How to Make Decision Tree

The tutorial shows how to create a simple decision tree in the fastest way. The hierarchy generation tool helps you to make the tree from text definition with the desired layout.

Start Decision Tree Definition Editor

To make a decision tree in the easiest way you should use the Hierarchy Generation tool in Software Ideas Modeler.

You can access the tool from:

  • Ribbon / Project (tab) / Generate Diagram (group) / Hierarchy Diagram (button)
  • File / Project / Generate Diagram / Hierarchy Diagram

Choose Types of Diagrams and Elements

After clicking the Hierarchy Diagram button (or menu item), the Hierarchy Generation dialog will show.

For a standard decision tree, you need just some basic rectangular elements and a directed arrow connector. So we can select the following options in the drop downs on the General tab page:

  • Diagram type: Flowchart Diagram
  • Box: Process
  • Connector: Flow

However, you can choose any other diagram and element types for boxes and connectors, if they better suit your needs.

Definition of decision tree nodes
Definition of decision tree nodes

Define the Decision Tree

The next steps of this tutorial show you how to create a simple yes-no decision tree in no time.

Enter texts of your decision tree into the Definition box below the drop-downs this way:

  • 1. Start with the main question or the main decision topic of your decision tree - enter its text to the first line and press enter
  • 2. Enter the other follow-up questions to indented lines - press Tab and type (or paste) the question, then press Enter and the line will be automatically indented to the same level as the previous one, so you can just type the second question.
  • 3. Repeat step 2 for additional nested questions.
  • 4. Enter the text of the final decisions on the last level lines.

The lines with the questions should end with question marks, the decision lines should describe results using declarative or imperative sentences. The final decision nodes can also contain the name of a result object.

When the decision tree definition is completed, you can continue with the Branches tab - just type Yes and No to separate lines in the 'Labels for branches' edit box. You can also use other terms, e.g. True and False, Correct and Incorrect, etc.

Definition of decision tree options
Definition of decision tree options

Decision Tree Layout

The Advanced tab allows you to adjust the layout of the generated tree. You should change the Connector direction to 'From parent to child'. Other settings can be unchanged unless you want to modify the default tree layout somehow. The default setting will generate a tree with its root on the top and its branches below it. However, you can generate a tree in any direction. You can also adjust the size of the boxes and the offsets between nodes in a level (Sibling offset) and between two levels (Level offset).

When you press the OK button, the decision tree diagram will be generated and added to the active project.

Configuration of decision tree layout
Configuration of decision tree layout

Generated Decision Tree Example

Example of a generated decision tree
Example of a generated decision tree

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