[
https://issues.apache.org/jira/browse/PIG-1150?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12903634#action_12903634
]
Dmitriy V. Ryaboy commented on PIG-1150:
----------------------------------------
I won't have time before the 30th.
BTW one doesn't even need a udf if using the sum of squares approach.. :-) just
generate the square and the sum in the foreach (it will perform the algebraic
decomposition automatically)
> VAR() Variance UDF
> ------------------
>
> Key: PIG-1150
> URL: https://issues.apache.org/jira/browse/PIG-1150
> Project: Pig
> Issue Type: New Feature
> Affects Versions: 0.5.0
> Environment: UDF, written in Pig 0.5 contrib/
> Reporter: Russell Jurney
> Assignee: Dmitriy V. Ryaboy
> Fix For: 0.8.0
>
> Attachments: var.patch
>
>
> I've implemented a UDF in Pig 0.5 that implements Algebraic and calculates
> variance in a distributed manner, based on the AVG() builtin. It works by
> calculating the count, sum and sum of squares, as described here:
> http://en.wikipedia.org/wiki/Algorithms_for_calculating_variance#Parallel_algorithm
> Is this a worthwhile contribution? Taking the square root of this value
> using the contrib SQRT() function gives Standard Deviation, which is missing
> from Pig.
--
This message is automatically generated by JIRA.
-
You can reply to this email to add a comment to the issue online.
