[jira] [Commented] (SPARK-7240) Covariance for DataFrames

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

    [ https://issues.apache.org/jira/browse/SPARK-7240?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14522745#comment-14522745 ] 

Apache Spark commented on SPARK-7240:
-------------------------------------

User 'brkyvz' has created a pull request for this issue:
https://github.com/apache/spark/pull/5825

> Covariance for DataFrames
> -------------------------
>
>                 Key: SPARK-7240
>                 URL: https://issues.apache.org/jira/browse/SPARK-7240
>             Project: Spark
>          Issue Type: Sub-task
>          Components: SQL
>            Reporter: Xiangrui Meng
>            Assignee: Burak Yavuz
>
> This JIRA is for computing stable covariance between two columns. The method `cov` should live under `df.stat` (similar to `na`).
> {code}
> df.stat.cov(col1, col2): Double
> {code}
> Stable algorithm: http://en.wikipedia.org/wiki/Algorithms_for_calculating_variance#Covariance
> UDAF support will be added later. Then users can do
> {code}
> df.groupBy("gender").agg(cov("age", "salary").as("cov_age_salary"))
> {code}



--
This message was sent by Atlassian JIRA
(v6.3.4#6332)

---------------------------------------------------------------------
To unsubscribe, e-mail: issues-unsubscribe@spark.apache.org
For additional commands, e-mail: issues-help@spark.apache.org