/*
* Copyright 2004-2010 Information & Software Engineering Group (188/1)
* Institute of Software Technology and Interactive Systems
* Vienna University of Technology, Austria
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.ifs.tuwien.ac.at/dm/somtoolbox/license.html
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package at.tuwien.ifs.somtoolbox.data.normalisation;
import java.io.IOException;
import at.tuwien.ifs.somtoolbox.util.StringUtils;
/**
* Min-max normalisation, normalises the attributes between 0 and 1.
*
* @author Rudolf Mayer
* @version $Id: MinMaxNormaliser.java 3358 2010-02-11 14:35:07Z mayer $
*/
public class MinMaxNormaliser extends AbstractNormaliser {
double[] minValues;
double[] maxValues;
@Override
public void preReading() {
// in min-max data structure
minValues = new double[dim];
maxValues = new double[dim];
for (int i = 0; i < minValues.length; i++) {
minValues[i] = Double.MAX_VALUE;
maxValues[i] = Double.MIN_VALUE;
}
}
@Override
public void postReading() throws IOException {
// normalise and write the data
for (int i = 0; i < data.rows(); i++) {
for (int j = 0; j < data.columns(); j++) {
double v = data.getQuick(i, j);
v = (v - minValues[j]) / (maxValues[j] - minValues[j]);
if (v == 0) {
writer.write("0 ");
} else {
writer.write(StringUtils.format(v, 15) + " ");
}
}
writer.write(dataNames[i]);
writer.newLine();
}
}
@Override
protected void processLine(int index, String[] lineElements) throws Exception {
for (int ve = 0; ve < dim; ve++) {
double value = Double.parseDouble(lineElements[ve]);
setMatrixValue(index, ve, value);
if (value < minValues[ve]) {
minValues[ve] = value;
}
if (value > maxValues[ve]) {
maxValues[ve] = value;
}
}
addInstance(index, lineElements[dim]);
}
}