我正在尝试创建测试和训练的Instances对象。训练集中有一些属性在测试集中不存在。尽管如此，我在正确的过滤方法上遇到了麻烦。我尝试了两种过滤器。以下是代码以及它们产生的错误。

Instances rawTraining = new Instances(arffFile);Instances rawTesting = new Instances(arffFile);System.out.println("Raw Training Attributes: "+rawTraining.numAttributes());//Raw Training Attributes: 2446System.out.println("Raw Testing Attributes: "+rawTesting.numAttributes());//Raw Testing Attributes: 2381rawTraining.setClassIndex(rawTraining.numAttributes()-1);

数值转名义过滤器

NumericToNominal filter = new NumericToNominal();filter.setAttributeIndicesArray(new int[] {rawTraining.classAttribute().index()});filter.setInputFormat(rawTraining);Instances finalTraining = Filter.useFilter(rawTraining, filter);Instances finalTesting = Filter.useFilter(rawTesting, filter);

产生以下错误：

java.lang.IllegalArgumentException: Src and Dest differ in # of attributes: 2381 != 2446    at weka.core.RelationalLocator.copyRelationalValues(RelationalLocator.java:87)    at weka.filters.Filter.copyValues(Filter.java:371)    at weka.filters.Filter.bufferInput(Filter.java:313)    at weka.filters.SimpleBatchFilter.input(SimpleBatchFilter.java:199)    at weka.filters.Filter.useFilter(Filter.java:680)

标准化过滤器

Standardize filter = new Standardize();filter.setInputFormat(rawTraining);Instances finalTraining = Filter.useFilter(rawTraining, filter);Instances finalTesting = Filter.useFilter(rawTesting, filter);

产生以下错误：

java.lang.IndexOutOfBoundsException: Index: 2381, Size: 2381    at java.util.ArrayList.rangeCheck(ArrayList.java:653)    at java.util.ArrayList.get(ArrayList.java:429)    at weka.core.Instances.attribute(Instances.java:341)    at weka.core.AbstractInstance.attribute(AbstractInstance.java:72)    at weka.filters.unsupervised.attribute.Standardize.convertInstance(Standardize.java:240)    at weka.filters.unsupervised.attribute.Standardize.input(Standardize.java:142)    at weka.filters.Filter.useFilter(Filter.java:680)

如何使这两个Instances对象兼容？

回答：

这里提供的答案将有助于解决您的一些疑虑：Weka中的测试文件是否需要与训练文件相同或更少的特征。

简而言之，您首先需要确保您的训练和测试实例具有相同的属性（您应该能够在任何类属性中插入’?’）。您提供的代码片段看起来不错，所以我建议先处理这个问题，然后看看会发生什么。