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Histogram.java
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Histogram.java
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/*
* 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.flink.api.common.accumulators;
import org.apache.flink.annotation.Public;
import java.util.Map;
import java.util.TreeMap;
/**
* Histogram accumulator, which builds a histogram in a distributed manner. Implemented as a
* Integer->Integer TreeMap, so that the entries are sorted according to the values.
*
* <p>This class does not extend to continuous values later, because it makes no attempt to put the
* data in bins.
*/
@Public
public class Histogram implements Accumulator<Integer, TreeMap<Integer, Integer>> {
private static final long serialVersionUID = 1L;
private TreeMap<Integer, Integer> treeMap = new TreeMap<Integer, Integer>();
@Override
public void add(Integer value) {
Integer current = treeMap.get(value);
Integer newValue = (current != null ? current : 0) + 1;
this.treeMap.put(value, newValue);
}
@Override
public TreeMap<Integer, Integer> getLocalValue() {
return this.treeMap;
}
@Override
public void merge(Accumulator<Integer, TreeMap<Integer, Integer>> other) {
// Merge the values into this map
for (Map.Entry<Integer, Integer> entryFromOther : other.getLocalValue().entrySet()) {
Integer ownValue = this.treeMap.get(entryFromOther.getKey());
if (ownValue == null) {
this.treeMap.put(entryFromOther.getKey(), entryFromOther.getValue());
} else {
this.treeMap.put(entryFromOther.getKey(), entryFromOther.getValue() + ownValue);
}
}
}
@Override
public void resetLocal() {
this.treeMap.clear();
}
@Override
public String toString() {
return this.treeMap.toString();
}
@Override
public Accumulator<Integer, TreeMap<Integer, Integer>> clone() {
Histogram result = new Histogram();
result.treeMap = new TreeMap<Integer, Integer>(treeMap);
return result;
}
}