I want to apply a decision tree learning algorithm to a dataset I have imported from a CSV. The problem is that the "tra" input of the Decision Tree block is still red, stating "Input example set must have special attribute 'label'.". How do I add that label? What is it? I have been playing around with it for some time without results. Any help appreciated.
ADDENDUM: the column's titles have been correctly inferred, so I have no clue on what the 'label' is.