/*
* 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.metadata.MetadataManager;
import com.facebook.presto.spi.block.Block;
import com.facebook.presto.spi.block.BlockBuilder;
import com.facebook.presto.spi.block.BlockBuilderStatus;
import com.facebook.presto.spi.type.StandardTypes;
import com.facebook.presto.sql.tree.QualifiedName;
import com.google.common.collect.ImmutableList;
import org.apache.commons.math3.stat.descriptive.moment.StandardDeviation;
import static com.facebook.presto.spi.type.BigintType.BIGINT;
public class TestLongStdDevAggregation
extends AbstractTestAggregationFunction
{
protected final MetadataManager metadata = new MetadataManager();
@Override
public Block getSequenceBlock(int start, int length)
{
BlockBuilder blockBuilder = BIGINT.createBlockBuilder(new BlockBuilderStatus());
for (int i = start; i < start + length; i++) {
BIGINT.writeLong(blockBuilder, i);
}
return blockBuilder.build();
}
@Override
public InternalAggregationFunction getFunction()
{
return metadata.resolveFunction(new QualifiedName("stddev_samp"), ImmutableList.of(StandardTypes.BIGINT), false).getAggregationFunction();
}
@Override
public Number getExpectedValue(int start, int length)
{
if (length < 2) {
return null;
}
double[] values = new double[length];
for (int i = 0; i < length; i++) {
values[i] = start + i;
}
StandardDeviation stdDev = new StandardDeviation();
return stdDev.evaluate(values);
}
}