Re: Level Order Tree Traversal of C4.5 (J48) Tree

Here is some code (again, written in the Groovy console) that outputs the
tree in breadth-first order.

Cheers,
Eibe

package weka.classifiers.trees.j48;

import weka.core.Instances;
import weka.classifiers.trees.J48;

class MyJ48 extends J48 {

 public static String breadthFirst(ClassifierTree tree){
  StringBuffer buffer = new StringBuffer();
  Queue<ClassifierTree> fifoQueue = new LinkedList<>();
  fifoQueue.add(tree);
  while (!fifoQueue.isEmpty()) {
   ClassifierTree firstElement = fifoQueue.pop();
   if (!firstElement.isLeaf()) {
    for (int i = 0; i < firstElement.m_sons.length; i++) {
     buffer.append(firstElement.m_localModel.leftSide(firstElement.m_train)
+ firstElement.m_localModel.rightSide(i, firstElement.m_train) + "\n");
     ClassifierTree currentSuccessor = firstElement.m_sons[i];
     fifoQueue.add(currentSuccessor);
    }
   } else {
    buffer.append(": " + firstElement.m_localModel.dumpLabel(0,
firstElement.m_train) + "\n");
   }
  }
  return buffer.toString();
 }

 public static void main(String[] args) {
  Instances data = (new
weka.core.converters.ConverterUtils.DataSource("C:/Users/eibe/datasets/UCI/anneal.arff")).getDataSet();
  data.setClassIndex(data.numAttributes() - 1);
  J48 j48 = new J48();
  j48.buildClassifier(data);
  System.out.println(j48);
  System.out.println("Breadth-first traversal: \n\n" +
MyJ48.breadthFirst(j48.m_root));
 }
}

On Tue, Jun 29, 2021 at 8:56 PM <[email protected]> wrote:

> I include the code together with some changes. First the method:
>
> private void dumpTreeLevelOrder(Instances root, StringBuffer text){
>
>     if (root==null)
>       return;
>
>     Queue<Instances> q =new LinkedList<>();
>     q.add(root);
>     int height=1;
>     while(!q.isEmpty()){
>       for (int k=0; k<height; k++)
>         text.append("|  ");
>       int n = q.size();
>       while (n>0){
>         Instances p = q.peek();
>         q.remove();
>         text.append(m_localModel.leftSide(p));
>         text.append(m_localModel.rightSide(1, p)+" ");
>         for (int i=0; i<m_sons.length; i++)
>           q.add(m_sons[i].m_train);
>         n--;
>       }
>       height++;
>       text.append("\n");
>     }
>
>   }
>
> And next the call from the toString() method:
>
> dumpTreeLevelOrder(m_train, text);
>
> Any help would be valuable!
>
> Thank you in advance,
>
> Spyros Halkidis
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