Features

• Adds the contrib module for contributed, non-core functionality.
• Adds contrib.scikit_learn_model_converter, which facilitates converting Scikit-Learn tree-based models into TF-DF models.
• Discard hessian splits with score lower than the parents. This change has little effect on the model quality, but it can reduce its size.
• Add internal flag hessian_split_score_subtract_parent to subtract the parent score in the computation of an hessian split score.
• Add support for hyper-parameter optimizers (also called tuner).
• Add text pretty print of trees with tree.pretty() or str(tree).
• Add support for loading YDF models with file prefixes. Newly created models have a random prefix attached to them. This allows combining multiple models in Keras.
• Add support for discretized numerical features.