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https://issues.apache.org/jira/browse/SPARK-20790?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16014723#comment-16014723
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David Eis edited comment on SPARK-20790 at 5/17/17 8:41 PM:
------------------------------------------------------------
See
https://github.com/apache/spark/pull/5314/files#diff-be65dd1d6adc53138156641b610fcadaR1118
ls.add is only called if rating > 0, which is not what was done prior to the
commit, nor does it represent what is conveyed in the comment on the previous
line.
To reproduce, you can run ALS with implicit feedback with a ratings matrix with
any negative values and it will be identical to running with the same ratings
matrix with the negative values zeroed out.
was (Author: davidjeis):
See
https://github.com/apache/spark/pull/5314/files#diff-be65dd1d6adc53138156641b610fcadaR1118
ls.add is only called if rating > 0, which is not what was done prior to the
commit, nor does it represent what is conveyed in the comment on the previous
line.
To reproduce, you can run with a ratings matrix with any negative values and it
will be identical to running with the same ratings matrix with the negative
values zeroed out.
> ALS with implicit feedback ignores negative values
> --------------------------------------------------
>
> Key: SPARK-20790
> URL: https://issues.apache.org/jira/browse/SPARK-20790
> Project: Spark
> Issue Type: Bug
> Components: ML, MLlib
> Affects Versions: 1.3.1, 1.4.0, 1.4.1, 1.5.0, 1.5.1, 1.5.2, 1.6.0, 1.6.1,
> 1.6.2, 1.6.3, 2.0.0, 2.0.1, 2.0.2, 2.1.0, 2.1.1
> Reporter: David Eis
>
> The refactorization that was done in
> https://github.com/apache/spark/pull/5314/files introduced a bug, whereby for
> implicit feedback negative ratings just get ignored. Prior to that commit
> they were not ignored, but the absolute value was used as the confidence and
> the preference was set to 0. The preservation of comments and absolute value
> indicate that this was unintentional.
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