java - Test a single instance in Weka

Question

Does weka require the test instances to have the class attribute. I have used a training set arff file to train the classifier. Now I want to test an instance (not from arff file, have to create by code) without the class attribute and predict the class. I found this link Weka: How do I get the prediction value in java for a test instance?

But my class attribute is a string 'Y' or 'N'. If evaluateModelOnce() returns double, what does it mean. Is it the class attribute or something else. i am using the weka API.

Answer 1

要测试实例，实例必须具有类标签。即使您提供类标签，在使用构建的模型进行分类时，Weka 也看不到测试实例的类标签。而是在测试之后，它匹配它对测试实例类的预测是否正确。如果您在训练实例中有标签（您必须有）而不是在测试实例上，那么您将收到一条错误消息，例如“训练集和测试集不兼容”。谢谢你。