org.apache.hadoop.hive.ql.udf.generic.GenericUDAFPercentRank Maven / Gradle / Ivy
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* Licensed to the Apache Software Foundation (ASF) under one
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* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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
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package org.apache.hadoop.hive.ql.udf.generic;
import java.util.ArrayList;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.hadoop.hive.ql.exec.Description;
import org.apache.hadoop.hive.ql.exec.WindowFunctionDescription;
import org.apache.hadoop.hive.ql.metadata.HiveException;
import org.apache.hadoop.hive.serde2.io.DoubleWritable;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.ObjectInspectorFactory;
import org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorFactory;
import org.apache.hadoop.io.IntWritable;
@WindowFunctionDescription(
description = @Description(
name = "percent_rank",
value = "_FUNC_(x) PERCENT_RANK is similar to CUME_DIST, but it uses rank values rather " +
"than row counts in its numerator. PERCENT_RANK of a row is calculated as: " +
"(rank of row in its partition - 1) / (number of rows in the partition - 1)"
),
supportsWindow = false,
pivotResult = true,
rankingFunction = true,
impliesOrder = true
)
public class GenericUDAFPercentRank extends GenericUDAFRank {
static final Log LOG = LogFactory.getLog(GenericUDAFPercentRank.class.getName());
@Override
protected GenericUDAFAbstractRankEvaluator createEvaluator() {
return new GenericUDAFPercentRankEvaluator();
}
public static class GenericUDAFPercentRankEvaluator extends GenericUDAFAbstractRankEvaluator {
@Override
public ObjectInspector init(Mode m, ObjectInspector[] parameters) throws HiveException {
super.init(m, parameters);
return ObjectInspectorFactory.getStandardListObjectInspector(
PrimitiveObjectInspectorFactory.writableDoubleObjectInspector);
}
@Override
public Object terminate(AggregationBuffer agg) throws HiveException {
ArrayList ranks = ((RankBuffer) agg).rowNums;
double sz = ranks.size();
if (sz > 1) {
sz = sz - 1;
}
ArrayList pranks = new ArrayList(ranks.size());
for (IntWritable i : ranks) {
double pr = ((double) i.get() - 1) / sz;
pranks.add(new DoubleWritable(pr));
}
return pranks;
}
}
}