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From "Yanbo Liang (JIRA)" <j...@apache.org>
Subject [jira] [Resolved] (SPARK-21306) OneVsRest Conceals Columns That May Be Relevant To Underlying Classifier
Date Fri, 28 Jul 2017 02:25:00 GMT

     [ https://issues.apache.org/jira/browse/SPARK-21306?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Yanbo Liang resolved SPARK-21306.
---------------------------------
       Resolution: Fixed
    Fix Version/s: 2.3.0
                   2.2.1
                   2.1.2
                   2.0.3

> OneVsRest Conceals Columns That May Be Relevant To Underlying Classifier
> ------------------------------------------------------------------------
>
>                 Key: SPARK-21306
>                 URL: https://issues.apache.org/jira/browse/SPARK-21306
>             Project: Spark
>          Issue Type: Bug
>          Components: ML
>    Affects Versions: 2.1.1
>            Reporter: Cathal Garvey
>            Assignee: Yan Facai (颜发才)
>            Priority: Critical
>              Labels: classification, ml
>             Fix For: 2.0.3, 2.1.2, 2.2.1, 2.3.0
>
>
> Hi folks, thanks for Spark! :)
> I've been learning to use `ml` and `mllib`, and I've encountered a block while trying
to use `ml.classification.OneVsRest` with `ml.classification.LogisticRegression`. Basically,
[here in the code|https://github.com/apache/spark/blob/master/mllib/src/main/scala/org/apache/spark/ml/classification/OneVsRest.scala#L320],
only two columns are being extracted and fed to the underlying classifiers.. however with
some configurations, more than two columns are required.
> Specifically: I want to do multiclass learning with Logistic Regression, on a very imbalanced
dataset. In my dataset, I have lots of imbalances, so I was planning to use weights. I set
a column, `"weight"`, as the inverse frequency of each field, and I configured my `LogisticRegression`
class to use this column, then put it in a `OneVsRest` wrapper.
> However, `OneVsRest` strips all but two columns out of a dataset before training, so
I get an error from within `LogisticRegression` that it can't find the `"weight"` column.
> It would be nice to have this fixed! I can see a few ways, but a very conservative fix
would be to include a parameter in `OneVsRest.fit` for additional columns to `select` before
passing to the underlying model.
> Thanks!



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