Suppose I have a prediction from a model outside WEKA. Is there a way I can
compute the WEKA accuracy metrics of this model? I.e., I should be able to
feed WEKA with the predicted and actual values and apply some sort of no
prediction. The reason would be to easily compare the WEKA predictions to
this external prediction. Yes I could compute the metrics of the external
model by myself but the devil is in the details...
If you have a single test set for which you want performance statistics, you can achieve what you want by using appropriately structured training and test data files together with IBk. An example is given below. The train.arff file has the class values that we want to predict. The test.arff file has the actual class values.
The idea is to use IBk to implement a form of lookup table: the first attribute in the data indicates the value to look up.