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Posted to issues@spark.apache.org by "Hyukjin Kwon (JIRA)" <ji...@apache.org> on 2019/05/21 04:12:41 UTC

[jira] [Resolved] (SPARK-20072) Clarify ALS-WR documentation

     [ https://issues.apache.org/jira/browse/SPARK-20072?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Hyukjin Kwon resolved SPARK-20072.
----------------------------------
    Resolution: Incomplete

> Clarify ALS-WR documentation
> ----------------------------
>
>                 Key: SPARK-20072
>                 URL: https://issues.apache.org/jira/browse/SPARK-20072
>             Project: Spark
>          Issue Type: Improvement
>          Components: Documentation
>    Affects Versions: 2.1.0
>            Reporter: chris snow
>            Priority: Trivial
>              Labels: bulk-closed
>
> https://www.mail-archive.com/user@spark.apache.org/msg62590.html
> The documentation for collaborative filtering is as follows:
> ===
> Scaling of the regularization parameter
> Since v1.1, we scale the regularization parameter lambda in solving
> each least squares problem by the number of ratings the user generated
> in updating user factors, or the number of ratings the product
> received in updating product factors.
> ===
> I find this description confusing, probably because I lack a detailed
> understanding of ALS.   The wording suggest that the number of ratings
> change ("generated", "received") during solving the least squares.
> This is how I think I should be interpreting the description:
> ===
> Since v1.1, we scale the regularization parameter lambda when solving
> each least squares problem.  When updating the user factors, we scale
> the regularization parameter by the total number of ratings from the
> user.  Similarly, when updating the product factors, we scale the
> regularization parameter by the total number of ratings for the
> product.
> ===



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