On 5/31/07, Lt. Castillo <email@example.com> wrote:
I have a question about ID3 algorithm (sorry my english). Some documentation I read said that an atribut can't appear more than once in the tree.
Yes, I think this is correct. Because once you select an attribute at a node, you split the instances.
For the split instances, the gain will be zero for the same attribute. This will be true for the entire subtree below the node, so I think you will not have the same attribute appearing more than once in the tree.
But in weka I saw atributes that appear several times in a tree. My question is:
this happen because of weka is not using ID3 algorithm (I'm using J48-similiar to C4.5, I think) or is because of only the most pure form of ID3 don't allow an atribute to appear more than once in a tree?
Weka does have a seperate ID3 implementation in weka.classifiers.trees.