Re: MISMO Classifier: cannot evaluate Model

> I've been using the MISMO classifier with multi instance data and while
> I can create the classifier (after putting "test=false" in
> $HOME/wekafiles/props/Capabilities.props), I am getting the following
> error message, when I evaluate the created model:
>
> java.lang.IllegalStateException: All class values in a bag must be the
> same! New value: ?
>         at
> weka.filters.unsupervised.attribute.PropositionalToMultiInstance.batchFinished(PropositionalToMultiInstance.java:575)
>         at weka.filters.Filter.useFilter(Filter.java:708)
>         at weka.classifiers.mi.MISMO.distributionForInstance(MISMO.java:1375)
>         at
> weka.classifiers.evaluation.Evaluation.evaluationForSingleInstance(Evaluation.java:2208)
>         at
> weka.classifiers.evaluation.Evaluation.evaluateModelOnceAndRecordPrediction(Evaluation.java:2246)
>         at
> weka.classifiers.evaluation.Evaluation.evaluateModel(Evaluation.java:2122)
>         at weka.classifiers.Evaluation.evaluateModel(Evaluation.java:689)
>
> I have checked my data and created a minimal example of it, but it
> appears that the class value is correct: in my case it's either true or
> false and appears at the end of each ARFF file line. I don't really
> understand what the error message even means. A bag consists of:
>
> bagId,'value1,value2\nvalue3,value4',true
>
> So how could there be different class values in a bag? It's always the
> third argument on the line and can only appear once.

Can you confirm that train and test set are compatible? You can use
the "Instances.equalHeadersMsg" method for that:
https://weka.sourceforge.io/doc.dev/weka/core/Instances.html#equalHeadersMsg-weka.core.Instances-

Cheers, Peter
-- 
Peter Reutemann
Dept. of Computer Science
University of Waikato, Hamilton, NZ
Mobile +64 22 190 2375
https://www.cs.waikato.ac.nz/~fracpete/
http://www.data-mining.co.nz/
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