Solve bug. Large dataset produced a negative AUC or an AUC bigger than 1

src/main/java/be/cylab/java/roc/Main.java

@@ -32,12 +32,12 @@ public final class Main {
         System.out.println("PR AUC with trapezoid : " + pr.computePRAUC());
         pr.computePrcPointsAndGenerateCurve("PR_curve.png");
 
-        double[] long_data = new double[200000];
+        double[] long_data = new double[250000];
         double[] long_alert = new double[long_data.length];
         for (int i = 0; i < long_data.length; i++) {
             long_data[i] = Math.random();
             double trig = Math.random();
-            if (trig < 0.2) {
+            if (trig < 0.5) {
                 long_alert[i] = 0.0;
             } else {
                 long_alert[i] = 1.0;

src/main/java/be/cylab/java/roc/Roc.java

@@ -16,8 +16,8 @@ import java.util.List;
 public class Roc {
 
     private List<Point> points;
-    private int positive_examples_number;
-    private int negative_examples_number;
+    private double positive_examples_number;
+    private double negative_examples_number;
 
     /**
      * Constructor of ROC object.

src/test/java/be/cylab/java/roc/RocTest.java

@@ -48,4 +48,21 @@ class RocTest {
         Roc roc = new Roc("src/main/resources/RocSampleData.csv");
         assertEquals(auc, roc.computeAUC(), 0.00000001);
     }
+    @Test
+    void computeAUCWithBigDataset() {
+        double[] long_data = new double[200000];
+        double[] long_alert = new double[long_data.length];
+        for (int i = 0; i < long_data.length; i++) {
+            long_data[i] = Math.random();
+            double trig = Math.random();
+            if (trig < 0.5) {
+                long_alert[i] = 0.0;
+            } else {
+                long_alert[i] = 1.0;
+            }
+        }
+        Roc long_roc = new Roc(long_data, long_alert);
+        assertTrue(long_roc.computeAUC() < 1.0 && long_roc.computeAUC() > 0.0);
+
+    }
 }
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