/**
* Copyright (C) 2001-2017 by RapidMiner and the contributors
*
* Complete list of developers available at our web site:
*
* http://rapidminer.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 com.rapidminer.example.Attribute;
import com.rapidminer.example.Example;
import com.rapidminer.example.table.DataRow;
/**
* This is an {@link Aggregator} for the {@link LeastAggregationFunction}. If the least value is not
* unique, the first value from the nominal mapping will be used.
*
* @author Sebastian Land
*/
public class LeastAggregator implements Aggregator {
private Attribute sourceAttribute;
private double[] frequencies;
public LeastAggregator(AggregationFunction function) {
this.sourceAttribute = function.getSourceAttribute();
frequencies = new double[sourceAttribute.getMapping().size()];
}
@Override
public void count(Example example) {
count(example, 1d);
}
@Override
public void count(Example example, double weight) {
double value = example.getValue(sourceAttribute);
if (!Double.isNaN(value)) {
frequencies[(int) value] += weight;
}
}
@Override
public void set(Attribute attribute, DataRow row) {
int minIndex = -1;
double minFrequency = Double.POSITIVE_INFINITY;
for (int i = 0; i < frequencies.length; i++) {
if (frequencies[i] < minFrequency) {
minIndex = i;
minFrequency = frequencies[i];
}
}
// if any counter was greater 0, set result to maximum
if (minIndex > -1) {
row.set(attribute, attribute.getMapping().mapString(sourceAttribute.getMapping().mapIndex(minIndex)));
} else {
row.set(attribute, Double.NaN);
}
}
}