Extracting the rules from an ODM Decision Tree model

One of the most interesting of important aspects of a Decision Model is that we as a user can get to see what rules the machine learning algorithm has generated for our data.

I’ve give a number of examples in various blog posts over the past few years on how to generate a number of classification models. An example of the workflow is below.

In the Class Build node we get four models being generated. These include a Generalised Linear Model, Support Vector Machine, Naive Bayes and a Decision Tree model.

We can explore the Decision Tree model by right clicking on the Class Build Node, selecting View Models and then the Decision Tree model, which will be labelled with a ‘DT’ in the name.

As we explore the nodes and branches of the Decision Tree we can see the rule that was generated for a node in the lower pane of the applications. So by clicking on each node we get a different rule appearing in this pane

Sometimes there is a need to extract this rules so that they can be presented to a number of different types of users, to explain to them what is going on.

How can we extract the Decision Tree rules?

To do this, you will need to complete the following steps:

• From the Models section of the Component Palette select the Model Details node.
• Click on the Workflow pane and the Model Details node will be created
• Connect the Class Build node to the Model Details node. To do this right click on the Class Build node and select Connect. Then move the mouse to the Model Details node and click. The two nodes should now be connected.
• Edit the Model Details node, uncheck the Auto Settings, select Model Type to be Decision Tree, Output to be Full Tree and all the columns.

• Run the Model Details node. Right click on the node and select run. When complete you you will have the little green box with a tick mark, on the top right hand corner.
• To view the details produced, right click on the Model Details node and select View Data
• The rules for each node will now be displayed. You will need to scroll to the right of this pane to get to the rules and you will need to expand the columns for the rules to see the full details