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Posted to issues@spark.apache.org by "Marco Gaido (JIRA)" <ji...@apache.org> on 2018/10/29 15:25:00 UTC
[jira] [Commented] (SPARK-25870) RandomSplit with seed gives
different results depending on column order
[ https://issues.apache.org/jira/browse/SPARK-25870?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16667346#comment-16667346 ]
Marco Gaido commented on SPARK-25870:
-------------------------------------
Why do you consider this a bug? They are 2 different dataframes, there is no insurance that setting the seed on 2 different dataframes makes Spark returning the same result.
> RandomSplit with seed gives different results depending on column order
> -----------------------------------------------------------------------
>
> Key: SPARK-25870
> URL: https://issues.apache.org/jira/browse/SPARK-25870
> Project: Spark
> Issue Type: Bug
> Components: SQL
> Affects Versions: 2.3.2
> Reporter: Daniel
> Priority: Minor
> Original Estimate: 96h
> Remaining Estimate: 96h
>
> Co-discovered by Zhihui Hong (zhong01@syr.edu):
> {{If you run the following example, the resulting dataframe will have different rows even though the have the same seed:}}
> {{from pyspark.sql import SparkSession, functions as fn}}
> {{spark = SparkSession.builder.getOrCreate()}}{{ }}
> {{df = spark.range(0, 10).withColumn('r', (fn.rand()*10).cast('int'))}}
> {{# sample 1}}
> {{df.randomSplit([0.8, 0.2], seed=0)[0].show(5)}}{{ }}
> {{# sample 2}}
> {{df.select('r', 'id').randomSplit([0.8, 0.2], seed=0)[0].show(5)}}
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