| /* |
| * Copyright (c) 2013 DataTorrent, Inc. ALL Rights Reserved. |
| * |
| * Licensed 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 com.datatorrent.api.DefaultInputPort; |
| import com.datatorrent.api.DefaultOutputPort; |
| import com.datatorrent.api.annotation.OperatorAnnotation; |
| import com.datatorrent.api.annotation.OutputPortFieldAnnotation; |
| |
| import com.datatorrent.lib.util.AbstractBaseFrequentKey; |
| |
| /** |
| * This operator filters the incoming stream of values by emitting the value or values (if there is a tie) |
| * that occurred the fewest number of times within each window to the output port "list". |
| * One of the values is emitted to the output port "least" at the end of each window. |
| * <p> |
| * Occurrences of each tuple is counted and at the end of window any of the least frequent tuple is emitted on output port 'least' |
| * All keys with same least frequency value least are emitted on output port 'list'.<br> |
| * This module is an end of window module<br> |
| * In case of a tie any of the least key would be emitted. The list port would however have all the tied keys |
| * <br> |
| * <b>StateFull : Yes, </b> tuple are compared across application window(s). <br> |
| * <b>Partitions : Yes, </b> least keys are unified on output port. <br> |
| * <br> |
| * <b>Ports</b>:<br> |
| * <b>data</b>: expects K<br> |
| * <b>least</b>: emits HashMap<K,Integer>(1), Where K is the least occurring key in the window. |
| * In case of tie any of the least key would be emitted<br> |
| * <b>list</b>: emits ArrayList<HashMap<K,Integer>(1)>, Where the list includes all the keys that are least frequent<br> |
| * <br> |
| * </p> |
| * |
| * @displayName Emit Least Frequent Value |
| * @category Algorithmic |
| * @tags filter, count |
| * |
| * @since 0.3.3 |
| */ |
| |
| @OperatorAnnotation(partitionable = true) |
| public class LeastFrequentKey<K> extends AbstractBaseFrequentKey<K> |
| { |
| /** |
| * The input port on which tuples are received. |
| */ |
| public final transient DefaultInputPort<K> data = new DefaultInputPort<K>() |
| { |
| /** |
| * Calls super.processTuple(tuple) |
| */ |
| @Override |
| public void process(K tuple) |
| { |
| processTuple(tuple); |
| } |
| }; |
| |
| /** |
| * The output port on which one of the tuples, |
| * which occurred the least number of times, |
| * is emitted. |
| */ |
| @OutputPortFieldAnnotation(optional=true) |
| public final transient DefaultOutputPort<HashMap<K, Integer>> least = new DefaultOutputPort<HashMap<K, Integer>>() |
| { |
| @SuppressWarnings({ "rawtypes", "unchecked" }) |
| @Override |
| public Unifier<HashMap<K, Integer>> getUnifier() |
| { |
| return new LeastFrequentKeyUnifier<K>(); |
| } |
| }; |
| |
| /** |
| * The output port on which all the tuples, |
| * which occurred the least number of times, |
| * is emitted. |
| */ |
| @OutputPortFieldAnnotation(optional=true) |
| public final transient DefaultOutputPort<ArrayList<HashMap<K, Integer>>> list = new DefaultOutputPort<ArrayList<HashMap<K, Integer>>>() |
| { |
| @SuppressWarnings({ "rawtypes", "unchecked" }) |
| @Override |
| public Unifier<ArrayList<HashMap<K, Integer>>> getUnifier() |
| { |
| return new LeastFrequentKeyArrayUnifier<K>(); |
| } |
| }; |
| |
| /** |
| * Emits tuple on port "least" |
| * @param tuple |
| */ |
| @Override |
| public void emitTuple(HashMap<K, Integer> tuple) |
| { |
| least.emit(tuple); |
| } |
| |
| /** |
| * returns val1 < val2 |
| * @param val1 |
| * @param val2 |
| * @return val1 < val2 |
| */ |
| @Override |
| public boolean compareCount(int val1, int val2) |
| { |
| return val1 < val2; |
| } |
| |
| /** |
| * Emits tuple on port "list" |
| * @param tlist |
| */ |
| @Override |
| public void emitList(ArrayList<HashMap<K, Integer>> tlist) |
| { |
| list.emit(tlist); |
| } |
| } |