/**
* Copyright (c) 2011, SOCIETIES Consortium (WATERFORD INSTITUTE OF TECHNOLOGY (TSSG), HERIOT-WATT UNIVERSITY (HWU), SOLUTA.NET
* (SN), GERMAN AEROSPACE CENTRE (Deutsches Zentrum fuer Luft- und Raumfahrt e.V.) (DLR), Zavod za varnostne tehnologije
* informacijske družbe in elektronsko poslovanje (SETCCE), INSTITUTE OF COMMUNICATION AND COMPUTER SYSTEMS (ICCS), LAKE
* COMMUNICATIONS (LAKE), INTEL PERFORMANCE LEARNING SOLUTIONS LTD (INTEL), PORTUGAL TELECOM INOVAÇÃO, SA (PTIN), IBM Corp.,
* INSTITUT TELECOM (ITSUD), AMITEC DIACHYTI EFYIA PLIROFORIKI KAI EPIKINONIES ETERIA PERIORISMENIS EFTHINIS (AMITEC), TELECOM
* ITALIA S.p.a.(TI), TRIALOG (TRIALOG), Stiftelsen SINTEF (SINTEF), NEC EUROPE LTD (NEC))
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following
* conditions are met:
*
* 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following
* disclaimer in the documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
* BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
* SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
package org.societies.privacytrust.trust.api.util;
import static org.apache.commons.math.util.MathUtils.EPSILON;
import java.util.Arrays;
import org.apache.commons.math.linear.ArrayRealVector;
import org.apache.commons.math.linear.RealVector;
import org.apache.commons.math.stat.StatUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* Describe your class here...
*
* @author <a href="mailto:nicolas.liampotis@cn.ntua.gr">Nicolas Liampotis</a> (ICCS)
* @since 0.3
*/
public class MathUtils {
/** The logging facility. */
private static final Logger LOG = LoggerFactory.getLogger(MathUtils.class);
public static double[] normalise(final double[] sample) {
LOG.debug("normalise: sample={}", Arrays.toString(sample));
final double[] normalisedSample = StatUtils.normalize(sample);
for (int i = 0; i < normalisedSample.length; ++i)
if (Double.isNaN(normalisedSample[i]))
normalisedSample[i] = 0.0d;
LOG.debug("normalise: normalisedSample={}", Arrays.toString(normalisedSample));
return normalisedSample;
}
public static double[] stanine(final double[] input) {
LOG.debug("stanine: input={}", Arrays.toString(input));
final double[] zscores = normalise(input);
final double[] stanines = new double[zscores.length];
for (int i = 0; i < zscores.length; ++i) {
if (zscores[i] < -1.75d)
stanines[i] = 1;
else if (zscores[i] >= -1.75d && zscores[i] < -1.25d)
stanines[i] = 2;
else if (zscores[i] >= -1.25d && zscores[i] < -0.75d)
stanines[i] = 3;
else if (zscores[i] >= -0.75d && zscores[i] < -0.25d)
stanines[i] = 4;
else if (zscores[i] >= -0.25d && zscores[i] < +0.25d)
stanines[i] = 5;
else if (zscores[i] >= +0.25d && zscores[i] < +0.75d)
stanines[i] = 6;
else if (zscores[i] >= +0.75d && zscores[i] < +1.25d)
stanines[i] = 7;
else if (zscores[i] >= +1.25d && zscores[i] < +1.75d)
stanines[i] = 8;
else // if (zscores[i] >= +1.75d)
stanines[i] = 9;
}
LOG.debug("stanine: stanines={}", Arrays.toString(stanines));
return stanines;
}
public static double min(double[] input) {
return StatUtils.min(input);
}
public static double max(double[] input) {
return StatUtils.max(input);
}
public static double mean(double[] input) {
return StatUtils.mean(input);
}
public static double cos(double[] x, double[] y) {
RealVector x_vec = new ArrayRealVector(x);
RealVector y_vec = new ArrayRealVector(y);
if (x_vec.getDimension() != y_vec.getDimension())
throw new IllegalArgumentException(Arrays.toString(x)
+ ", " + Arrays.toString(y) + ": Vector length mismatch"
+ ": Expected " + x_vec.getDimension() + " but was "
+ y_vec.getDimension());
if (org.apache.commons.math.util.MathUtils.equals(0.0d, x_vec.getNorm()))
x_vec = new ArrayRealVector(x_vec.getDimension(), EPSILON);
if (org.apache.commons.math.util.MathUtils.equals(0.0d, y_vec.getNorm()))
y_vec = new ArrayRealVector(y_vec.getDimension(), EPSILON);
return x_vec.dotProduct(y_vec) / (x_vec.getNorm() * y_vec.getNorm());
}
}