/**
* 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.math.BigDecimal;
import java.math.BigInteger;
import java.util.function.Supplier;
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;
import org.diqube.function.aggregate.util.BigDecimalHelper;
/**
* Average function that takes Longs as input.
*
* @author Bastian Gloeckle
*/
@Function(name = AvgLongFunction.NAME)
public class AvgLongFunction implements AggregationFunction<Long, Double> {
public static final String NAME = "avg";
private static final Supplier<BigDecimal> ZERO_DECIMAL = () -> new BigDecimal("0.000000");
private static final Supplier<BigInteger> ZERO_INT = () -> BigInteger.valueOf(0l);
private BigInteger sum = ZERO_INT.get();
private long count = 0L;
@Override
public String getNameLowerCase() {
return NAME;
}
@Override
public void addIntermediary(IntermediaryResultValueIterator intermediary) {
BigInteger otherSum = (BigInteger) intermediary.next();
long otherCount = (Long) intermediary.next();
if (otherCount == 0)
return;
sum = sum.add(otherSum);
count += otherCount;
}
@Override
public void removeIntermediary(IntermediaryResultValueIterator intermediary) {
BigInteger otherSum = (BigInteger) intermediary.next();
long otherCount = (Long) intermediary.next();
if (otherCount == 0)
return;
if (otherCount == count) {
sum = ZERO_INT.get();
count = 0;
return;
}
sum = sum.subtract(otherSum);
count -= otherCount;
}
@Override
public void addValues(ValueProvider<Long> valueProvider) {
Long[] values = valueProvider.getValues();
for (Long value : values) {
sum = sum.add(BigInteger.valueOf(value));
count++;
}
}
@Override
public void populateIntermediary(IntermediaryResultValueSink res) throws FunctionException {
res.pushValue(sum);
res.pushValue(count);
}
@Override
public Double calculate() throws FunctionException {
BigDecimal sumDec = BigDecimalHelper.zeroCreate().add(new BigDecimal(sum));
return sumDec.divide(new BigDecimal(count), BigDecimalHelper.defaultMathContext()).doubleValue();
}
@Override
public ColumnType getOutputType() {
return ColumnType.DOUBLE;
}
@Override
public ColumnType getInputType() {
return ColumnType.LONG;
}
@Override
public void provideConstantParameter(int idx, Object value) throws FunctionException {
// noop.
}
@Override
public boolean needsActualValues() {
return true;
}
}