srowen commented on a change in pull request #17084: [SPARK-24103][ML][MLLIB] 
ML Evaluators should use weight column - added weight column for binary 
classification evaluator
URL: https://github.com/apache/spark/pull/17084#discussion_r259648266
 
 

 ##########
 File path: 
mllib/src/test/scala/org/apache/spark/mllib/evaluation/BinaryClassificationMetricsSuite.scala
 ##########
 @@ -82,6 +82,34 @@ class BinaryClassificationMetricsSuite extends 
SparkFunSuite with MLlibTestSpark
     validateMetrics(metrics, thresholds, rocCurve, prCurve, f1, f2, 
precisions, recalls)
   }
 
+  test("binary evaluation metrics with weights") {
+    val w1 = 1.5
+    val w2 = 0.7
+    val w3 = 0.4
+    val scoreAndLabelsWithWeights = sc.parallelize(
+      Seq((0.1, 0.0, w1), (0.1, 1.0, w2), (0.4, 0.0, w1), (0.6, 0.0, w3),
+        (0.6, 1.0, w2), (0.6, 1.0, w2), (0.8, 1.0, w1)), 2)
+    val metrics = new BinaryClassificationMetrics(scoreAndLabelsWithWeights, 0)
+    val thresholds = Seq(0.8, 0.6, 0.4, 0.1)
+    val numTruePositives =
+      Seq(1.0 * w1, 1.0 * w1 + 2.0 * w2, 1.0 * w1 + 2.0 * w2, 3.0 * w2 + 1.0 * 
w1)
+    val numFalsePositives = Seq(0.0, 1.0 * w3, 1.0 * w1 + 1.0 * w3, 1.0 * w3 + 
2.0 * w1)
+    val numPositives = 3 * w2 + 1 * w1
+    val numNegatives = 2 * w1 + w3
+    val precisions = numTruePositives.zip(numFalsePositives).map { case (t, f) 
=>
+      t.toDouble / (t + f)
+    }
+    val recalls = numTruePositives.map(t => t / numPositives)
+    val fpr = numFalsePositives.map(f => f / numNegatives)
+    val rocCurve = Seq((0.0, 0.0)) ++ fpr.zip(recalls) ++ Seq((1.0, 1.0))
+    val pr = recalls.zip(precisions)
+    val prCurve = Seq((0.0, 1.0)) ++ pr
 
 Review comment:
   You don't need to change this, just an aside, but you can write in cases 
like this `(0.0, 1.0) +: pr` I know the other code is written like this so 
don't change it.

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