Java Weka - 无法创建新的输出文件。使用标准输出

Question

我有一个 Java 程序可以将 CSV 文件转换为 Weka 的 ARFF 格式。

它在任何给定会话中首次运行时运行完美，但随后总是失败并显示消息：

Cannot create a new output file. Standard out is used.

程序如下：

import java.io.File;
import weka.core.Instances;
import weka.core.converters.ArffSaver;
import weka.core.converters.CSVLoader;

public class CSV2Arff {
      /**
   * takes 2 arguments:
   * - CSV input file
   * - ARFF output file
     * @param args
     * @throws java.lang.Exception
   */
  public static void main(String[] args) throws Exception {
    if (args.length != 2) {
      System.out.println("\nUsage: CSV2Arff <input.csv> <output.arff>\n");
      System.exit(1);
    }

    // load CSV
    CSVLoader loader = new CSVLoader();
    loader.setSource(new File(args[0]));
    Instances data = loader.getDataSet();

    // save ARFF
    ArffSaver saver = new ArffSaver();
    saver.setInstances(data);
    saver.setFile(new File(args[1]));
    //saver.setDestination(new File(args[1]));
    saver.writeBatch();
  }
}

来自控制台的完整错误：

Oct 31, 2016 3:53:39 PM org.apache.coyote.AbstractProtocol start
INFO: Starting ProtocolHandler ["http-nio-8080"]
Oct 31, 2016 3:53:39 PM org.apache.coyote.AbstractProtocol start
INFO: Starting ProtocolHandler ["ajp-nio-8009"]
Oct 31, 2016 3:53:39 PM org.apache.catalina.startup.Catalina start
INFO: Server startup in 6142 ms
Cannot create a new output file. Standard out is used.

Answer 1

我认为 ArffSaver 不会覆盖该文件。如果要覆盖它，请在设置为目标之前删除文件（如果存在）。如果您想要连接数据，请尝试 writeIncremental

你有：

saver.setFile(new File(args[1]));

我会选择类似的东西：

File f = new File(args[1]);
if(f.exists()) { 
    f.delete();
};
saver.setFile(new File(args[1]);

Answer 2

按照weka mail list, this error is a file issue. Other emails suggest to use Java I/O approch保存arff文件。

This error is coming from the CSVSaver and indicates that it is unable 
to create the directory and/or file that you've specified. More than 
likely it is something to do with permissions on where it is trying to 
write to.

试试下面的代码。

import java.io.FileWriter;
import java.io.BufferedWriter;
import java.io.File;
import weka.core.Instances;
import weka.core.converters.ArffSaver;
import weka.core.converters.CSVLoader;

public class CSV2Arff {
      /**
   * takes 2 arguments:
   * - CSV input file
   * - ARFF output file
     * @param args
     * @throws java.lang.Exception
   */
  public static void main(String[] args) throws Exception {
    if (args.length != 2) {
      System.out.println("\nUsage: CSV2Arff <input.csv> <output.arff>\n");
      System.exit(1);
    }

    // load CSV
    CSVLoader loader = new CSVLoader();
    loader.setSource(new File(args[0]));
    Instances data = loader.getDataSet();
    String fileName = args[1];


    // save ARFF
    BufferedWriter writer = new BufferedWriter(new FileWriter(fileName));
    writer.write(data.toString());
    writer.flush();
    writer.close();

  }
}

Java Weka - 无法创建新的输出文件。使用标准输出

Java Weka - Cannot create a new output file. Standard out is used

java

csv

weka