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// Copyright Yahoo. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
package com.yahoo.searchlib.aggregation;
import com.yahoo.searchlib.expression.FloatResultNode;
import com.yahoo.searchlib.expression.ResultNode;
import com.yahoo.vespa.objects.Deserializer;
import com.yahoo.vespa.objects.ObjectVisitor;
import com.yahoo.vespa.objects.Serializer;
/**
* @author bjorncs
*/
public class StandardDeviationAggregationResult extends AggregationResult {
public static final int classId = registerClass(0x4000 + 89, StandardDeviationAggregationResult.class);
private long count;
private double sum;
private double sumOfSquared;
/**
* Constructor used for deserialization. Will be instantiated with a default sketch.
*/
@SuppressWarnings("unused")
public StandardDeviationAggregationResult() {
this(0, 0.0, 0.0);
}
public StandardDeviationAggregationResult(long count, double sum, double sumOfSquared) {
this.count = count;
this.sum = sum;
this.sumOfSquared = sumOfSquared;
}
public double getStandardDeviation() {
if (count == 0) {
return 0;
} else {
double variance = (sumOfSquared - sum * sum / count) / count;
return Math.sqrt(variance);
}
}
@Override
public ResultNode getRank() {
return new FloatResultNode(getStandardDeviation());
}
@Override
protected void onMerge(AggregationResult obj) {
StandardDeviationAggregationResult other = (StandardDeviationAggregationResult) obj;
count += other.count;
sum += other.sum;
sumOfSquared += other.sumOfSquared;
}
@Override
protected boolean equalsAggregation(AggregationResult obj) {
StandardDeviationAggregationResult other = (StandardDeviationAggregationResult) obj;
return count == this.count && sum == other.sum && sumOfSquared == other.sumOfSquared;
}
@Override
protected void onSerialize(Serializer buf) {
super.onSerialize(buf);
buf.putLong(null, count);
buf.putDouble(null, sum);
buf.putDouble(null, sumOfSquared);
}
@Override
protected void onDeserialize(Deserializer buf) {
super.onDeserialize(buf);
count = buf.getLong(null);
sum = buf.getDouble(null);
sumOfSquared = buf.getDouble(null);
}
@Override
protected int onGetClassId() {
return classId;
}
@Override
public void visitMembers(ObjectVisitor visitor) {
super.visitMembers(visitor);
visitor.visit("count", count);
visitor.visit("sum", sum);
visitor.visit("sumOfSquared", sumOfSquared);
}
}
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