/**
* diqube: Distributed Query Base.
*
* Copyright (C) 2015 Bastian Gloeckle
*
* This file is part of diqube.
*
* diqube 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 org.diqube.function.aggregate;
import java.util.HashMap;
import java.util.Map;
import java.util.OptionalDouble;
import java.util.PriorityQueue;
import java.util.stream.Stream;
import org.diqube.data.column.ColumnType;
import org.diqube.function.AggregationFunction;
import org.diqube.function.Function;
import org.diqube.function.FunctionException;
import org.diqube.function.aggregate.result.IntermediaryResultValueIterator;
import org.diqube.function.aggregate.result.IntermediaryResultValueSink;
/**
* MIN function for long cols.
*
* @author Bastian Gloeckle
*/
@Function(name = MinDoubleFunction.NAME)
public class MinDoubleFunction implements AggregationFunction<Double, Double> {
public static final String NAME = "min";
private PriorityQueue<Double> minQueue = new PriorityQueue<>();
private Map<Double, Integer> valueCount = new HashMap<>();
@Override
public String getNameLowerCase() {
return NAME;
}
@Override
public void addIntermediary(IntermediaryResultValueIterator intermediary) {
double min = (Double) intermediary.next();
int count = valueCount.merge(min, 1, (a, b) -> a + b);
if (count == 1)
minQueue.add(min);
}
@Override
public void removeIntermediary(IntermediaryResultValueIterator intermediary) {
double min = (Double) intermediary.next();
Integer count = valueCount.compute(min, (k, v) -> (v == null || v <= 1) ? null : (v - 1));
if (count == null || count == 0)
minQueue.remove(min);
}
@Override
public void addValues(ValueProvider<Double> valueProvider) {
Double[] values = valueProvider.getValues();
OptionalDouble min = Stream.of(values).mapToDouble(Double::doubleValue).min();
// no need to maintain valueCount when addValues is called.
if (min.isPresent()) {
if (minQueue.isEmpty() || min.getAsDouble() < minQueue.peek())
minQueue.add(min.getAsDouble());
}
}
@Override
public void populateIntermediary(IntermediaryResultValueSink res) throws FunctionException {
res.pushValue(calculate());
}
@Override
public Double calculate() throws FunctionException {
Double res = minQueue.peek();
if (res == null)
return Double.MAX_VALUE;
return res;
}
@Override
public ColumnType getOutputType() {
return ColumnType.DOUBLE;
}
@Override
public ColumnType getInputType() {
return ColumnType.DOUBLE;
}
@Override
public void provideConstantParameter(int idx, Object value) throws FunctionException {
// noop.
}
@Override
public boolean needsActualValues() {
return true;
}
}