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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (FLINK-3650) Add maxBy/minBy to Scala DataSet API
Date Tue, 14 Jun 2016 20:45:30 GMT

    [ https://issues.apache.org/jira/browse/FLINK-3650?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15330560#comment-15330560
] 

ASF GitHub Bot commented on FLINK-3650:
---------------------------------------

Github user fhueske commented on a diff in the pull request:

    https://github.com/apache/flink/pull/1856#discussion_r67052986
  
    --- Diff: flink-scala/src/main/scala/org/apache/flink/api/scala/SelectByMaxFunction.scala
---
    @@ -0,0 +1,59 @@
    +/*
    + * 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.scala
    +
    +import org.apache.flink.api.common.functions.ReduceFunction
    +import org.apache.flink.api.common.typeinfo.TypeInformation
    +import org.apache.flink.api.java.typeutils.TupleTypeInfoBase
    +import org.apache.flink.annotation.Internal
    +
    +/**
    +  * SelectByMaxFunction to work with Scala tuples
    +  */
    +@Internal
    +class SelectByMaxFunction[T](t : TypeInformation[T], val f : Array[Int]) extends  ReduceFunction[T]{
    +  private val fields = f;
    +  private val typeInf = t;
    +  for(f1 <- fields) {
    +    if (f1 < 0 || f1 >= typeInf.getArity()) {
    +      throw new IndexOutOfBoundsException(
    +        "MinReduceFunction field position " + f1 + " is out of range.");
    +    }
    +    // Check whether type is comparable
    +
    +    if (!typeInf.asInstanceOf[TupleTypeInfoBase[T]].getTypeAt(f1).isKeyType()) {
    +      throw new java.lang.IllegalArgumentException(
    +        "MinReduceFunction supports only key(Comparable) types.");
    +    }
    +  }
    +  override def reduce(value1: T, value2: T): T = {
    +    for (f <- fields) {
    +      val element1  = value1.asInstanceOf[Product].productElement(f).asInstanceOf[Comparable[Any]]
    --- End diff --
    
    indention


> Add maxBy/minBy to Scala DataSet API
> ------------------------------------
>
>                 Key: FLINK-3650
>                 URL: https://issues.apache.org/jira/browse/FLINK-3650
>             Project: Flink
>          Issue Type: Improvement
>          Components: Java API, Scala API
>    Affects Versions: 1.1.0
>            Reporter: Till Rohrmann
>            Assignee: ramkrishna.s.vasudevan
>
> The stable Java DataSet API contains the API calls {{maxBy}} and {{minBy}}. These methods
are not supported by the Scala DataSet API. These methods should be added in order to have
a consistent API.



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