[jira] [Assigned] (SPARK-11581) Example mllib code in documentation incorrectly computes MSE

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

     [ https://issues.apache.org/jira/browse/SPARK-11581?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Apache Spark reassigned SPARK-11581:
------------------------------------

    Assignee:     (was: Apache Spark)

> Example mllib code in documentation incorrectly computes MSE
> ------------------------------------------------------------
>
>                 Key: SPARK-11581
>                 URL: https://issues.apache.org/jira/browse/SPARK-11581
>             Project: Spark
>          Issue Type: Bug
>          Components: Documentation
>    Affects Versions: 1.5.1
>            Reporter: Brian Webb
>            Priority: Trivial
>              Labels: starter
>
> The example Java code at the bottom of the mllib-decision-tree web page shows how to compute MSE on the test data. However, there is a bug in the code. The code currently divides by data.count(), but it should instead divide by the count of testData, testData.count().
> http://spark.apache.org/docs/latest/mllib-decision-tree.html
> Double testMSE =
>   predictionAndLabel.map(new Function<Tuple2<Double, Double>, Double>() {
>     @Override
>     public Double call(Tuple2<Double, Double> pl) {
>       Double diff = pl._1() - pl._2();
>       return diff * diff;
>     }
>   }).reduce(new Function2<Double, Double, Double>() {
>     @Override
>     public Double call(Double a, Double b) {
>       return a + b;
>     }
>   }) / data.count();
> System.out.println("Test Mean Squared Error: " + testMSE);



--
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