| /* |
| * 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.wayang.basic.operators; |
| |
| import java.util.Optional; |
| import org.apache.commons.lang3.Validate; |
| import org.apache.wayang.core.api.Configuration; |
| import org.apache.wayang.core.function.FunctionDescriptor; |
| import org.apache.wayang.core.function.ReduceDescriptor; |
| import org.apache.wayang.core.function.TransformationDescriptor; |
| import org.apache.wayang.core.optimizer.cardinality.CardinalityEstimator; |
| import org.apache.wayang.core.optimizer.cardinality.DefaultCardinalityEstimator; |
| import org.apache.wayang.core.plan.wayangplan.UnaryToUnaryOperator; |
| import org.apache.wayang.core.types.DataSetType; |
| |
| /** |
| * This operator groups the elements of a data set and aggregates the groups. |
| */ |
| public class ReduceByOperator<Type, Key> extends UnaryToUnaryOperator<Type, Type> { |
| |
| protected final TransformationDescriptor<Type, Key> keyDescriptor; |
| |
| protected final ReduceDescriptor<Type> reduceDescriptor; |
| |
| /** |
| * Creates a new instance. |
| */ |
| public ReduceByOperator(FunctionDescriptor.SerializableFunction<Type, Key> keyFunction, |
| FunctionDescriptor.SerializableBinaryOperator<Type> reduceDescriptor, |
| Class<Key> keyClass, |
| Class<Type> typeClass) { |
| this(new TransformationDescriptor<>(keyFunction, typeClass, keyClass), |
| new ReduceDescriptor<>(reduceDescriptor, typeClass)); |
| } |
| |
| /** |
| * Creates a new instance. |
| * |
| * @param keyDescriptor describes how to extract the key from data units |
| * @param reduceDescriptor describes the reduction to be performed on the elements |
| */ |
| public ReduceByOperator(TransformationDescriptor<Type, Key> keyDescriptor, |
| ReduceDescriptor<Type> reduceDescriptor) { |
| this(keyDescriptor, reduceDescriptor, DataSetType.createDefault(keyDescriptor.getInputType())); |
| } |
| |
| /** |
| * Creates a new instance. |
| * |
| * @param keyDescriptor describes how to extract the key from data units |
| * @param reduceDescriptor describes the reduction to be performed on the elements |
| * @param type type of the reduce elements (i.e., type of {@link #getInput()} and {@link #getOutput()}) |
| */ |
| public ReduceByOperator(TransformationDescriptor<Type, Key> keyDescriptor, |
| ReduceDescriptor<Type> reduceDescriptor, |
| DataSetType<Type> type) { |
| super(type, type, true); |
| this.keyDescriptor = keyDescriptor; |
| this.reduceDescriptor = reduceDescriptor; |
| } |
| |
| /** |
| * Copies an instance (exclusive of broadcasts). |
| * |
| * @param that that should be copied |
| */ |
| public ReduceByOperator(ReduceByOperator<Type, Key> that) { |
| super(that); |
| this.keyDescriptor = that.getKeyDescriptor(); |
| this.reduceDescriptor = that.getReduceDescriptor(); |
| } |
| |
| public DataSetType<Type> getType() { |
| return this.getInputType(); |
| } |
| |
| public TransformationDescriptor<Type, Key> getKeyDescriptor() { |
| return this.keyDescriptor; |
| } |
| |
| public ReduceDescriptor<Type> getReduceDescriptor() { |
| return this.reduceDescriptor; |
| } |
| |
| |
| @Override |
| public Optional<CardinalityEstimator> createCardinalityEstimator( |
| final int outputIndex, |
| final Configuration configuration) { |
| Validate.inclusiveBetween(0, this.getNumOutputs() - 1, outputIndex); |
| // TODO: Come up with a decent way to estimate the "distinctness" of reduction keys. |
| return Optional.of(new DefaultCardinalityEstimator( |
| 0.5d, |
| 1, |
| this.isSupportingBroadcastInputs(), |
| inputCards -> (long) (inputCards[0] * 0.1))); |
| } |
| } |