From 4673e06370ad0c652cd0063f49c44490545919de Mon Sep 17 00:00:00 2001
From: Villu Ruusmann <villu.ruusmann@gmail.com>
Date: Sun, 13 Oct 2024 19:00:47 +0300
Subject: [PATCH] Optimized the evaluation of NormContinuous elements

---
 .../jpmml/evaluator/NormalizationUtil.java    | 30 +++++++++-------
 .../evaluator/NormalizationUtilTest.java      | 35 -------------------
 2 files changed, 17 insertions(+), 48 deletions(-)

diff --git a/pmml-evaluator/src/main/java/org/jpmml/evaluator/NormalizationUtil.java b/pmml-evaluator/src/main/java/org/jpmml/evaluator/NormalizationUtil.java
index f825ce32..3843b4b0 100644
--- a/pmml-evaluator/src/main/java/org/jpmml/evaluator/NormalizationUtil.java
+++ b/pmml-evaluator/src/main/java/org/jpmml/evaluator/NormalizationUtil.java
@@ -58,7 +58,7 @@ public <V extends Number> Value<V> normalize(NormContinuous normContinuous, Valu
 		LinearNorm start;
 		LinearNorm end;
 
-		int index = search(linearNorms, LinearNorm::requireOrig, value);
+		int index = binarySearch(linearNorms, LinearNorm::requireOrig, value);
 		if(index < 0 || index == (linearNorms.size() - 1)){
 			OutlierTreatmentMethod outlierTreatmentMethod = normContinuous.getOutliers();
 
@@ -122,7 +122,7 @@ public <V extends Number> Value<V> denormalize(NormContinuous normContinuous, Va
 		LinearNorm start;
 		LinearNorm end;
 
-		int index = search(linearNorms, LinearNorm::requireNorm, value);
+		int index = binarySearch(linearNorms, LinearNorm::requireNorm, value);
 		if(index < 0 || index == (linearNorms.size() - 1)){
 			throw new NotImplementedException();
 		} else
@@ -136,17 +136,21 @@ public <V extends Number> Value<V> denormalize(NormContinuous normContinuous, Va
 	}
 
 	static
-	<V extends Number> int search(List<LinearNorm> linearNorms, Function<LinearNorm, Number> thresholdFunction, Value<V> value){
+	private <V extends Number> int binarySearch(List<LinearNorm> linearNorms, Function<LinearNorm, Number> thresholdFunction, Value<V> value){
+		int low = 0;
+		int high = linearNorms.size() - 1;
 
-		for(int i = 0, max = linearNorms.size(); i < max; i++){
-			LinearNorm linearNorm = linearNorms.get(i);
+		while(low <= high){
+			int mid = low + (high - low) / 2;
+
+			LinearNorm linearNorm = linearNorms.get(mid);
 
 			Number threshold = thresholdFunction.apply(linearNorm);
 
 			if(value.compareTo(threshold) >= 0){
 
-				if(i < (max - 1)){
-					LinearNorm nextLinearNorm = linearNorms.get(i + 1);
+				if(mid < (linearNorms.size() - 1)){
+					LinearNorm nextLinearNorm = linearNorms.get(mid + 1);
 
 					Number nextThreshold = thresholdFunction.apply(nextLinearNorm);
 
@@ -154,24 +158,24 @@ <V extends Number> int search(List<LinearNorm> linearNorms, Function<LinearNorm,
 					// If the value matches some threshold value exactly,
 					// then it does not matter which bin (ie. this or the next) is used for interpolation.
 					if(value.compareTo(nextThreshold) <= 0){
-						return i;
+						return mid;
 					}
-
-					continue;
 				} else
 
 				// The last element
 				{
-					return i;
+					return mid;
 				}
+
+				low = (mid + 1);
 			} else
 
 			{
-				return -1;
+				high = (mid - 1);
 			}
 		}
 
-		throw new IllegalArgumentException();
+		return -1;
 	}
 
 	static
diff --git a/pmml-evaluator/src/test/java/org/jpmml/evaluator/NormalizationUtilTest.java b/pmml-evaluator/src/test/java/org/jpmml/evaluator/NormalizationUtilTest.java
index 8bff0567..70ddc691 100644
--- a/pmml-evaluator/src/test/java/org/jpmml/evaluator/NormalizationUtilTest.java
+++ b/pmml-evaluator/src/test/java/org/jpmml/evaluator/NormalizationUtilTest.java
@@ -18,9 +18,6 @@
  */
 package org.jpmml.evaluator;
 
-import java.util.ArrayList;
-import java.util.List;
-
 import org.dmg.pmml.LinearNorm;
 import org.dmg.pmml.NormContinuous;
 import org.dmg.pmml.OutlierTreatmentMethod;
@@ -109,33 +106,6 @@ public void standardize(){
 		assertEquals(1d, denormalize(normContinuous, zScore(1d, mu, stdev)), DOUBLE_EXACT);
 	}
 
-	@Test
-	public void search(){
-		List<LinearNorm> linearNorms = new ArrayList<>();
-
-		linearNorms.add(new LinearNorm(0d, null));
-		linearNorms.add(new LinearNorm(1d, null));
-
-		assertEquals(-1, search(linearNorms, -1d));
-		assertEquals(0, search(linearNorms, 0d));
-		assertEquals(0, search(linearNorms, 1d));
-		assertEquals(1, search(linearNorms, 2d));
-
-		linearNorms.add(new LinearNorm(2d, null));
-
-		assertEquals(-1, search(linearNorms, -1d));
-		assertEquals(0, search(linearNorms, 1d));
-		assertEquals(1, search(linearNorms, 2d));
-		assertEquals(2, search(linearNorms, 3d));
-
-		linearNorms.add(new LinearNorm(3d, null));
-
-		assertEquals(-1, search(linearNorms,-1d));
-		assertEquals(1, search(linearNorms, 2d));
-		assertEquals(2, search(linearNorms, 3d));
-		assertEquals(3, search(linearNorms, 4d));
-	}
-
 	static
 	private Double normalize(NormContinuous normContinuous, double value){
 		return (Double)NormalizationUtil.normalize(normContinuous, value);
@@ -146,11 +116,6 @@ private Double denormalize(NormContinuous normContinuous, double value){
 		return (Double)NormalizationUtil.denormalize(normContinuous, value);
 	}
 
-	static
-	private int search(List<LinearNorm> linearNorms, double value){
-		return NormalizationUtil.search(linearNorms, LinearNorm::requireOrig, new DoubleValue(value));
-	}
-
 	static
 	private double interpolate(double x, double[] begin, double[] end){
 		return begin[1] + (x - begin[0]) / (end[0] - begin[0]) * (end[1] - begin[1]);