/*
 *  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 com.rapidminer.example.Attribute;
import com.rapidminer.example.Example;
import com.rapidminer.example.ExampleSet;
import com.rapidminer.example.set.SplittedExampleSet;
import com.rapidminer.tools.Tools;

/**
 * Calculates frequencies and weights.
 * 
 * @author Sebastian Land, Ingo Mierswa
 */
public class FrequencyCalculator {

    public FrequencyCalculator() {}
    
    public double[][] getNumericalWeightCounts(ExampleSet exampleSet, Attribute attribute, double splitValue) {
    	Attribute label = exampleSet.getAttributes().getLabel();
    	int numberOfLabels = label.getMapping().size();
    	
    	Attribute weightAttribute = exampleSet.getAttributes().getWeight();
    	
    	double[][] weightCounts = new double[2][numberOfLabels];
    	
    	for (Example example : exampleSet) {
    		int labelIndex = (int)example.getValue(label);
    		double value = example.getValue(attribute);
    		
    		double weight = 1.0d;
    		if (weightAttribute != null)
    			weight = example.getValue(weightAttribute);
    		
    		if (Tools.isLessEqual(value, splitValue)) {
    			weightCounts[0][labelIndex] += weight;	
    		} else {
    			weightCounts[1][labelIndex] += weight;
    		}    		
    	}
    	
    	return weightCounts;
    }
    
    public double[][] getNominalWeightCounts(ExampleSet exampleSet, Attribute attribute) {
    	Attribute label = exampleSet.getAttributes().getLabel();
    	int numberOfLabels = label.getMapping().size();
    	int numberOfValues = attribute.getMapping().size();
    	
    	Attribute weightAttribute = exampleSet.getAttributes().getWeight();
    	
    	double[][] weightCounts = new double[numberOfValues][numberOfLabels];
    	
    	for (Example example : exampleSet) {
    		int labelIndex = (int)example.getValue(label);
    		double value = example.getValue(attribute);
    		if (!Double.isNaN(value)) {
	    		int valueIndex = (int)value;
	    		double weight = 1.0d;
	    		if (weightAttribute != null)
	    			weight = example.getValue(weightAttribute);
	    		weightCounts[valueIndex][labelIndex] += weight;
    		}
    	}
    	
    	return weightCounts;
    }
    
    /** Returns an array of the size of the partitions. 
     *  Each entry contains the sum of all weights of the 
     *  corresponding partition. */
    public double[] getPartitionWeights(SplittedExampleSet splitted) {
        Attribute weightAttribute = splitted.getAttributes().getWeight();
        double[] weights = new double[splitted.getNumberOfSubsets()];
        for (int i = 0; i < splitted.getNumberOfSubsets(); i++) {
            splitted.selectSingleSubset(i);
            for (Example e : splitted) {
                double weight = 1.0d;
                if (weightAttribute != null) {
                    weight = e.getValue(weightAttribute);
                }
                weights[i] += weight;
            }
        }
        return weights;
    }
    
    /** Returns an array of size of the number of different label
     *  values. Each entry corresponds to the weight sum of all
     *  examples with the current label. */
    public double[] getLabelWeights(ExampleSet exampleSet) {
        Attribute label = exampleSet.getAttributes().getLabel();
        Attribute weightAttribute = exampleSet.getAttributes().getWeight();
        double[] weights = new double[label.getMapping().size()];
        for (Example e : exampleSet) {
            int labelIndex = (int)e.getValue(label);
            double weight = 1.0d;
            if (weightAttribute != null) {
                weight = e.getValue(weightAttribute);
            }
            weights[labelIndex] += weight;
        }
        return weights;
    }
    
    /** Returns the sum of the given weights. */
    public double getTotalWeight(double[] weights) {
        double sum = 0.0d;
        for (double w : weights)
            sum += w;
        return sum;
    }
}