Default value of nominal attributes

Schalkekid

Hi there,
as I am working with nominal attributes very often, I found out that the default value of nominal attributes (also polynominal and binominal ones) is set to 0.0d in the AbstractAttribute-class.
If you are using the default-value-check in the Tools-class a nominal attribute containing the value mapped on first position in the nominal mapping will be marked as containing a default value. This might lead to the ban of the attribute in special cases (for instance in the creation of SVMExamples).
I don't think that this is a problem in everyday work but perhaps it's remarkable for some users.
Unfortunately, I don't have a really good idea how to overcome that problem!

I wrote an SVM-kernel for processing nominal values, and I had to manually check for nominal attributes to be put into the attribute map in any case, also if they are containing "default values".

Best,
Felix

land

Hi,
actually this default value is needed for sparse attributes. Otherwise they won't work. I don't think we can change that anyway in the current data core. But you might add a feature request for that. We then can take this into account when designing the new column based core.

Greetings,
Sebastian