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https://issues.apache.org/jira/browse/FLINK-3613?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15201239#comment-15201239
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Fabian Hueske commented on FLINK-3613:
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Hi [~tlisonbee], welcome to the Flink community!
Adding more aggregation functions is a very good place to start, IMO.
As you observed, the current [[AggregationFunction}} interface is very basic
and quite limited. Since this is marked as an {{@Internal}} API it can be
changed without worrying about backwards compatibility.
How about you design a new interface and sketch a brief design doc?
Btw. FLINK-2144 is about the streaming API whereas this issue addresses the
DataSet batch API. I'm not aware of another JIRA that proposes to add more
aggregation functions to the DataSet API or anybody working this.
Thanks, Fabian
> Add standard deviation, mean, variance to list of Aggregations
> --------------------------------------------------------------
>
> Key: FLINK-3613
> URL: https://issues.apache.org/jira/browse/FLINK-3613
> Project: Flink
> Issue Type: Improvement
> Reporter: Todd Lisonbee
> Priority: Minor
>
> Implement standard deviation, mean, variance for
> org.apache.flink.api.java.aggregation.Aggregations
> Ideally implementation should be single pass and numerically stable.
> References:
> "Scalable and Numerically Stable Descriptive Statistics in SystemML", Tian et
> al, International Conference on Data Engineering 2012
> http://dl.acm.org/citation.cfm?id=2310392
> "The Kahan summation algorithm (also known as compensated summation) reduces
> the numerical errors that occur when adding a sequence of finite precision
> floating point numbers. Numerical errors arise due to truncation and
> rounding. These errors can lead to numerical instability when calculating
> variance."
> https://en.wikipedia.org/wiki/Kahan_summation_algorithm
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