In my previous blog post I showed you how you can have a look at the transformations that the Automatic Data Preparation (ADP) feature of Oracle Data Mining produces. I also gave some example of the different types of ADF that are performed for different algorithms.
One of the features of the transformations produced is that it will generate a REVERSE_EXPRESSION. This will take the scored results and apply the inverse of the transformation that was performed when the data was being prepared for input to the algorithm.
Somethings you may want to have the scored data returned in a slightly different ways or labeled in a slightly different way.
In this blog post I will show you how to define an alternative REVERSE_EXPRESSION for an attribute.
The function we need to use for this is the ALTER_REVERSE_EXPRESSION procedure that is part of the DBMS_DATA_MINING package.
When we score data for a typical classification problem we typically use 0 (zero) and 1 to be the target variable values. But what if we wanted the output from our classification model to label the scored data slighted differently.
In this case we can use the ALTER_REVERSE_EXPRESSION procedure to define the new values. What if we wanted the zero to be labeled as NO and the 1 as YES. In this case we can use the following.
model_name => ‘CLAS_NB_1_59’,
expression => ‘decode(affinity_card, ”1”, ”YES”, ”NO”)’,
attribute_name => ‘AFFINITY_CARD’);
When we view the transformations for our data mining model we can now see the transformation.
Now when we score our data the predicted target variable will now have our newly defined values.
PREDICTION(CLAS_NB_1_59 USING *) PRED
FETHC FIRST 5 ROWS ONLY;
You can see that this is a very powerful feature and allows use to turn the scored data values is a different way to make them more useful. This is particularly the case as we work towards a more Automatic type of Predictive Analytics.