/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* 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
* 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 org.apache.hadoop.hive.ql.udf.generic;
import java.util.ArrayList;
import org.apache.hadoop.hive.ql.exec.UDFArgumentTypeException;
import org.apache.hadoop.hive.ql.exec.description;
import org.apache.hadoop.hive.ql.metadata.HiveException;
import org.apache.hadoop.hive.ql.parse.SemanticException;
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.PrimitiveObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.StructField;
import org.apache.hadoop.hive.serde2.objectinspector.StructObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.primitive.DoubleObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.primitive.LongObjectInspector;
import org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorFactory;
import org.apache.hadoop.hive.serde2.objectinspector.primitive.PrimitiveObjectInspectorUtils;
import org.apache.hadoop.hive.serde2.typeinfo.PrimitiveTypeInfo;
import org.apache.hadoop.hive.serde2.typeinfo.TypeInfo;
import org.apache.hadoop.io.LongWritable;
@description(
name = "avg",
value = "_FUNC_(x) - Returns the mean of a set of numbers"
)
public class GenericUDAFAverage implements GenericUDAFResolver {
@Override
public GenericUDAFEvaluator getEvaluator(
TypeInfo[] parameters) throws SemanticException {
if (parameters.length != 1) {
throw new UDFArgumentTypeException(parameters.length - 1,
"Exactly one argument is expected.");
}
if (parameters[0].getCategory() != ObjectInspector.Category.PRIMITIVE) {
throw new UDFArgumentTypeException(0,
"Only primitive type arguments are accepted but " + parameters[0].getTypeName() + " is passed.");
}
switch (((PrimitiveTypeInfo)parameters[0]).getPrimitiveCategory()) {
case BYTE:
case SHORT:
case INT:
case LONG:
case FLOAT:
case DOUBLE:
case STRING:
return new GenericUDAFAverageEvaluator();
case BOOLEAN:
default:
throw new UDFArgumentTypeException(0,
"Only numeric or string type arguments are accepted but " + parameters[0].getTypeName() + " is passed.");
}
}
public static class GenericUDAFAverageEvaluator extends GenericUDAFEvaluator {
// For PARTIAL1 and COMPLETE
PrimitiveObjectInspector inputOI;
// For PARTIAL2 and FINAL
StructObjectInspector soi;
StructField countField;
StructField sumField;
LongObjectInspector countFieldOI;
DoubleObjectInspector sumFieldOI;
// For PARTIAL1 and PARTIAL2
Object[] partialResult;
// For FINAL and COMPLETE
DoubleWritable result;
@Override
public ObjectInspector init(Mode m, ObjectInspector[] parameters)
throws HiveException {
assert(parameters.length == 1);
super.init(m, parameters);
// init input
if (mode == mode.PARTIAL1 || mode == mode.COMPLETE) {
inputOI = (PrimitiveObjectInspector)parameters[0];
} else {
soi = (StructObjectInspector)parameters[0];
countField = soi.getStructFieldRef("count");
sumField = soi.getStructFieldRef("sum");
countFieldOI = (LongObjectInspector)countField.getFieldObjectInspector();
sumFieldOI = (DoubleObjectInspector)sumField.getFieldObjectInspector();
}
// init output
if (mode == mode.PARTIAL1 || mode == mode.PARTIAL2) {
// The output of a partial aggregation is a struct containing
// a "long" count and a "double" sum.
ArrayList<ObjectInspector> foi = new ArrayList<ObjectInspector>();
foi.add(PrimitiveObjectInspectorFactory.writableLongObjectInspector);
foi.add(PrimitiveObjectInspectorFactory.writableDoubleObjectInspector);
ArrayList<String> fname = new ArrayList<String>();
fname.add("count");
fname.add("sum");
partialResult = new Object[2];
partialResult[0] = new LongWritable(0);
partialResult[1] = new DoubleWritable(0);
return ObjectInspectorFactory.getStandardStructObjectInspector(
fname, foi);
} else {
result = new DoubleWritable(0);
return PrimitiveObjectInspectorFactory.writableDoubleObjectInspector;
}
}
static class AverageAgg implements AggregationBuffer {
long count;
double sum;
};
@Override
public AggregationBuffer getNewAggregationBuffer() throws HiveException {
AverageAgg result = new AverageAgg();
reset(result);
return result;
}
@Override
public void reset(AggregationBuffer agg) throws HiveException {
AverageAgg myagg = (AverageAgg)agg;
myagg.count = 0;
myagg.sum = 0;
}
@Override
public void iterate(AggregationBuffer agg, Object[] parameters) throws HiveException {
assert(parameters.length == 1);
Object p = parameters[0];
if (p != null) {
AverageAgg myagg = (AverageAgg)agg;
double v = PrimitiveObjectInspectorUtils.getDouble(p,
(PrimitiveObjectInspector)inputOI);
myagg.count ++;
myagg.sum += v;
}
}
@Override
public Object terminatePartial(AggregationBuffer agg) throws HiveException {
AverageAgg myagg = (AverageAgg)agg;
((LongWritable)partialResult[0]).set(myagg.count);
((DoubleWritable)partialResult[1]).set(myagg.sum);
return partialResult;
}
@Override
public void merge(AggregationBuffer agg, Object partial) throws HiveException {
if (partial != null) {
AverageAgg myagg = (AverageAgg)agg;
Object partialCount = soi.getStructFieldData(partial, countField);
Object partialSum = soi.getStructFieldData(partial, sumField);
myagg.count += countFieldOI.get(partialCount);
myagg.sum += sumFieldOI.get(partialSum);
}
}
@Override
public Object terminate(AggregationBuffer agg) throws HiveException {
AverageAgg myagg = (AverageAgg)agg;
if (myagg.count == 0) {
return null;
} else {
result.set(myagg.sum / myagg.count);
return result;
}
}
}
}