/*
 *  RapidMiner
 *
 *  Copyright (C) 2001-2011 by Rapid-I and the contributors
 *
 *  Complete list of developers available at our web site:
 *
 *       http://rapid-i.com
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU Affero General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU Affero General Public License for more details.
 *
 *  You should have received a copy of the GNU Affero General Public License
 *  along with this program.  If not, see http://www.gnu.org/licenses/.
 */
package com.rapidminer.operator.learner.tree;

import java.util.LinkedList;
import java.util.List;

import com.rapidminer.example.ExampleSet;
import com.rapidminer.operator.OperatorCapability;
import com.rapidminer.operator.OperatorDescription;
import com.rapidminer.operator.OperatorException;
import com.rapidminer.parameter.ParameterType;

/**
 * This operator learns decision stumps, i.e. a small decision tree with only one single split. This decision stump
 * works on both numerical and nominal attributes.
 * 
 * @author Ingo Mierswa
 */
public class DecisionStumpLearner extends AbstractTreeLearner {

    public DecisionStumpLearner(OperatorDescription description) {
        super(description);
    }

    @Override
    public Pruner getPruner() throws OperatorException {
        return null;
    }

    @Override
    public List<Terminator> getTerminationCriteria(ExampleSet exampleSet) {
        List<Terminator> result = new LinkedList<Terminator>();
        result.add(new SingleLabelTermination());
        result.add(new NoAttributeLeftTermination());
        result.add(new EmptyTermination());
        result.add(new MaxDepthTermination(2));
        return result;
    }

    @Override
    public boolean supportsCapability(OperatorCapability capability) {
        switch (capability) {
        case BINOMINAL_ATTRIBUTES:
        case POLYNOMINAL_ATTRIBUTES:
        case NUMERICAL_ATTRIBUTES:
        case POLYNOMINAL_LABEL:
        case BINOMINAL_LABEL:
        case WEIGHTED_EXAMPLES:
        case MISSING_VALUES:
            return true;
        default:
            return false;
        }
    }

    @Override
    public List<ParameterType> getParameterTypes() {
        List<ParameterType> types = new LinkedList<ParameterType>();
        for (ParameterType type : super.getParameterTypes()) {
            if (type.getKey().equals(PARAMETER_MINIMAL_LEAF_SIZE)) {
                type.setDefaultValue(Integer.valueOf(1));
            }

            if (!type.getKey().equals(PARAMETER_MINIMAL_GAIN) && !type.getKey().equals(PARAMETER_MINIMAL_SIZE_FOR_SPLIT))
                types.add(type);
        }
        return types;
    }

    @Override
    protected TreeBuilder getTreeBuilder(ExampleSet exampleSet) throws OperatorException {
        return new TreeBuilder(createCriterion(0.0), getTerminationCriteria(exampleSet), getPruner(), getSplitPreprocessing(), new DecisionTreeLeafCreator(), true, 0, 0, getParameterAsInt(PARAMETER_MINIMAL_LEAF_SIZE));
    }
}