[jira] [Comment Edited] (SPARK-12806) Support SQL expressions extracting values from VectorUDT

["Franklyn Dsouza (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/SPARK-12806?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16061718#comment-16061718 ] 

Franklyn Dsouza edited comment on SPARK-12806 at 6/24/17 2:54 PM:
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[~mengxr] could you please take a look ? we have had to jumpy through a lot of hoops to work around this.


was (Author: franklyndsouza):
[~mengxr] can we get this fixed ?

> Support SQL expressions extracting values from VectorUDT
> --------------------------------------------------------
>
>                 Key: SPARK-12806
>                 URL: https://issues.apache.org/jira/browse/SPARK-12806
>             Project: Spark
>          Issue Type: Improvement
>          Components: MLlib, SQL
>    Affects Versions: 1.6.0
>            Reporter: Feynman Liang
>
> Use cases exist where a specific index within a {{VectorUDT}} column of a {{DataFrame}} is required. For example, we may be interested in extracting a specific class probability from the {{probabilityCol}} of a {{LogisticRegression}} to compute losses. However, if {{probability}} is a column of {{df}} with type {{VectorUDT}}, the following code fails:
> {code}
> df.select("probability.0")
> AnalysisException: u"Can't extract value from probability"
> {code}
> thrown from {{sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/complexTypeExtractors.scala}}.
> {{VectorUDT}} essentially wraps a {{StructType}}, hence one would expect it to support value extraction Expressions in an analogous way.



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