[jira] [Commented] (FLINK-1901) Create sample operator for Dataset

[ASF GitHub Bot (JIRA)]

    [ 
https://issues.apache.org/jira/browse/FLINK-1901?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14696632#comment-14696632
 ] 

ASF GitHub Bot commented on FLINK-1901:
---------------------------------------

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

    https://github.com/apache/flink/pull/949#discussion_r37054584
  
    --- Diff: 
flink-tests/src/test/scala/org/apache/flink/api/scala/operators/SampleITCase.scala
 ---
    @@ -0,0 +1,166 @@
    +/*
    + * 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.operators
    +
    +import java.util.{List => JavaList, Random}
    +
    +import org.apache.flink.api.scala._
    +import org.apache.flink.api.scala.util.CollectionDataSets
    +import 
org.apache.flink.test.util.MultipleProgramsTestBase.TestExecutionMode
    +import org.apache.flink.test.util.{MultipleProgramsTestBase, TestBaseUtils}
    +import org.junit.Assert._
    +import org.junit.runner.RunWith
    +import org.junit.runners.Parameterized
    +import org.junit.{Before, After, Test}
    +
    +import scala.collection.JavaConverters._
    +
    +@RunWith(classOf[Parameterized])
    +class SampleITCase(mode: TestExecutionMode) extends 
MultipleProgramsTestBase(mode) {
    +  private val RNG: Random = new Random
    +
    +  private var result: JavaList[String] = null;
    +
    +  @Before
    +  def initiate {
    +    ExecutionEnvironment.getExecutionEnvironment.setParallelism(5)
    +  }
    +
    +  @After
    +  def after() = {
    +    TestBaseUtils.containsResultAsText(result, getSourceStrings)
    +  }
    +
    +  @Test
    +  @throws(classOf[Exception])
    +  def testSamplerWithFractionWithoutReplacement {
    +    verifySamplerWithFractionWithoutReplacement(0d)
    +    verifySamplerWithFractionWithoutReplacement(0.2d)
    +    verifySamplerWithFractionWithoutReplacement(1.0d)
    +  }
    +
    +  @Test
    +  @throws(classOf[Exception])
    +  def testSamplerWithFractionWithReplacement {
    +    verifySamplerWithFractionWithReplacement(0d)
    +    verifySamplerWithFractionWithReplacement(0.2d)
    +    verifySamplerWithFractionWithReplacement(1.0d)
    +    verifySamplerWithFractionWithReplacement(2.0d)
    +  }
    +
    +  @Test
    +  @throws(classOf[Exception])
    +  def testSamplerWithSizeWithoutReplacement {
    +    verifySamplerWithFixedSizeWithoutReplacement(0)
    +    verifySamplerWithFixedSizeWithoutReplacement(2)
    +    verifySamplerWithFixedSizeWithoutReplacement(21)
    +  }
    +
    +  @Test
    +  @throws(classOf[Exception])
    +  def testSamplerWithSizeWithReplacement {
    +    verifySamplerWithFixedSizeWithReplacement(0)
    +    verifySamplerWithFixedSizeWithReplacement(2)
    +    verifySamplerWithFixedSizeWithReplacement(21)
    +  }
    +
    +  @throws(classOf[Exception])
    +  private def verifySamplerWithFractionWithoutReplacement(fraction: 
Double) {
    +    verifySamplerWithFractionWithoutReplacement(fraction, RNG.nextLong)
    +  }
    +
    +  @throws(classOf[Exception])
    +  private def verifySamplerWithFractionWithoutReplacement(fraction: 
Double, seed: Long) {
    +    verifySamplerWithFraction(false, fraction, seed)
    +  }
    +
    +  @throws(classOf[Exception])
    +  private def verifySamplerWithFractionWithReplacement(fraction: Double) {
    +    verifySamplerWithFractionWithReplacement(fraction, RNG.nextLong)
    +  }
    +
    +  @throws(classOf[Exception])
    +  private def verifySamplerWithFractionWithReplacement(fraction: Double, 
seed: Long) {
    +    verifySamplerWithFraction(true, fraction, seed)
    +  }
    +
    +  @throws(classOf[Exception])
    +  private def verifySamplerWithFraction(withReplacement: Boolean, 
fraction: Double, seed: Long) {
    +    val ds = getSourceDataSet()
    +    val sampled = ds.sample(withReplacement, fraction, seed)
    +    result = sampled.collect.asJava
    --- End diff --
    
    Thanks, I missed that.


> Create sample operator for Dataset
> ----------------------------------
>
>                 Key: FLINK-1901
>                 URL: https://issues.apache.org/jira/browse/FLINK-1901
>             Project: Flink
>          Issue Type: Improvement
>          Components: Core
>            Reporter: Theodore Vasiloudis
>            Assignee: Chengxiang Li
>
> In order to be able to implement Stochastic Gradient Descent and a number of 
> other machine learning algorithms we need to have a way to take a random 
> sample from a Dataset.
> We need to be able to sample with or without replacement from the Dataset, 
> choose the relative or exact size of the sample, set a seed for 
> reproducibility, and support sampling within iterations.



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