weka-3-6" -S 1 -W weka.classifiers.functions.LibSVM -- -S 2 -K 2 -D 3 -G 0.0 -R 0.0 -N 0.5 -M 40.0 -C 1.0 -E 0.0010 -P 0.1</p>
  
  <p>Then, weka tells me this:</p>
  
  <p><em><strong>weka.classifiers.meta.GridSearch Cannot handle unary class!!!</em></strong></p>
  
  <p>Is it true that gridsearch cannot handle unary class? or I'm just doing something wrong?</p>
  
  <p>Thank you for your help.</p>
  
  <p>-Jessica</p>