/*
 *  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.preprocessing.transformation.aggregation;

import java.util.HashMap;
import java.util.Map.Entry;

import com.rapidminer.example.Attribute;
import com.rapidminer.example.Example;
import com.rapidminer.example.table.DataRow;

/**
 * This is an {@link Aggregator} for the {@link ModeAggregationFunction}.
 * If the mode is not unique, the first value from the nominal mapping will be used.
 * 
 * @author Sebastian Land
 */
public class ModeAggregator implements Aggregator {

    private Attribute sourceAttribute;
    private double[] frequencies;
    private HashMap<Double, Double> frequenciesMap;

    public ModeAggregator(AggregationFunction function) {
        this.sourceAttribute = function.getSourceAttribute();
        if (sourceAttribute.isNominal())
            frequencies = new double[sourceAttribute.getMapping().size()];
        else
            frequenciesMap = new HashMap<Double, Double>();
    }

    @Override
    public void count(Example example) {
        double value = example.getValue(sourceAttribute);
        if (!Double.isNaN(value)) {
            if (frequencies != null) {
                frequencies[(int) value]++;
            } else {
                Double frequency = frequenciesMap.get(value);
                if (frequency == null)
                    frequenciesMap.put(value, 1d);
                else
                    frequenciesMap.put(value, frequency + 1d);
            }
        }
    }

    @Override
    public void count(Example example, double weight) {
        double value = example.getValue(sourceAttribute);
        if (!Double.isNaN(value))
            if (frequencies != null) {
                frequencies[(int) value] += weight;
            } else {
                Double frequency = frequenciesMap.get(value);
                if (frequency == null)
                    frequenciesMap.put(value, weight);
                else
                    frequenciesMap.put(value, frequency + weight);
            }
    }

    @Override
    public void set(Attribute attribute, DataRow row) {
        double minValue = -1;
        double minFrequency = Double.NEGATIVE_INFINITY;

        if (frequencies != null) {
            for (int i = 0; i < frequencies.length; i++) {
                if (frequencies[i] > minFrequency) {
                    minValue = i;
                    minFrequency = frequencies[i];
                }
            }
        } else {
            for (Entry<Double, Double> entry: frequenciesMap.entrySet()) {
                double frequency = entry.getValue();
                if (frequency > minFrequency) {
                    minValue = entry.getKey();
                    minFrequency = frequency;
                }

            }
        }
        // if any counter was greater 0, set result to maximum
        if (minValue > -1)
            row.set(attribute, minValue);
        else
            row.set(attribute, Double.NaN);
    }
}