| /* |
| * 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.HashMap; |
| |
| import com.datatorrent.api.DefaultOutputPort; |
| import com.datatorrent.api.annotation.OperatorAnnotation; |
| |
| import com.datatorrent.lib.util.AbstractBaseFrequentKeyValueMap; |
| |
| /** |
| * This operator filters the incoming stream of key value pairs by finding the value or values (if there is a tie), |
| * for each key, that occur the largest number of times within each window. |
| * Each key and its corresponding most values are emitted at the end of each window. |
| * <p> |
| * Occurrences of all values for each key is counted and at the end of window the most frequent values are emitted on output port least per key |
| * </p> |
| * <p> |
| * This module is an end of window module<br> |
| * <br> |
| * <b>Ports</b>:<br> |
| * <b>data</b>: expects HashMap<K,V><br> |
| * <b>most</b>: emits HashMap<String, HashMap<String, Integer>>(1)<br> |
| * <br> |
| * <br> |
| * <b>Properties</b>: None<br> |
| * <br> |
| * <b>Compile time checks</b>: None<br> |
| * <b>Specific run time checks</b>: None <br> |
| * <br> |
| * <b>Benchmarks</b>: Blast as many tuples as possible in inline mode<br> |
| * <table border="1" cellspacing=1 cellpadding=1 summary="Benchmark table for MostFrequentKeyValueMap<K,V> operator template"> |
| * <tr><th>In-Bound</th><th>Out-bound</th><th>Comments</th></tr> |
| * <tr><td><b>> 30 Million K,V pairs/s</b></td><td>Emits only 1 tuple per window per key</td><td>In-bound throughput is the main determinant of performance. |
| * The benchmark was done with immutable objects. If K or V are mutable the benchmark may be lower</td></tr> |
| * </table><br> |
| * </p> |
| * <p> |
| * <b>Function Table (K=String,V=Integer);</b>: |
| * <table border="1" cellspacing=1 cellpadding=1 summary="Function table for MostFrequentKeyValueMap<K,V> operator template"> |
| * <tr><th rowspan=2>Tuple Type (api)</th><th>In-bound (process)</th><th>Out-bound (emit)</th></tr> |
| * <tr><th><i>data</i>(HashMap<K,V>)</th><th><i>most</i>(HashMap<K,HashMap<Integer>>)</th></tr> |
| * <tr><td>Begin Window (beginWindow())</td><td>N/A</td><td>N/A</td></tr> |
| * <tr><td>Data (process())</td><td>{a=1,b=5,c=110}</td><td></td></tr> |
| * <tr><td>Data (process())</td><td>{a=55,c=2000,b=45}</td><td></td></tr> |
| * <tr><td>Data (process())</td><td>{d=2}</td><td></td></tr> |
| * <tr><td>Data (process())</td><td>{a=55,b=5,c=22}</td><td></td></tr> |
| * <tr><td>Data (process())</td><td>{h=20,a=2,z=5}</td><td></td></tr> |
| * <tr><td>Data (process())</td><td>{a=4,c=110}</td><td></td></tr> |
| * <tr><td>Data (process())</td><td>{a=4,z=5}</td><td></td></tr> |
| * <tr><td>End Window (endWindow())</td><td>N/A</td><td>{a={4=2,55=2},b={5=2},c={110=2},d={2=1},h={20=1},z={5=2}</td></tr> |
| * </table> |
| * <br> |
| * <br> |
| * </p> |
| * |
| * @displayName Emit Most Frequent Keyval Pair |
| * @category Algorithmic |
| * @tags filter, key value, count |
| * |
| * @since 0.3.2 |
| */ |
| |
| @OperatorAnnotation(partitionable = false) |
| public class MostFrequentKeyValueMap<K, V> extends AbstractBaseFrequentKeyValueMap<K, V> |
| { |
| /** |
| * The output port which emits a map from keys to their most values. |
| */ |
| public final transient DefaultOutputPort<HashMap<K, HashMap<V, Integer>>> most = new DefaultOutputPort<HashMap<K, HashMap<V, Integer>>>(); |
| |
| /** |
| * returns val1 < val2 |
| * @param val1 |
| * @param val2 |
| * @return val1 > val2 |
| */ |
| @Override |
| public boolean compareValue(int val1, int val2) |
| { |
| return (val1 > val2); |
| } |
| |
| /** |
| * Emits tuple on port "most" |
| * @param tuple is emitted on port "most" |
| */ |
| @Override |
| public void emitTuple(HashMap<K, HashMap<V, Integer>> tuple) |
| { |
| most.emit(tuple); |
| } |
| } |