/*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package com.facebook.presto.operator.aggregation;
import com.facebook.presto.operator.PageBuilder;
import com.facebook.presto.spi.block.BlockEncodingSerde;
import com.google.common.base.Optional;
import com.google.common.collect.ImmutableList;
import org.apache.commons.math3.distribution.BinomialDistribution;
import org.testng.annotations.Test;
import java.util.Random;
import static com.facebook.presto.operator.aggregation.AggregationTestUtils.approximateAggregationWithinErrorBound;
import static com.facebook.presto.operator.aggregation.AggregationTestUtils.assertApproximateAggregation;
import static com.facebook.presto.operator.aggregation.LongSumAggregation.LONG_SUM;
import static com.facebook.presto.serde.TestingBlockEncodingManager.createTestingBlockEncodingManager;
import static com.facebook.presto.spi.type.BigintType.BIGINT;
import static org.testng.Assert.assertTrue;
public class TestBootstrappedAggregation
{
@Test
public void testSum()
throws Exception
{
int sum = 1_000;
PageBuilder builder = new PageBuilder(ImmutableList.of(BIGINT, BIGINT));
Random rand = new Random(0);
for (int i = 0; i < sum; i++) {
if (rand.nextDouble() < 0.5) {
builder.getBlockBuilder(0).appendLong(1);
builder.getBlockBuilder(1).appendLong(2);
}
}
AggregationFunction function = new DeterministicBootstrappedAggregation(createTestingBlockEncodingManager(), LONG_SUM);
assertApproximateAggregation(function, 1, 0.99, (double) sum, builder.build());
}
@Test
public void testErrorBound()
throws Exception
{
int trials = 20;
BinomialDistribution binomial = new BinomialDistribution(trials, 0.5);
int successes = 0;
Random rand = new Random(0);
for (int i = 0; i < trials; i++) {
int sum = 1_000;
PageBuilder builder = new PageBuilder(ImmutableList.of(BIGINT, BIGINT));
for (int j = 0; j < sum; j++) {
if (rand.nextDouble() < 0.5) {
builder.getBlockBuilder(0).appendLong(1);
builder.getBlockBuilder(1).appendLong(2);
}
}
AggregationFunction function = new DeterministicBootstrappedAggregation(createTestingBlockEncodingManager(), LONG_SUM);
successes += approximateAggregationWithinErrorBound(function, 1, 0.5, (double) sum, builder.build()) ? 1 : 0;
}
// Since we used a confidence of 0.5, successes should have a binomial distribution B(n=20, p=0.5)
assertTrue(binomial.inverseCumulativeProbability(0.01) < successes && successes < binomial.inverseCumulativeProbability(0.99));
}
private static class DeterministicBootstrappedAggregation
extends BootstrappedAggregation
{
public DeterministicBootstrappedAggregation(BlockEncodingSerde blockEncodingManager, AggregationFunction function)
{
super(blockEncodingManager, function);
}
@Override
public Accumulator createAggregation(Optional<Integer> maskChannel, Optional<Integer> sampleWeightChannel, double confidence, int... argumentChannels)
{
return createDeterministicAggregation(maskChannel, sampleWeightChannel.get(), confidence, 0, argumentChannels);
}
@Override
public Accumulator createIntermediateAggregation(double confidence)
{
return createDeterministicIntermediateAggregation(confidence, 0);
}
@Override
public GroupedAccumulator createGroupedAggregation(Optional<Integer> maskChannel, Optional<Integer> sampleWeightChannel, double confidence, int... argumentChannels)
{
return createDeterministicGroupedAggregation(maskChannel, sampleWeightChannel.get(), confidence, 0, argumentChannels);
}
@Override
public GroupedAccumulator createGroupedIntermediateAggregation(double confidence)
{
return createDeterministicGroupedIntermediateAggregation(confidence, 0);
}
}
}