在Android中使用Weka将CSV转换为ARFF时出错 [英] Errors when converting CSV to ARFF in Android using Weka
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问题描述
我正在演唱在weka网站上找到的代码和说明 https://weka .wikispaces.com/Converting + CSV + to + ARFF
但是由于某种原因，它给了我错误.注意，我检查以确保文件存在并且可读.
CSVLoader.java的代码
https://github.com/rjmarsan/Weka-for-Android/blob/925a77b566d6e55a775911fbf317234d11ec8024/src/weka/core/converters/CSVLoader.java
Android代码
String input = Environment.getExternalStorageDirectory().getAbsolutePath()+"/homework1/user_patterns.csv";
String output = Environment.getExternalStorageDirectory().getAbsolutePath()+"/homework1/user_patterns.arff";
Instances data = null;
try {
File inputFile = new File(input);
System.out.println(inputFile.exists());
System.out.println(inputFile.canRead());
// load CSV
CSVLoader loader = new CSVLoader();
loader.setSource(inputFile);
data = loader.getDataSet();
// save ARFF
ArffSaver saver = new ArffSaver();
saver.setInstances(data);
saver.setFile(new File(output));
saver.writeBatch();
} catch (IOException err) {
System.out.println(err);
}
堆栈跟踪
09-30 15:23:03.810 22869-22869/com.weka W/dalvikvm﹕ Exception Ljava/lang/NullPointerException; thrown while initializing Lweka/core/converters/ConverterUtils;
09-30 15:23:03.810 22869-22869/com.weka W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0xa4d12b20)
09-30 15:23:03.814 22869-22869/com.weka E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.weka, PID: 22869
java.lang.ExceptionInInitializerError
at weka.core.converters.CSVLoader.readHeader(CSVLoader.java:882)
at weka.core.converters.CSVLoader.readStructure(CSVLoader.java:534)
at weka.core.converters.CSVLoader.getStructure(CSVLoader.java:519)
at weka.core.converters.CSVLoader.getDataSet(CSVLoader.java:552)
at com.weka.MainMenu$1.onClick(MainMenu.java:105)
at android.view.View.performClick(View.java:4438)
at android.view.View$PerformClick.run(View.java:18422)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5001)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at weka.core.converters.ConverterUtils.<clinit>(ConverterUtils.java:741)
at weka.core.converters.CSVLoader.readHeader(CSVLoader.java:882)
at weka.core.converters.CSVLoader.readStructure(CSVLoader.java:534)
at weka.core.converters.CSVLoader.getStructure(CSVLoader.java:519)
at weka.core.converters.CSVLoader.getDataSet(CSVLoader.java:552)
at com.weka.MainMenu$1.onClick(MainMenu.java:105)
at android.view.View.performClick(View.java:4438)
at android.view.View$PerformClick.run(View.java:18422)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5001)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
at dalvik.system.NativeStart.main(Native Method)
请注意，MainMenu.java:105引用了data = loader.getDataSet();
解决方案
您链接的源代码仅在 weka.core.converters.ConverterUtils.java 行741中包含注释，因此猜测您实际使用的是 https ://www.pervasive.jku.at/Teaching/lvaInfo.php?key = 346& do = uebungen
问题在于，在静态类初始化程序中，几乎所有内容都被注释掉了，仅留下第741行会失败，因为调用m_FileLoaders.size()时静态字段m_FileLoaders仍为null:
/** all available loaders (extension <-> classname). */
protected static Hashtable<String,String> m_FileLoaders;
[...]
// determine all loaders/savers
static {
Vector classnames;
try {
// generate properties
// Note: does NOT work with RMI, hence m_FileLoadersCore/m_FileSaversCore
/* GenericPropertiesCreator creator = new GenericPropertiesCreator();
creator.execute(false);
Properties props = creator.getOutputProperties();
// init
m_FileLoaders = new Hashtable<String,String>();
[...]
*/
}
catch (Exception e) {
// ignore
}
finally {
// loaders
if (m_FileLoaders.size() == 0) {
/*classnames = GenericObjectEditor.getClassnames(AbstractFileLoader.class.getName());
[...]
*/
}
}
}
总而言之，我最好的猜测是罐子是破损的，所以您可以自己修理它，或者得到一个不破损的瓶子.
(顺便说一句:另一个具有相同问题的问题.)
I'm sing the code and instructions found on the weka site https://weka.wikispaces.com/Converting+CSV+to+ARFF
But for some reason its giving me errors. Notice I check to make sure the file exists and is readable.
Code for CSVLoader.java
https://github.com/rjmarsan/Weka-for-Android/blob/925a77b566d6e55a775911fbf317234d11ec8024/src/weka/core/converters/CSVLoader.java
Android Code
String input = Environment.getExternalStorageDirectory().getAbsolutePath()+"/homework1/user_patterns.csv";
String output = Environment.getExternalStorageDirectory().getAbsolutePath()+"/homework1/user_patterns.arff";
Instances data = null;
try {
File inputFile = new File(input);
System.out.println(inputFile.exists());
System.out.println(inputFile.canRead());
// load CSV
CSVLoader loader = new CSVLoader();
loader.setSource(inputFile);
data = loader.getDataSet();
// save ARFF
ArffSaver saver = new ArffSaver();
saver.setInstances(data);
saver.setFile(new File(output));
saver.writeBatch();
} catch (IOException err) {
System.out.println(err);
}
Stack Trace
09-30 15:23:03.810 22869-22869/com.weka W/dalvikvm﹕ Exception Ljava/lang/NullPointerException; thrown while initializing Lweka/core/converters/ConverterUtils;
09-30 15:23:03.810 22869-22869/com.weka W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0xa4d12b20)
09-30 15:23:03.814 22869-22869/com.weka E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.weka, PID: 22869
java.lang.ExceptionInInitializerError
at weka.core.converters.CSVLoader.readHeader(CSVLoader.java:882)
at weka.core.converters.CSVLoader.readStructure(CSVLoader.java:534)
at weka.core.converters.CSVLoader.getStructure(CSVLoader.java:519)
at weka.core.converters.CSVLoader.getDataSet(CSVLoader.java:552)
at com.weka.MainMenu$1.onClick(MainMenu.java:105)
at android.view.View.performClick(View.java:4438)
at android.view.View$PerformClick.run(View.java:18422)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5001)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at weka.core.converters.ConverterUtils.<clinit>(ConverterUtils.java:741)
at weka.core.converters.CSVLoader.readHeader(CSVLoader.java:882)
at weka.core.converters.CSVLoader.readStructure(CSVLoader.java:534)
at weka.core.converters.CSVLoader.getStructure(CSVLoader.java:519)
at weka.core.converters.CSVLoader.getDataSet(CSVLoader.java:552)
at com.weka.MainMenu$1.onClick(MainMenu.java:105)
at android.view.View.performClick(View.java:4438)
at android.view.View$PerformClick.run(View.java:18422)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5001)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
at dalvik.system.NativeStart.main(Native Method)
Note that MainMenu.java:105 refers to data = loader.getDataSet();
解决方案
The source code you linked only contains a comment in weka.core.converters.ConverterUtils.java line 741, so I'm guessing that what you are actually using is the jar from here: https://www.pervasive.jku.at/Teaching/lvaInfo.php?key=346&do=uebungen
The problem there is that in the static class initializer, almost everything is commented out, leaving only line 741 that will fail because the static field m_FileLoaders is still null when m_FileLoaders.size() is called:
/** all available loaders (extension <-> classname). */
protected static Hashtable<String,String> m_FileLoaders;
[...]
// determine all loaders/savers
static {
Vector classnames;
try {
// generate properties
// Note: does NOT work with RMI, hence m_FileLoadersCore/m_FileSaversCore
/* GenericPropertiesCreator creator = new GenericPropertiesCreator();
creator.execute(false);
Properties props = creator.getOutputProperties();
// init
m_FileLoaders = new Hashtable<String,String>();
[...]
*/
}
catch (Exception e) {
// ignore
}
finally {
// loaders
if (m_FileLoaders.size() == 0) {
/*classnames = GenericObjectEditor.getClassnames(AbstractFileLoader.class.getName());
[...]
*/
}
}
}
All in all, my best guess is that the jar is broken, so either you fix it yourself or get a non-broken one.
(Btw: Another question with the same problem.)
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