org.lenskit.specs.data.PrefDomainSpec Maven / Gradle / Ivy
/*
* LensKit, an open source recommender systems toolkit.
* Copyright 2010-2014 LensKit Contributors. See CONTRIBUTORS.md.
* Work on LensKit has been funded by the National Science Foundation under
* grants IIS 05-34939, 08-08692, 08-12148, and 10-17697.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU Lesser General Public License as
* published by the Free Software Foundation; either version 2.1 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 General Public License for more
* details.
*
* You should have received a copy of the GNU General Public License along with
* this program; if not, write to the Free Software Foundation, Inc., 51
* Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
package org.lenskit.specs.data;
import org.lenskit.specs.AbstractSpec;
import javax.annotation.Nonnull;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
/**
* Specification for a preference domain.
*/
public class PrefDomainSpec extends AbstractSpec {
private double minimum;
private double maximum;
private double precision;
public double getMinimum() {
return minimum;
}
public void setMinimum(double minimum) {
this.minimum = minimum;
}
public double getMaximum() {
return maximum;
}
public void setMaximum(double maximum) {
this.maximum = maximum;
}
public double getPrecision() {
return precision;
}
public void setPrecision(double precision) {
this.precision = precision;
}
private static Pattern specRE =
Pattern.compile("\\s*\\[\\s*((?:\\d*\\.)?\\d+)\\s*,\\s*((?:\\d*\\.)?\\d+)\\s*\\]\\s*(?:/\\s*((?:\\d*\\.)?\\d+))?\\s*");
/**
* Parse a preference domain from a string specification.
*
* Continuous preference domains are specified as {@code [min, max]}; discrete domains
* as {@code min:max[/prec/}. For example, a 0.5-5.0 half-star rating scale is represented
* as {@code [0.5, 5.0]/0.5}.
*
* @param spec The string specifying the preference domain.
* @return The preference domain represented by {@code spec}.
* @throws IllegalArgumentException if {@code spec} is not a valid domain specification.
*/
@Nonnull
public static PrefDomainSpec fromString(@Nonnull String spec) {
Matcher m = specRE.matcher(spec);
if (!m.matches()) {
throw new IllegalArgumentException("invalid domain specification");
}
double min = Double.parseDouble(m.group(1));
double max = Double.parseDouble(m.group(2));
String precs = m.group(3);
PrefDomainSpec pds = new PrefDomainSpec();
pds.setMinimum(min);
pds.setMaximum(max);
if (precs != null) {
double prec = Double.parseDouble(precs);
pds.setPrecision(prec);
}
return pds;
}
}