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Brian Webb commented on SPARK-11581: ------------------------------------ Thanks guys! > 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: 1.3.1, 1.4.1, 1.5.1, 1.6.0 > Reporter: Brian Webb > Priority: Trivial > Labels: starter > Fix For: 1.4.2, 1.5.3, 1.6.0 > > > 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-unsubscr...@spark.apache.org For additional commands, e-mail: issues-h...@spark.apache.org