/*
* Joinery -- Data frames for Java
* Copyright (c) 2014, 2015 IBM Corp.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package joinery.impl;
import joinery.DataFrame.Function;
import org.apache.commons.math3.stat.descriptive.StorelessUnivariateStatistic;
public class Transforms {
public interface CumulativeFunction<I, O>
extends Function<I, O> {
void reset();
}
private static class AbstractCumulativeFunction<V>
implements CumulativeFunction<Number, Number> {
private final StorelessUnivariateStatistic stat;
private final Number initialValue;
protected AbstractCumulativeFunction(final StorelessUnivariateStatistic stat, final Number initialValue) {
this.stat = stat;
this.initialValue = initialValue;
reset();
}
@Override
public Number apply(final Number value) {
stat.increment(value.doubleValue());
return stat.getResult();
}
@Override
public void reset() {
stat.clear();
stat.increment(initialValue.doubleValue());
}
}
public static class CumulativeSum<V>
extends AbstractCumulativeFunction<V> {
public CumulativeSum() {
super(new org.apache.commons.math3.stat.descriptive.summary.Sum(), 0);
}
}
public static class CumulativeProduct<V>
extends AbstractCumulativeFunction<V> {
public CumulativeProduct() {
super(new org.apache.commons.math3.stat.descriptive.summary.Product(), 1);
}
}
public static class CumulativeMin<V>
extends AbstractCumulativeFunction<V> {
public CumulativeMin() {
super(new org.apache.commons.math3.stat.descriptive.rank.Min(), Double.MAX_VALUE);
}
}
public static class CumulativeMax<V>
extends AbstractCumulativeFunction<V> {
public CumulativeMax() {
super(new org.apache.commons.math3.stat.descriptive.rank.Max(), Double.MIN_VALUE);
}
}
}