DoubleValueSum.java
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上传日期:2018-01-08
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文件大小:2k
- /**
- * 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.mapred.lib.aggregate;
- import java.util.ArrayList;
- /**
- * This class implements a value aggregator that sums up a sequence of double
- * values.
- *
- */
- public class DoubleValueSum implements ValueAggregator {
- double sum = 0;
- /**
- * The default constructor
- *
- */
- public DoubleValueSum() {
- reset();
- }
- /**
- * add a value to the aggregator
- *
- * @param val
- * an object whose string representation represents a double value.
- *
- */
- public void addNextValue(Object val) {
- this.sum += Double.parseDouble(val.toString());
- }
- /**
- * add a value to the aggregator
- *
- * @param val
- * a double value.
- *
- */
- public void addNextValue(double val) {
- this.sum += val;
- }
- /**
- * @return the string representation of the aggregated value
- */
- public String getReport() {
- return "" + sum;
- }
- /**
- * @return the aggregated value
- */
- public double getSum() {
- return this.sum;
- }
- /**
- * reset the aggregator
- */
- public void reset() {
- sum = 0;
- }
- /**
- * @return return an array of one element. The element is a string
- * representation of the aggregated value. The return value is
- * expected to be used by the a combiner.
- */
- public ArrayList<String> getCombinerOutput() {
- ArrayList<String> retv = new ArrayList<String>(1);
- retv.add("" + sum);
- return retv;
- }
- }