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https://issues.apache.org/jira/browse/FLINK-3664?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15227168#comment-15227168
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ASF GitHub Bot commented on FLINK-3664:
---------------------------------------
GitHub user tlisonbee opened a pull request:
https://github.com/apache/flink/pull/1855
[FLINK-3664] Create method to easily summarize a DataSet of Tuples
Adding summarize() method in DataSetUtils that will supply a number of
single pass statistics for DataSets of Tuples.
Summary statistics depend on the type being summarized:
- Numeric types (Integer, IntValue, Float, Double, etc): min, max, mean,
variance, standard deviation, NaN count, Infinity count, totalCount, etc.
- String, StringValue: minLength, maxLength, meanLength, emptyCount,
totalCount
- Boolean, BooleanValue: trueCount, falseCount, totalCount.
Example usage:
`Dataset<Tuple3<Double, String, Boolean>> input = // [...]`
`Tuple3<NumericColumnSummary,StringColumnSummary, BooleanColumnSummary>
summary = DataSetUtils.summarize(input)`
`summary.f0.getStandardDeviation()`
`summary.f1.getMaxLength()`
Uses the Kahan summation algorithm to avoid numeric instability. The
algorithm is described in: "Scalable and Numerically Stable Descriptive
Statistics in SystemML", Tian et al, International Conference on Data
Engineering 2012.
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/tlisonbee/flink FLINK-3664
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/flink/pull/1855.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #1855
----
commit 65f54df532829994a8be240a27b9138d01a186b5
Author: Todd Lisonbee <[email protected]>
Date: 2016-04-05T05:51:12Z
[FLINK-3664] Create DataSetUtils method to easily summarize a DataSet of
Tuples
----
> Create a method to easily Summarize a DataSet
> ---------------------------------------------
>
> Key: FLINK-3664
> URL: https://issues.apache.org/jira/browse/FLINK-3664
> Project: Flink
> Issue Type: Improvement
> Reporter: Todd Lisonbee
> Attachments: DataSet-Summary-Design-March2016-v1.txt
>
>
> Here is an example:
> {code}
> /**
> * Summarize a DataSet of Tuples by collecting single pass statistics for all
> columns
> */
> public Tuple summarize()
> Dataset<Tuple3<Double, String, Boolean>> input = // [...]
> Tuple3<DoubleColumnSummary,StringColumnSummary,BooleanColumnSummary> summary
> = input.summarize()
> summary.getField(0).stddev()
> summary.getField(1).maxStringLength()
> {code}
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