[jira] [Commented] (DATAFU-60) Support NDCG calculation within a UDF

["Eyal Allweil (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/DATAFU-60?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16284984#comment-16284984 ] 

Eyal Allweil commented on DATAFU-60:
------------------------------------

Hi [~jhartman], I know it's been years, but do you think you'll get back to this? If not someone else will finish it off, since there isn't much left to do.

> Support NDCG calculation within a UDF
> -------------------------------------
>
>                 Key: DATAFU-60
>                 URL: https://issues.apache.org/jira/browse/DATAFU-60
>             Project: DataFu
>          Issue Type: New Feature
>            Reporter: Joshua Hartman
>              Labels: features
>         Attachments: DATAFU-60-v2.patch, DATAFU-60.patch
>
>   Original Estimate: 48h
>  Remaining Estimate: 48h
>
> Ndcg is a common evaluation metric for the quality of a list of items presented to a user. It is an especially common metric used in the search literature.
> This feature request is to implement a udf to calculate ndcg. 
> NDCG can be calculated using any function to represent the value of a position. Several useful functions should be available as part of the datafu library. First is the standard 1/logarithmic discounting factor. Another option should be the ability to supply a custom positional value for any range of positions in the case that a positional "value" is already well understood. However, the actual discounting function used should be easily pluggable in the event something custom is needed



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