Applying a costmatrix in the Experimenter
by Kamphuis, C. (Claudia)
My problem is the following. I would like to use the WEKA Experimenter
to analyse my dataset, which is highly unbalanced.
In order to overcome this imbalance I want to apply a costmatrix, where
costs of a FP prediction are higher then costs of a FN prediction.
However, when selecting in the Experimenter the following:
Result Generator = CrossValidation Result Producer --> Split Evaluator =
CostSensitiveClassifierSplitEvaluator --> Classifier =
You get to the final window where you can program the base classifier
(J48 in my case) and you can define a costmatrix. By default is mentions
a 1x1 cost matrix.
As my output has two classes I change the costmatrix in a 2x2
contingency table and change the appropriate cost values. The costmatrix
source then automatically changes into Use Explicit cost matrix. After
setting this experiment (with this costmatrix) I run the experiment with
a dataset called: fold0TR.arff
The experiment however is stopped due to an error being: On-demand cost
file doesn't exist: C:\Program Files\Weka-3-4\fold0TR.cost
Does anybody know why I get this error warning, and how I can prevent it
Thanks in advance!
Let op: mijn email adres is vanaf nu C.Kamphuis(a)uu.nl