Github user ajaysaini725 commented on a diff in the pull request: https://github.com/apache/spark/pull/18281#discussion_r127557890 --- Diff: mllib/src/test/scala/org/apache/spark/ml/classification/OneVsRestSuite.scala --- @@ -101,6 +101,50 @@ class OneVsRestSuite extends SparkFunSuite with MLlibTestSparkContext with Defau assert(expectedMetrics.confusionMatrix ~== ovaMetrics.confusionMatrix absTol 400) } + test("one-vs-rest: tuning parallelism does not change output") { + val numClasses = 3 + val ovaPar1 = new OneVsRest() + .setClassifier(new LogisticRegression) + + val ovaModelPar1 = ovaPar1.fit(dataset) + + val transformedDatasetPar1 = ovaModelPar1.transform(dataset) + + val ovaResultsPar1 = transformedDatasetPar1.select("prediction", "label").rdd.map { + row => (row.getDouble(0), row.getDouble(1)) + } + + val ovaPar2 = new OneVsRest() + .setClassifier(new LogisticRegression) + .setParallelism(2) + + val ovaModelPar2 = ovaPar2.fit(dataset) + + val transformedDatasetPar2 = ovaModelPar2.transform(dataset) + + val ovaResultsPar2 = transformedDatasetPar2.select("prediction", "label").rdd.map { + row => (row.getDouble(0), row.getDouble(1)) + } + + val metricsPar1 = new MulticlassMetrics(ovaResultsPar1) + val metricsPar2 = new MulticlassMetrics(ovaResultsPar2) + assert(metricsPar1.confusionMatrix == metricsPar2.confusionMatrix) + + for (i <- 0 until ovaModelPar1.models.length) { + var foundCloseCoeffs = false + val currentCoeffs = ovaModelPar1.models(i) + .asInstanceOf[LogisticRegressionModel].coefficients + for (j <- 0 until ovaModelPar2.models.length) { --- End diff -- Because of the parallelism the order in which the models are written to the array might be different between runs. As a result, it is necessary to compare all pairs of models in the arrays not just models at the same indices.
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