/*
* 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.flink.api.java.operators;
import org.apache.flink.api.common.InvalidProgramException;
import org.apache.flink.api.common.functions.GroupReduceFunction;
import org.apache.flink.api.common.functions.ReduceFunction;
import org.apache.flink.api.common.operators.Order;
import org.apache.flink.api.common.typeinfo.TypeInformation;
import org.apache.flink.api.java.DataSet;
import org.apache.flink.api.java.aggregation.Aggregations;
import org.apache.flink.api.java.functions.FirstReducer;
import org.apache.flink.api.java.functions.SelectByMaxFunction;
import org.apache.flink.api.java.functions.SelectByMinFunction;
import org.apache.flink.api.java.typeutils.TupleTypeInfo;
import org.apache.flink.api.java.typeutils.TypeExtractor;
public class UnsortedGrouping<T> extends Grouping<T> {
public UnsortedGrouping(DataSet<T> set, Keys<T> keys) {
super(set, keys);
}
// --------------------------------------------------------------------------------------------
// Operations / Transformations
// --------------------------------------------------------------------------------------------
/**
* Applies an Aggregate transformation on a grouped {@link org.apache.flink.api.java.tuple.Tuple} {@link DataSet}.<br/>
* <b>Note: Only Tuple DataSets can be aggregated.</b>
* The transformation applies a built-in {@link Aggregations Aggregation} on a specified field
* of a Tuple group. Additional aggregation functions can be added to the resulting
* {@link AggregateOperator} by calling {@link AggregateOperator#and(Aggregations, int)}.
*
* @param agg The built-in aggregation function that is computed.
* @param field The index of the Tuple field on which the aggregation function is applied.
* @return An AggregateOperator that represents the aggregated DataSet.
*
* @see org.apache.flink.api.java.tuple.Tuple
* @see Aggregations
* @see AggregateOperator
* @see DataSet
*/
public AggregateOperator<T> aggregate(Aggregations agg, int field) {
return new AggregateOperator<T>(this, agg, field);
}
/**
* Syntactic sugar for aggregate (SUM, field)
* @param field The index of the Tuple field on which the aggregation function is applied.
* @return An AggregateOperator that represents the summed DataSet.
*
* @see org.apache.flink.api.java.operators.AggregateOperator
*/
public AggregateOperator<T> sum (int field) {
return this.aggregate (Aggregations.SUM, field);
}
/**
* Syntactic sugar for aggregate (MAX, field)
* @param field The index of the Tuple field on which the aggregation function is applied.
* @return An AggregateOperator that represents the max'ed DataSet.
*
* @see org.apache.flink.api.java.operators.AggregateOperator
*/
public AggregateOperator<T> max (int field) {
return this.aggregate (Aggregations.MAX, field);
}
/**
* Syntactic sugar for aggregate (MIN, field)
* @param field The index of the Tuple field on which the aggregation function is applied.
* @return An AggregateOperator that represents the min'ed DataSet.
*
* @see org.apache.flink.api.java.operators.AggregateOperator
*/
public AggregateOperator<T> min (int field) {
return this.aggregate (Aggregations.MIN, field);
}
/**
* Applies a Reduce transformation on a grouped {@link DataSet}.<br/>
* For each group, the transformation consecutively calls a {@link org.apache.flink.api.common.functions.RichReduceFunction}
* until only a single element for each group remains.
* A ReduceFunction combines two elements into one new element of the same type.
*
* @param reducer The ReduceFunction that is applied on each group of the DataSet.
* @return A ReduceOperator that represents the reduced DataSet.
*
* @see org.apache.flink.api.common.functions.RichReduceFunction
* @see ReduceOperator
* @see DataSet
*/
public ReduceOperator<T> reduce(ReduceFunction<T> reducer) {
if (reducer == null) {
throw new NullPointerException("Reduce function must not be null.");
}
return new ReduceOperator<T>(this, reducer);
}
/**
* Applies a GroupReduce transformation on a grouped {@link DataSet}.<br/>
* The transformation calls a {@link org.apache.flink.api.common.functions.RichGroupReduceFunction} for each group of the DataSet.
* A GroupReduceFunction can iterate over all elements of a group and emit any
* number of output elements including none.
*
* @param reducer The GroupReduceFunction that is applied on each group of the DataSet.
* @return A GroupReduceOperator that represents the reduced DataSet.
*
* @see org.apache.flink.api.common.functions.RichGroupReduceFunction
* @see GroupReduceOperator
* @see DataSet
*/
public <R> GroupReduceOperator<T, R> reduceGroup(GroupReduceFunction<T, R> reducer) {
if (reducer == null) {
throw new NullPointerException("GroupReduce function must not be null.");
}
TypeInformation<R> resultType = TypeExtractor.getGroupReduceReturnTypes(reducer, this.getDataSet().getType());
return new GroupReduceOperator<T, R>(this, resultType, reducer);
}
/**
* Returns a new set containing the first n elements in this grouped {@link DataSet}.<br/>
* @param n The desired number of elements for each group.
* @return A ReduceGroupOperator that represents the DataSet containing the elements.
*/
public GroupReduceOperator<T, T> first(int n) {
if(n < 1) {
throw new InvalidProgramException("Parameter n of first(n) must be at least 1.");
}
return reduceGroup(new FirstReducer<T>(n));
}
/**
* Applies a special case of a reduce transformation (minBy) on a grouped {@link DataSet}.<br/>
* The transformation consecutively calls a {@link ReduceFunction}
* until only a single element remains which is the result of the transformation.
* A ReduceFunction combines two elements into one new element of the same type.
*
* @param fields Keys taken into account for finding the minimum.
* @return A {@link ReduceOperator} representing the minimum.
*/
@SuppressWarnings({ "unchecked", "rawtypes" })
public ReduceOperator<T> minBy(int... fields) {
// Check for using a tuple
if(!this.dataSet.getType().isTupleType()) {
throw new InvalidProgramException("Method minBy(int) only works on tuples.");
}
return new ReduceOperator<T>(this, new SelectByMinFunction(
(TupleTypeInfo) this.dataSet.getType(), fields));
}
/**
* Applies a special case of a reduce transformation (maxBy) on a grouped {@link DataSet}.<br/>
* The transformation consecutively calls a {@link ReduceFunction}
* until only a single element remains which is the result of the transformation.
* A ReduceFunction combines two elements into one new element of the same type.
*
* @param fields Keys taken into account for finding the minimum.
* @return A {@link ReduceOperator} representing the minimum.
*/
@SuppressWarnings({ "unchecked", "rawtypes" })
public ReduceOperator<T> maxBy(int... fields) {
// Check for using a tuple
if(!this.dataSet.getType().isTupleType()) {
throw new InvalidProgramException("Method maxBy(int) only works on tuples.");
}
return new ReduceOperator<T>(this, new SelectByMaxFunction(
(TupleTypeInfo) this.dataSet.getType(), fields));
}
// --------------------------------------------------------------------------------------------
// Group Operations
// --------------------------------------------------------------------------------------------
/**
* Sorts {@link org.apache.flink.api.java.tuple.Tuple} elements within a group on the specified field in the specified {@link Order}.</br>
* <b>Note: Only groups of Tuple elements and Pojos can be sorted.</b><br/>
* Groups can be sorted by multiple fields by chaining {@link #sortGroup(int, Order)} calls.
*
* @param field The Tuple field on which the group is sorted.
* @param order The Order in which the specified Tuple field is sorted.
* @return A SortedGrouping with specified order of group element.
*
* @see org.apache.flink.api.java.tuple.Tuple
* @see Order
*/
public SortedGrouping<T> sortGroup(int field, Order order) {
return new SortedGrouping<T>(this.dataSet, this.keys, field, order);
}
/**
* Sorts Pojos within a group on the specified field in the specified {@link Order}.</br>
* <b>Note: Only groups of Tuple elements and Pojos can be sorted.</b><br/>
* Groups can be sorted by multiple fields by chaining {@link #sortGroup(String, Order)} calls.
*
* @param field The Tuple or Pojo field on which the group is sorted.
* @param order The Order in which the specified field is sorted.
* @return A SortedGrouping with specified order of group element.
*
* @see Order
*/
public SortedGrouping<T> sortGroup(String field, Order order) {
return new SortedGrouping<T>(this.dataSet, this.keys, field, order);
}
}