weka.core.UnassignedDatasetException when creating an unlabeled instance

Question

I trained an IBK classifier with some training data that I created manually as following:

ArrayList atts = new ArrayList();         


        

Answer 1

You will see this error, when you classify a new instance which is not associated with a dataset. You have to associate every new instance you create to an Instances object using setDataset.

//Make a place holder Instances
//If you already have access to one, you can skip this step
Instances dataset = new Instances("testdata", attr, 1);
dataset.setClassIndex(classIdx);

DenseInstance newInst = new DenseInstance(1.0,values);

//To associate your instance with Instances object, in this case dataset
newInst.setDataset(dataset); 

After this you can classify newly created instance.

double classif = ibk.classifyInstance(newInst);

http://www.cs.tufts.edu/~ablumer/weka/doc/weka.core.Instance.html

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