在 Weka 中创建兼容的训练和测试实例

Question

我正在尝试创建测试和训练 Instances 对象。 train 中有一些属性没有在 test 中。不过，我在使用正确的过滤方法时遇到了麻烦。我试过两个过滤器。下面是包含它们产生的错误的代码。

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

数值到名义滤波器

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)

如何使这两个实例兼容？

Answer 1

此处提供的答案将有助于解决您的一些疑虑：Does test file in WEKA require or less number of features as train。

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 class 属性中插入“？”）。你提供的代码片段看起来不错，所以我会先处理这个然后看看会发生什么。

在 Weka 中创建兼容的训练和测试实例

Creating Compatible Train and Test Instances in Weka

java

machine-learning

weka

arff