how does "nominal2numeric" work?

cantabcantab Member Posts: 6 Contributor II
This question is related to a recent one, but easier, I hope.

The documentation for "nominal2numeric" says 

"For nominal attributes one of the following calculations will be done:

Dichotomization, i.e. one new attribute for each value of the nominal
attribute. The new attribute which corresponds to the actual nominal
value gets value 1 and all other attributes gets value 0.

Alternatively the values of nominal attributes can be seen as equally
ranked, therefore the nominal attribute will simply be turned into a real
valued attribute, the old values results in equidistant real values."

My question is how to get the first behavior, i.e. dichotomization?  The default is the second behavior.  There does not seem to be a parameter for the operator that gives the first behavior.

Answers

  • TobiasMalbrechtTobiasMalbrecht Moderator, Employee, Member Posts: 289  Guru
    Hi,

    unfortunately, this operator description is misleading as it describes the general procedure or options to convert nominal attributes to numerical ones. But as you correctly observed the [tt]Nominal2Numerical[/tt] operator simply converts the nominal values to the internal double (numerical) representation of RM.

    To dichotomize the values, simply use the [tt]Nominal2Binominal[/tt] operator before applying the [tt]Nominal2Numerical[/tt] operator.

    Kind regards,
    Tobias
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