[jira] [Commented] (SPARK-3568) Add metrics for ranking algorithms

["Apache Spark (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/SPARK-3568?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14160022#comment-14160022 ] 

Apache Spark commented on SPARK-3568:
-------------------------------------

User 'coderxiang' has created a pull request for this issue:
https://github.com/apache/spark/pull/2667

> Add metrics for ranking algorithms
> ----------------------------------
>
>                 Key: SPARK-3568
>                 URL: https://issues.apache.org/jira/browse/SPARK-3568
>             Project: Spark
>          Issue Type: New Feature
>          Components: MLlib
>            Reporter: Shuo Xiang
>            Assignee: Shuo Xiang
>
> Include common metrics for ranking algorithms (http://www-nlp.stanford.edu/IR-book/), including:
>  - Mean Average Precision
>  - Precision@n: top-n precision
>  - Discounted cumulative gain (DCG) and NDCG 
> This implementation attempts to create a new class called *RankingMetrics* under *org.apache.spark.mllib.evaluation*, which accepts input (prediction and label pairs) as *RDD[Array[Double], Array[Double]]*. The following methods will be implemented:
> {code:title=RankingMetrics.scala|borderStyle=solid}
> class RankingMetrics(predictionAndLabels: RDD[(Array[Double], Array[Double])]) {
>   /* Returns the precsion@k for each query */
>   lazy val precAtK: RDD[Array[Double]]
>   /* Returns the average precision for each query */
>   lazy val avePrec: RDD[Double]
>   /*Returns the mean average precision (MAP) of all the queries*/
>   lazy val meanAvePrec: Double
>   /*Returns the normalized discounted cumulative gain for each query */
>   lazy val ndcg: RDD[Double]
>   /* Returns the mean NDCG of all the queries */
>   lazy val meanNdcg: Double
> }
> {code}



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