| /** |
| * 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 com.datatorrent.lib.algo; |
| |
| import java.util.ArrayList; |
| import java.util.HashMap; |
| import java.util.Map; |
| |
| import com.datatorrent.api.Context.OperatorContext; |
| import com.datatorrent.api.DefaultOutputPort; |
| import com.datatorrent.api.Operator.Unifier; |
| |
| /** |
| * This unifier is used by the LeastFrequentKey operator in order to merge the output of the "list" output port. |
| * <p></p> |
| * @displayName Emit Least Frequent Value |
| * @category Algorithmic |
| * @tags filter, count |
| * |
| * @since 0.3.3 |
| */ |
| public class LeastFrequentKeyArrayUnifier<K> implements Unifier<ArrayList<HashMap<K, Integer>>> |
| { |
| /** |
| * Key/Least value map. |
| */ |
| private HashMap<K, Integer> leastMap = new HashMap<K, Integer>(); |
| |
| /** |
| * The output port on which the least frequent tuple is emitted. |
| */ |
| public final transient DefaultOutputPort<HashMap<K, Integer>> mergedport = new DefaultOutputPort<HashMap<K, Integer>>(); |
| |
| @Override |
| public void beginWindow(long arg0) |
| { |
| // TODO Auto-generated method stub |
| |
| } |
| |
| @Override |
| public void endWindow() |
| { |
| mergedport.emit(leastMap); |
| leastMap.clear(); |
| } |
| |
| @Override |
| public void setup(OperatorContext arg0) |
| { |
| // TODO Auto-generated method stub |
| |
| } |
| |
| @Override |
| public void teardown() |
| { |
| // TODO Auto-generated method stub |
| |
| } |
| |
| @Override |
| public void process(ArrayList<HashMap<K, Integer>> tuples) |
| { |
| for (HashMap<K, Integer> tuple : tuples) { |
| for (Map.Entry<K, Integer> entry : tuple.entrySet()) { |
| Integer value = entry.getValue(); |
| if (leastMap.containsKey(entry.getKey())) { |
| if (leastMap.get(entry.getKey()) < value) { |
| value = leastMap.remove(entry.getKey()); |
| } else { |
| leastMap.remove(entry.getKey()); |
| } |
| } |
| leastMap.put(entry.getKey(), value); |
| } |
| } |
| } |
| |
| } |