java - 为什么在Weka中使用libsvm时出现 "NoClassDefFoundError:libsvm/svm_print_interface"错误？

Question

我的任务是在weka中使用libsvm对Iris数据集进行分类。首先，我在weka资源管理器中运行它并得到我的理想结果。

然后我在 eclipse 中编写它，希望得到与下面的 weka explorer 显示相同的结果。这是我的代码(您可以忽略除 main 函数之外的任何代码)。

    package weka;
    import java.io.BufferedReader;
    import java.io.FileReader;
    import java.util.Vector;

    import weka.classifiers.AbstractClassifier;
    import weka.classifiers.Classifier;
    import weka.classifiers.Evaluation;
    import weka.core.Instances;
    import weka.core.OptionHandler;
    import weka.core.Utils;
    import weka.filters.Filter;

    import weka.classifiers.functions.LibSVM;

    public class ClassifyIriswithLibsvm {
     /** the classifier used internally */
      protected Classifier m_Classifier = null;

      /** the filter to use */
      protected Filter m_Filter = null;

      /** the training file */
      protected String m_TrainingFile = null;

      /** the training instances */
      protected Instances m_Training = null;

      /** for evaluating the classifier */
      protected Evaluation m_Evaluation = null;

      /**
       * initializes the demo
       */
      public ClassifyIriswithLibsvm () {
        super();
      }

      /**
       * sets the classifier to use
       * 
       * @param name the classname of the classifier
       * @param options the options for the classifier
       */
      public void setClassifier(String name, String[] options) throws Exception {
        m_Classifier = AbstractClassifier.forName(name, options);
      }

      /**
       * sets the filter to use
       * 
       * @param name the classname of the filter
       */
      public void setFilter(String name) throws Exception {
        m_Filter = (Filter) Class.forName(name).newInstance();
        if (m_Filter instanceof OptionHandler) {
          ((OptionHandler) m_Filter).setOptions(options);
        }
      }

      /**
       * sets the file to use for training
       */
      public void setTraining(String name) throws Exception {
        m_TrainingFile = name;
        m_Training = new Instances(new BufferedReader(
          new FileReader(m_TrainingFile)));
        m_Training.setClassIndex(m_Training.numAttributes() - 1);
      }

      /**
       * runs 10fold CV over the training file
       */
      public void execute() throws Exception {
        // run filter
        m_Filter.setInputFormat(m_Training);
        Instances filtered = Filter.useFilter(m_Training, m_Filter);

        // train classifier on complete file for tree
        m_Classifier.buildClassifier(filtered);

        // 10fold CV with seed=1
        m_Evaluation = new Evaluation(filtered);
        m_Evaluation.crossValidateModel(m_Classifier, filtered, 10,
          m_Training.getRandomNumberGenerator(1));
      }

      /**
       * outputs some data about the classifier
       */
      @Override
      public String toString() {
        StringBuffer result;

        result = new StringBuffer();
        result.append("Weka - Demo\n===========\n\n");

        result.append("Classifier...: " + Utils.toCommandLine(m_Classifier) + "\n");
        if (m_Filter instanceof OptionHandler) {
          result.append("Filter.......: " + m_Filter.getClass().getName() + " "
            + Utils.joinOptions(((OptionHandler) m_Filter).getOptions()) + "\n");
        } else {
          result.append("Filter.......: " + m_Filter.getClass().getName() + "\n");
        }
        result.append("Training file: " + m_TrainingFile + "\n");
        result.append("\n");

        result.append(m_Classifier.toString() + "\n");
        result.append(m_Evaluation.toSummaryString() + "\n");
        try {
          result.append(m_Evaluation.toMatrixString() + "\n");
        } catch (Exception e) {
          e.printStackTrace();
        }
        try {
          result.append(m_Evaluation.toClassDetailsString() + "\n");
        } catch (Exception e) {
          e.printStackTrace();
        }

        return result.toString();
      }

      public static void main(String[] args) throws Exception {


          String classifier = "weka.classifiers.functions.LibSVM" ;
          String options = ( "-S 0 -K 0 -D 3 -G 0.0 -R 0.0 -N 0.5 -M 40.0 -C 1.0 -E 0.001 -P 0.1" );
          String[] classifierOptions = options.split( " " );
          String filter = "weka.filters.unsupervised.instance.Randomize ";

          String dataset = "D:\\SoftWare\\weka3.8.2\\Weka-3-8\\data\\iris.arff";

        // run
        ClassifyIriswithLibsvm demo = new ClassifyIriswithLibsvm();
        demo.setClassifier(classifier,
          classifierOptions);
        demo.setFilter(filter);
        demo.setTraining(dataset);
        demo.execute();
        System.out.println(demo.toString());
      }
}

但是错误打印如下

`Exception in thread "main" java.lang.NoClassDefFoundError: libsvm/svm_print_interface
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Unknown Source)
    at weka.core.WekaPackageClassLoaderManager.forName(WekaPackageClassLoaderManager.java:198)
    at weka.core.WekaPackageClassLoaderManager.forName(WekaPackageClassLoaderManager.java:178)
    at weka.core.WekaPackageClassLoaderManager.objectForName(WekaPackageClassLoaderManager.java:162)
    at weka.Run.findSchemeMatch(Run.java:90)
    at weka.core.ResourceUtils.forName(ResourceUtils.java:76)
    at weka.core.Utils.forName(Utils.java:1045)
    at weka.classifiers.AbstractClassifier.forName(AbstractClassifier.java:91)
    at weka.ClassifyIriswithLibsvm.setClassifier(ClassifyIriswithLibsvm.java:46)
    at weka.ClassifyIriswithLibsvm.main(ClassifyIriswithLibsvm.java:221)
Caused by: java.lang.ClassNotFoundException: libsvm.svm_print_interface
    at java.net.URLClassLoader.findClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    ... 11 more
`

我不明白为什么这是错误的。我是 libsvm 和 weka 的新手。如何在 weka 中使用 libsvm 成功运行 classiyier 程序？

Answer 1

您需要确保 libsvm.jar 在您的类路径(在 Eclipse 中)中可用。

您可以查看this answer在 Stackoverflow 上获取所有必要的依赖项，它们是 libsvm.jar、wlsvm.jar 和(当然)weka.jar。