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From "ASF GitHub Bot (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (FLINK-1901) Create sample operator for Dataset
Date Fri, 31 Jul 2015 15:44:04 GMT

    [ https://issues.apache.org/jira/browse/FLINK-1901?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14649372#comment-14649372
] 

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

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

    https://github.com/apache/flink/pull/949#discussion_r35985704
  
    --- Diff: flink-core/src/main/java/org/apache/flink/api/common/operators/util/ReservoirSamplerWithoutReplacement.java
---
    @@ -0,0 +1,100 @@
    +/*
    + * 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.common.operators.util;
    +
    +import com.google.common.base.Preconditions;
    +
    +import java.util.ArrayList;
    +import java.util.Iterator;
    +import java.util.List;
    +import java.util.Random;
    +
    +/**
    + * A simple in memory implementation of Reservoir Sampling without replacement, and with
only one pass through
    + * the input iteration whose size is unpredictable.
    + * This implementation refers to the Algorithm R described in "Random Sampling with a
Reservoir" Vitter, 1985.
    --- End diff --
    
    Maybe add again a link to the paper if available.


> 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 size of the sample, and set a seed for reproducibility.



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