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Access support vector in LibSVM and Weka
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import weka.classifiers.functions.LibSVM; | |
import weka.core.Instance; | |
import weka.core.Instances; | |
import weka.core.SelectedTag; | |
import libsvm.svm_model; | |
import java.io.BufferedReader; | |
import java.io.FileReader; | |
import java.lang.reflect.Field; | |
public class SVLibSVM { | |
public static void main(String[] args) throws Exception { | |
BufferedReader reader = new BufferedReader(new FileReader("data/diabetes.arff")); | |
Instances data = new Instances(reader); | |
reader.close(); | |
data.setClassIndex(data.numAttributes() - 1); | |
// create Model | |
LibSVM libsvmModel = new LibSVM(); | |
libsvmModel.setKernelType(new SelectedTag(LibSVM.KERNELTYPE_LINEAR, LibSVM.TAGS_KERNELTYPE)); | |
// train classifier | |
libsvmModel.buildClassifier(data); | |
// extract trained model via reflection, type is libsvm.svm_model | |
// see https://github.com/cjlin1/libsvm/blob/master/java/libsvm/svm_model.java | |
svm_model model = getModel(libsvmModel); | |
// get the indices of the support vectors in the training data | |
// Note: this indices start count at 1 insteadof 0 | |
int[] indices = model.sv_indices; | |
for (int i : indices) { | |
// indices start counting by 1 insteadof 0 so instance i-1 | |
Instance supportVector = data.instance(i - 1); | |
System.out.println(i + ": " + supportVector); | |
} | |
} | |
public static svm_model getModel(LibSVM svm) throws IllegalAccessException, NoSuchFieldException { | |
Field modelField = svm.getClass().getDeclaredField("m_Model"); | |
modelField.setAccessible(true); | |
return (svm_model) modelField.get(svm); | |
} | |
} |
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