| /** |
| * 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 com.datatorrent.api.DefaultOutputPort; |
| |
| import com.datatorrent.lib.util.AbstractBaseNNonUniqueOperatorMap; |
| |
| /** |
| * This operator takes an input stream of key value pairs is ordered by key, |
| * and the bottom N of the ordered tuples per key are emitted on port "bottom" at the end of window. |
| * <p> |
| * Input stream of key value pairs is ordered by key, and bottom N of the |
| * ordered tuples per key are emitted on port "bottom" at the end of window |
| * </p> |
| * <p> |
| * This is an end of window operator. At the end of window all data is flushed. |
| * Thus the data set is windowed and no history is kept of previous windows<br> |
| * The operator assumes that the key, val pairs in the incoming tuple is |
| * immutable. If the tuple is mutable users should override cloneKey(), and |
| * cloneValue()<br> |
| * <br> |
| * <b>Ports</b>:<br> |
| * <b>data</b>: expects Map<K,V><br> |
| * <b>bottom</b>: emits HashMap<K, ArrayList<V>><br> |
| * <br> |
| * <b>Properties</b>:<br> |
| * <b>N</b>: The number of top values to be emitted per key<br> |
| * <br> |
| * <b>Specific compile time checks are</b>:<br> |
| * N: Has to be >= 1<br> |
| * <br> |
| * </p> |
| * |
| * @displayName Bottom N |
| * @category Stats and Aggregations |
| * @tags filter, rank, key value |
| * |
| * @since 0.3.3 |
| */ |
| public class BottomNMap<K, V> extends AbstractBaseNNonUniqueOperatorMap<K, V> |
| { |
| /** |
| * The output port on which the bottom N tuples for each key are emitted. |
| */ |
| public final transient DefaultOutputPort<HashMap<K, ArrayList<V>>> bottom = new DefaultOutputPort<HashMap<K, ArrayList<V>>>() |
| { |
| @Override |
| public Unifier<HashMap<K, ArrayList<V>>> getUnifier() |
| { |
| BottomNUnifier<K, V> unifier = new BottomNUnifier<K, V>(); |
| unifier.setN(getN()); |
| return unifier; |
| } |
| }; |
| |
| /** |
| * Ascending is set to false as we are looking for Bottom N |
| * |
| * @return false |
| */ |
| @Override |
| public boolean isAscending() |
| { |
| return false; |
| } |
| |
| /** |
| * Emits tuple to port "bottom" |
| * |
| * @param tuple |
| */ |
| @Override |
| public void emit(HashMap<K, ArrayList<V>> tuple) |
| { |
| bottom.emit(tuple); |
| } |
| |
| /** |
| * Bottom N values to be returned. |
| * @param val Bottom N values to be returned. |
| */ |
| @Override |
| public void setN(int val) |
| { |
| super.setN(val); |
| } |
| } |