Removed MonotonicityConstraint, Isotonic and Antitonic constraints. Replced by simple boolean

Author: zapletal-martin

mllib/src/main/scala/org/apache/spark/mllib/regression/IsotonicRegression.scala

@@ -18,56 +18,17 @@
 package org.apache.spark.mllib.regression
 
 import org.apache.spark.mllib.linalg.Vector
-import org.apache.spark.mllib.regression.MonotonicityConstraint.MonotonicityConstraint._
 import org.apache.spark.rdd.RDD
 
-/**
- * Monotonicity constrains for monotone regression
- * Isotonic (increasing)
- * Antitonic (decreasing)
- */
-object MonotonicityConstraint {
-
-  object MonotonicityConstraint {
-
-    sealed trait MonotonicityConstraint {
-      private[regression] def holds(
-        current: WeightedLabeledPoint,
-        next: WeightedLabeledPoint): Boolean
-    }
-
-    /**
-     * Isotonic monotonicity constraint. Increasing sequence
-     */
-    case object Isotonic extends MonotonicityConstraint {
-      override def holds(current: WeightedLabeledPoint, next: WeightedLabeledPoint): Boolean = {
-        current.label <= next.label
-      }
-    }
-
-    /**
-     * Antitonic monotonicity constrain. Decreasing sequence
-     */
-    case object Antitonic extends MonotonicityConstraint {
-      override def holds(current: WeightedLabeledPoint, next: WeightedLabeledPoint): Boolean = {
-        current.label >= next.label
-      }
-    }
-  }
-
-  val Isotonic = MonotonicityConstraint.Isotonic
-  val Antitonic = MonotonicityConstraint.Antitonic
-}
-
 /**
  * Regression model for Isotonic regression
  *
  * @param predictions Weights computed for every feature.
- * @param monotonicityConstraint specifies if the sequence is increasing or decreasing
+ * @param isotonic isotonic (increasing) or antitonic (decreasing) sequence
  */
 class IsotonicRegressionModel(
     val predictions: Seq[WeightedLabeledPoint],
-    val monotonicityConstraint: MonotonicityConstraint)
+    val isotonic: Boolean)
   extends RegressionModel {
 
   override def predict(testData: RDD[Vector]): RDD[Double] =
@@ -91,23 +52,23 @@ trait IsotonicRegressionAlgorithm
    *
    * @param predictions labels estimated using isotonic regression algorithm.
    *                    Used for predictions on new data points.
-   * @param monotonicityConstraint isotonic or antitonic
+   * @param isotonic isotonic (increasing) or antitonic (decreasing) sequence
    * @return isotonic regression model
    */
   protected def createModel(
       predictions: Seq[WeightedLabeledPoint],
-      monotonicityConstraint: MonotonicityConstraint): IsotonicRegressionModel
+      isotonic: Boolean): IsotonicRegressionModel
 
   /**
    * Run algorithm to obtain isotonic regression model
    *
    * @param input data
-   * @param monotonicityConstraint ascending or descenting
+   * @param isotonic isotonic (increasing) or antitonic (decreasing) sequence
    * @return isotonic regression model
    */
   def run(
       input: RDD[WeightedLabeledPoint],
-      monotonicityConstraint: MonotonicityConstraint): IsotonicRegressionModel
+      isotonic: Boolean): IsotonicRegressionModel
 }
 
 /**
@@ -118,16 +79,16 @@ class PoolAdjacentViolators private [mllib]
 
   override def run(
       input: RDD[WeightedLabeledPoint],
-      monotonicityConstraint: MonotonicityConstraint): IsotonicRegressionModel = {
+      isotonic: Boolean): IsotonicRegressionModel = {
     createModel(
-      parallelPoolAdjacentViolators(input, monotonicityConstraint),
-      monotonicityConstraint)
+      parallelPoolAdjacentViolators(input, isotonic),
+      isotonic)
   }
 
   override protected def createModel(
       predictions: Seq[WeightedLabeledPoint],
-      monotonicityConstraint: MonotonicityConstraint): IsotonicRegressionModel = {
-    new IsotonicRegressionModel(predictions, monotonicityConstraint)
+      isotonic: Boolean): IsotonicRegressionModel = {
+    new IsotonicRegressionModel(predictions, isotonic)
   }
 
   /**
@@ -138,12 +99,12 @@ class PoolAdjacentViolators private [mllib]
    * Method in situ mutates input array
    *
    * @param in input data
-   * @param monotonicityConstraint asc or desc
+   * @param isotonic asc or desc
    * @return result
    */
   private def poolAdjacentViolators(
       in: Array[WeightedLabeledPoint],
-      monotonicityConstraint: MonotonicityConstraint): Array[WeightedLabeledPoint] = {
+      isotonic: Boolean): Array[WeightedLabeledPoint] = {
 
     // Pools sub array within given bounds assigning weighted average value to all elements
     def pool(in: Array[WeightedLabeledPoint], start: Int, end: Int): Unit = {
@@ -159,11 +120,17 @@ class PoolAdjacentViolators private [mllib]
 
     var i = 0
 
+    val monotonicityConstrainter: (Double, Double) => Boolean = (x, y) => if(isotonic) {
+      x <= y
+    } else {
+      x >= y
+    }
+
     while(i < in.length) {
       var j = i
 
       // Find monotonicity violating sequence, if any
-      while(j < in.length - 1 && !monotonicityConstraint.holds(in(j), in(j + 1))) {
+      while(j < in.length - 1 && !monotonicityConstrainter(in(j).label, in(j + 1).label)) {
         j = j + 1
       }
 
@@ -173,7 +140,7 @@ class PoolAdjacentViolators private [mllib]
       } else {
         // Otherwise pool the violating sequence
         // And check if pooling caused monotonicity violation in previously processed points
-        while (i >= 0 && !monotonicityConstraint.holds(in(i), in(i + 1))) {
+        while (i >= 0 && !monotonicityConstrainter(in(i).label, in(i + 1).label)) {
           pool(in, i, j)
           i = i - 1
         }
@@ -190,19 +157,19 @@ class PoolAdjacentViolators private [mllib]
    * Calls Pool adjacent violators on each partition and then again on the result
    *
    * @param testData input
-   * @param monotonicityConstraint asc or desc
+   * @param isotonic isotonic (increasing) or antitonic (decreasing) sequence
    * @return result
    */
   private def parallelPoolAdjacentViolators(
       testData: RDD[WeightedLabeledPoint],
-      monotonicityConstraint: MonotonicityConstraint): Seq[WeightedLabeledPoint] = {
+      isotonic: Boolean): Seq[WeightedLabeledPoint] = {
 
     poolAdjacentViolators(
       testData
         .sortBy(_.features.toArray.head)
         .cache()
-        .mapPartitions(it => poolAdjacentViolators(it.toArray, monotonicityConstraint).toIterator)
-        .collect(), monotonicityConstraint)
+        .mapPartitions(it => poolAdjacentViolators(it.toArray, isotonic).toIterator)
+        .collect(), isotonic)
   }
 }
 
@@ -221,11 +188,11 @@ object IsotonicRegression {
    *              Each point describes a row of the data
    *              matrix A as well as the corresponding right hand side label y
    *              and weight as number of measurements
-   * @param monotonicityConstraint Isotonic (increasing) or Antitonic (decreasing) sequence
+   * @param isotonic isotonic (increasing) or antitonic (decreasing) sequence
    */
   def train(
       input: RDD[WeightedLabeledPoint],
-      monotonicityConstraint: MonotonicityConstraint = Isotonic): IsotonicRegressionModel = {
-    new PoolAdjacentViolators().run(input, monotonicityConstraint)
+      isotonic: Boolean = true): IsotonicRegressionModel = {
+    new PoolAdjacentViolators().run(input, isotonic)
   }
 }

mllib/src/test/java/org/apache/spark/mllib/regression/JavaIsotonicRegressionSuite.java

@@ -62,7 +62,7 @@ public void runIsotonicRegressionUsingConstructor() {
         new double[] {1, 2, 3, 3, 1, 6, 7, 8, 11, 9, 10, 12})).cache();
 
     IsotonicRegressionAlgorithm isotonicRegressionAlgorithm = new PoolAdjacentViolators();
-    IsotonicRegressionModel model = isotonicRegressionAlgorithm.run(testRDD.rdd(), MonotonicityConstraint.Isotonic());
+    IsotonicRegressionModel model = isotonicRegressionAlgorithm.run(testRDD.rdd(), true);
 
     List<WeightedLabeledPoint> expected = IsotonicDataGenerator
       .generateIsotonicInputAsList(
@@ -77,7 +77,7 @@ public void runIsotonicRegressionUsingStaticMethod() {
       .generateIsotonicInputAsList(
         new double[] {1, 2, 3, 3, 1, 6, 7, 8, 11, 9, 10, 12})).cache();
 
-    IsotonicRegressionModel model = IsotonicRegression.train(testRDD.rdd(), MonotonicityConstraint.Isotonic());
+    IsotonicRegressionModel model = IsotonicRegression.train(testRDD.rdd(), true);
 
     List<WeightedLabeledPoint> expected = IsotonicDataGenerator
       .generateIsotonicInputAsList(
@@ -92,7 +92,7 @@ public void testPredictJavaRDD() {
       .generateIsotonicInputAsList(
         new double[] {1, 2, 3, 3, 1, 6, 7, 8, 11, 9, 10, 12})).cache();
 
-    IsotonicRegressionModel model = IsotonicRegression.train(testRDD.rdd(), MonotonicityConstraint.Isotonic());
+    IsotonicRegressionModel model = IsotonicRegression.train(testRDD.rdd(), true);
 
     JavaRDD<Vector> vectors = testRDD.map(new Function<WeightedLabeledPoint, Vector>() {
       @Override

mllib/src/test/scala/org/apache/spark/mllib/regression/IsotonicRegressionSuite.scala

@@ -18,7 +18,6 @@
 package org.apache.spark.mllib.regression
 
 import org.apache.spark.mllib.linalg.Vectors
-import org.apache.spark.mllib.regression.MonotonicityConstraint.MonotonicityConstraint.{Antitonic, Isotonic}
 import org.apache.spark.mllib.util.{LocalClusterSparkContext, MLlibTestSparkContext}
 import org.scalatest.{Matchers, FunSuite}
 import WeightedLabeledPointConversions._
@@ -37,7 +36,7 @@ class IsotonicRegressionSuite
     val testRDD = sc.parallelize(generateIsotonicInput(1, 2, 3, 3, 1, 6, 7, 8, 11, 9, 10, 12, 14, 15, 17, 16, 17, 18, 19, 20)).cache()
 
     val alg = new PoolAdjacentViolators
-    val model = alg.run(testRDD, Isotonic)
+    val model = alg.run(testRDD, true)
 
     model.predictions should be(generateIsotonicInput(1, 2, 7d/3, 7d/3, 7d/3, 6, 7, 8, 10, 10, 10, 12, 14, 15, 16.5, 16.5, 17, 18, 19, 20))
   }
@@ -46,7 +45,7 @@ class IsotonicRegressionSuite
     val testRDD = sc.parallelize(List[WeightedLabeledPoint]()).cache()
 
     val alg = new PoolAdjacentViolators
-    val model = alg.run(testRDD, Isotonic)
+    val model = alg.run(testRDD, true)
 
     model.predictions should be(List())
   }
@@ -55,7 +54,7 @@ class IsotonicRegressionSuite
     val testRDD = sc.parallelize(generateIsotonicInput(1)).cache()
 
     val alg = new PoolAdjacentViolators
-    val model = alg.run(testRDD, Isotonic)
+    val model = alg.run(testRDD, true)
 
     model.predictions should be(generateIsotonicInput(1))
   }
@@ -64,7 +63,7 @@ class IsotonicRegressionSuite
     val testRDD = sc.parallelize(generateIsotonicInput(1, 2, 3, 4, 5)).cache()
 
     val alg = new PoolAdjacentViolators
-    val model = alg.run(testRDD, Isotonic)
+    val model = alg.run(testRDD, true)
 
     model.predictions should be(generateIsotonicInput(1, 2, 3, 4, 5))
   }
@@ -73,7 +72,7 @@ class IsotonicRegressionSuite
     val testRDD = sc.parallelize(generateIsotonicInput(5, 4, 3, 2, 1)).cache()
 
     val alg = new PoolAdjacentViolators
-    val model = alg.run(testRDD, Isotonic)
+    val model = alg.run(testRDD, true)
 
     model.predictions should be(generateIsotonicInput(3, 3, 3, 3, 3))
   }
@@ -82,7 +81,7 @@ class IsotonicRegressionSuite
     val testRDD = sc.parallelize(generateIsotonicInput(1, 2, 3, 4, 2)).cache()
 
     val alg = new PoolAdjacentViolators
-    val model = alg.run(testRDD, Isotonic)
+    val model = alg.run(testRDD, true)
 
     model.predictions should be(generateIsotonicInput(1, 2, 3, 3, 3))
   }
@@ -91,7 +90,7 @@ class IsotonicRegressionSuite
     val testRDD = sc.parallelize(generateIsotonicInput(4, 2, 3, 4, 5)).cache()
 
     val alg = new PoolAdjacentViolators
-    val model = alg.run(testRDD, Isotonic)
+    val model = alg.run(testRDD, true)
 
     model.predictions should be(generateIsotonicInput(3, 3, 3, 4, 5))
   }
@@ -100,7 +99,7 @@ class IsotonicRegressionSuite
     val testRDD = sc.parallelize(generateIsotonicInput(-1, -2, 0, 1, -1)).cache()
 
     val alg = new PoolAdjacentViolators
-    val model = alg.run(testRDD, Isotonic)
+    val model = alg.run(testRDD, true)
 
     model.predictions should be(generateIsotonicInput(-1.5, -1.5, 0, 0, 0))
   }
@@ -109,7 +108,7 @@ class IsotonicRegressionSuite
     val testRDD = sc.parallelize(generateIsotonicInput(1, 2, 3, 4, 5).reverse).cache()
 
     val alg = new PoolAdjacentViolators
-    val model = alg.run(testRDD, Isotonic)
+    val model = alg.run(testRDD, true)
 
     model.predictions should be(generateIsotonicInput(1, 2, 3, 4, 5))
   }
@@ -118,7 +117,7 @@ class IsotonicRegressionSuite
     val testRDD = sc.parallelize(generateWeightedIsotonicInput(Seq(1, 2, 3, 4, 2), Seq(1, 1, 1, 1, 2))).cache()
 
     val alg = new PoolAdjacentViolators
-    val model = alg.run(testRDD, Isotonic)
+    val model = alg.run(testRDD, true)
 
     model.predictions should be(generateWeightedIsotonicInput(Seq(1, 2, 2.75, 2.75,2.75), Seq(1, 1, 1, 1, 2)))
   }
@@ -127,7 +126,7 @@ class IsotonicRegressionSuite
     val testRDD = sc.parallelize(generateWeightedIsotonicInput(Seq(1, 2, 3, 2, 1), Seq(1, 1, 1, 0.1, 0.1))).cache()
 
     val alg = new PoolAdjacentViolators
-    val model = alg.run(testRDD, Isotonic)
+    val model = alg.run(testRDD, true)
 
     model.predictions.map(p => p.copy(label = round(p.label))) should be
       (generateWeightedIsotonicInput(Seq(1, 2, 3.3/1.2, 3.3/1.2, 3.3/1.2), Seq(1, 1, 1, 0.1, 0.1)))
@@ -137,7 +136,7 @@ class IsotonicRegressionSuite
     val testRDD = sc.parallelize(generateWeightedIsotonicInput(Seq(1, 2, 3, 2, 1), Seq(-1, 1, -3, 1, -5))).cache()
 
     val alg = new PoolAdjacentViolators
-    val model = alg.run(testRDD, Isotonic)
+    val model = alg.run(testRDD, true)
 
     model.predictions.map(p => p.copy(label = round(p.label))) should be
       (generateWeightedIsotonicInput(Seq(1, 10/6, 10/6, 10/6, 10/6), Seq(-1, 1, -3, 1, -5)))
@@ -147,7 +146,7 @@ class IsotonicRegressionSuite
     val testRDD = sc.parallelize(generateWeightedIsotonicInput(Seq(1, 2, 3, 2, 1), Seq(0, 0, 0, 1, 0))).cache()
 
     val alg = new PoolAdjacentViolators
-    val model = alg.run(testRDD, Isotonic)
+    val model = alg.run(testRDD, true)
 
     model.predictions should be(generateWeightedIsotonicInput(Seq(1, 2, 2, 2, 2), Seq(0, 0, 0, 1, 0)))
   }
@@ -156,7 +155,7 @@ class IsotonicRegressionSuite
     val testRDD = sc.parallelize(generateIsotonicInput(1, 2, 7, 1, 2)).cache()
 
     val alg = new PoolAdjacentViolators
-    val model = alg.run(testRDD, Isotonic)
+    val model = alg.run(testRDD, true)
 
     model.predict(Vectors.dense(0)) should be(1)
     model.predict(Vectors.dense(2)) should be(2)
@@ -168,7 +167,7 @@ class IsotonicRegressionSuite
     val testRDD = sc.parallelize(generateIsotonicInput(7, 5, 3, 5, 1)).cache()
 
     val alg = new PoolAdjacentViolators
-    val model = alg.run(testRDD, Antitonic)
+    val model = alg.run(testRDD, false)
 
     model.predict(Vectors.dense(0)) should be(7)
     model.predict(Vectors.dense(2)) should be(5)
@@ -183,7 +182,7 @@ class IsotonicRegressionSuite
         LabeledPoint(1, Vectors.dense(2)))).cache()
 
     val alg = new PoolAdjacentViolators
-    val model = alg.run(testRDD, Isotonic)
+    val model = alg.run(testRDD, true)
 
     model.predictions should be(generateIsotonicInput(1.5, 1.5))
   }
@@ -201,7 +200,7 @@ class IsotonicRegressionClusterSuite extends FunSuite with LocalClusterSparkCont
 
     // If we serialize data directly in the task closure, the size of the serialized task would be
     // greater than 1MB and hence Spark would throw an error.
-    val model = IsotonicRegression.train(points, Isotonic)
+    val model = IsotonicRegression.train(points, true)
     val predictions = model.predict(points.map(_.features))
   }
 }