/**
* 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;
import org.apache.hadoop.hive.ql.exec.NumericUDAF;
import org.apache.hadoop.hive.ql.exec.UDAFEvaluator;
import org.apache.hadoop.hive.serde2.io.DoubleWritable;
import org.apache.hadoop.io.Text;
public class UDAFAvg extends NumericUDAF {
public static class UDAFAvgEvaluator implements UDAFEvaluator {
private long mCount;
private double mSum;
public UDAFAvgEvaluator() {
super();
init();
}
public void init() {
mSum = 0;
mCount = 0;
}
public boolean iterate(DoubleWritable o) {
if (o != null) {
mSum += o.get();
mCount ++;
}
return true;
}
public Text terminatePartial() {
// This is SQL standard - average of zero items should be null.
return mCount == 0 ? null : new Text(String.valueOf(mSum) + '/' + String.valueOf(mCount));
}
public boolean merge(Text o) {
if (o != null) {
String s = o.toString();
int pos = s.indexOf('/');
assert(pos != -1);
mSum += Double.parseDouble(s.substring(0, pos));
mCount += Long.parseLong(s.substring(pos+1));
}
return true;
}
public DoubleWritable terminate() {
// This is SQL standard - average of zero items should be null.
return mCount == 0 ? null : new DoubleWritable(mSum / mCount);
}
}
}