Correct statistics with an infinite value

aherbert · Sep 20, 2023 · fd485f5 · fd485f5
1 parent 622ebc7
commit fd485f5
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Showing 2 changed files with 11 additions and 2 deletions.
diff --git a/gdsc-core/src/main/java/uk/ac/sussex/gdsc/core/utils/Statistics.java b/gdsc-core/src/main/java/uk/ac/sussex/gdsc/core/utils/Statistics.java
@@ -407,7 +407,7 @@ public double getStandardDeviation() {
     if (stdDev > 0) {
       stdDev = Math.sqrt(stdDev / (size - 1));
     } else {
-      stdDev = 0.0;
+      stdDev = Double.isFinite(stdDev) ? 0.0 : Double.NaN;
     }
     return stdDev;
   }
@@ -428,7 +428,7 @@ public double getVariance() {
     if (variance > 0) {
       variance = variance / (size - 1);
     } else {
-      variance = 0.0;
+      variance = Double.isFinite(variance) ? 0.0 : Double.NaN;
     }
     return variance;
   }

diff --git a/gdsc-core/src/test/java/uk/ac/sussex/gdsc/core/utils/StatisticsTest.java b/gdsc-core/src/test/java/uk/ac/sussex/gdsc/core/utils/StatisticsTest.java
@@ -383,4 +383,13 @@ void testConfidenceInterval() {
     Assertions.assertTrue(intervals[1] > intervals[0]);
     Assertions.assertTrue(intervals[2] > intervals[1]);
   }
+
+  @Test
+  void testStdDevVarianceWithInfiniteValues() {
+    final Statistics stats = new Statistics();
+    stats.add(Double.POSITIVE_INFINITY);
+    Assertions.assertEquals(Double.NaN, stats.getStandardError());
+    Assertions.assertEquals(Double.NaN, stats.getStandardDeviation());
+    Assertions.assertEquals(Double.NaN, stats.getVariance());
+  }
 }