weka.core.UnassignedClassException：类索引为负（未设置）！

Question

我尝试对一个csv文件实施线性回归。这是csv文件的内容：

X1; X2; X3; X4; X5; X6; X7; X8; Y1; Y2;

0.98; 514.50; 294.00; 110.25; 7.00; 2; 0.00; 0; 15.55; 21.33; 0.98; 514.50; 294.00; 110.25; 7.00; 3; 0.00; 0; 15.55; 21.33; 0.98; 514.50; 294.00; 110.25; 7.00; 4; 0.00; 0; 15.55; 21.33; 0.98; 514.50; 294.00; 110.25; 7.00; 5; 0.00; 0; 15.55; 21.33; 0.90; 563.50; 318.50; 122.50; 7.00; 2; 0.00; 0; 20.84; 28.28; 0.90; 563.50; 318.50; 122.50; 7.00; 3; 0.00; 0; 21.46; 25.38; 0.90; 563.50; 318.50; 122.50; 7.00; 4; 0.00; 0; 20.71; 25.16; 0.90; 563.50; 318.50; 122.50; 7.00; 5; 0.00; 0; 19.68; 29.60; 0.86; 588.00; 294.00; 147.00; 7.00; 2; 0.00; 0; 19.50; 27.30; 0.86; 588.00; 294.00; 147.00; 7.00; 3; 0.00; 0; 19.95; 21.97; 0.86; 588.00; 294.00; 147.00; 7.00; 4; 0.00; 0; 19.34; 23.49; 0.86; 588.00; 294.00; 147.00; 7.00; 5; 0.00; 0; 18.31; 27.87; 0.82; 612.50; 318.50; 147.00; 7.00; 2; 0.00; 0; 17.05; 23.77;

...

0.71; 710.50; 269.50; 220.50; 3.50; 2; 0.40; 5; 12.43; 15.59; 0.71; 710.50; 269.50; 220.50; 3.50; 3; 0.40; 5; 12.63; 14.58; 0.71; 710.50; 269.50; 220.50; 3.50; 4; 0.40; 5; 12.76; 15.33; 0.71; 710.50; 269.50; 220.50; 3.50; 5; 0.40; 5; 12.42; 15.31; 0.69; 735.00; 294.00; 220.50; 3.50; 2; 0.40; 5; 14.12; 16.63; 0.69; 735.00; 294.00; 220.50; 3.50; 3; 0.40; 5; 14.28; 15.87; 0.69; 735.00; 294.00; 220.50; 3.50; 4; 0.40; 5; 14.37; 16.54; 0.69; 735.00; 294.00; 220.50; 3.50; 5; 0.40; 5; 14.21; 16.74; 0.66; 759.50; 318.50; 220.50; 3.50; 2; 0.40; 5; 14.96; 17.64; 0.66; 759.50; 318.50; 220.50; 3.50; 3; 0.40; 5; 14.92; 17.79; 0.66; 759.50; 318.50; 220.50; 3.50; 4; 0.40; 5; 14.92; 17.55; 0.66; 759.50; 318.50; 220.50; 3.50; 5; 0.40; 5; 15.16; 18.06; 0.64; 784.00; 343.00; 220.50; 3.50; 2; 0.40; 5; 17.69; 20.82; 0.64; 784.00; 343.00; 220.50; 3.50; 3; 0.40; 5; 18.19; 20.21; 0.64; 784.00; 343.00; 220.50; 3.50; 4; 0.40; 5; 18.16; 20.71; 0.64; 784.00; 343.00; 220.50; 3.50; 5; 0。40; 5; 17.88; 21.40; 0.62; 808.50; 367.50; 220.50; 3.50; 2; 0.40; 5; 16.54; 16.88; 0.62; 808.50; 367.50; 220.50; 3.50; 3; 0.40; 5; 16.44; 17.11; 0.62; 808.50; 367.50; 220.50; 3.50; 4; 0.40; 5; 16.48; 16.61; 0.62; 808.50; 367.50; 220.50; 3.50; 5; 0.40; 5; 16.64; 16.03;

我阅读了此csv文件并实现了线性回归实现。这是java中的源代码：

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


         String csvFile = null;       
         CSVLoader loader = null;         
         Remove remove =null;        
         Instances data =null;        
         LinearRegression model = null;
         int numberofFeatures = 0;

         try 
         {

             csvFile = "C:\\Users\\Taha\\Desktop/ENB2012_data.csv";         
             loader = new CSVLoader();


             // load CSV      
             loader.setSource(new File(csvFile));   
             data = loader.getDataSet();
             //System.out.println(data);
             numberofFeatures = data.numAttributes();

             System.out.println("number of features: " + numberofFeatures);

             data.setClassIndex(data.numAttributes() - 2);

             //remove last attribute Y2
             remove = new Remove();         
             remove.setOptions(new String[]{"-R", data.numAttributes()+""});
             remove.setInputFormat(data);  

             data = Filter.useFilter(data, remove);

            // data.setClassIndex(data.numAttributes() - 2);

             model = new LinearRegression();
             model.buildClassifier(data); 
             System.out.println(model);

         } catch (Exception e) { 
                // TODO Auto-generated catch block
                e.printStackTrace();
         }

我遇到错误weka.core.UnassignedClassException：类索引为负（未设置）！在model.buildClassifier（data）;行 功能数量为1，但是预计为9。它们是X1; X2; X3; X4; X5; X6; X7; X8; Y1; Y2我缺少什么？提前致谢。

Answer 1

您可以在该行之后添加data=loader.getDataSet()下一行，以解决您的异常：

if (data.classIndex() == -1) {
        System.out.println("reset index...");
        instances.setClassIndex(data.numAttributes() - 1);
    }

这对我有用。