commit dea908b0b601bdeea98765eeea2643e225a42bf4
author aherbert <aherbert@apache.org> Wed Jul 21 14:59:43 2021 +0100
committer aherbert <aherbert@apache.org> Wed Jul 21 14:59:43 2021 +0100
tree 1bd5a9ca021dfba12df0a97244543266fd8f2776
parent 91ab0425cc7b8268918a630b787b572528ce7ec4

Use binary search for the quartile

This reduces the comparisons to 2 for all points. Previous algorithm
had:

25% - 1
25% - 2
50% - 3

Mean = 2.25

commons-statistics-distribution/src/test/java/org/apache/commons/statistics/distribution/TestUtils.java

diff --git a/commons-statistics-distribution/src/test/java/org/apache/commons/statistics/distribution/TestUtils.java b/commons-statistics-distribution/src/test/java/org/apache/commons/statistics/distribution/TestUtils.java
index 717cdad..df770ee 100644
--- a/commons-statistics-distribution/src/test/java/org/apache/commons/statistics/distribution/TestUtils.java
+++ b/commons-statistics-distribution/src/test/java/org/apache/commons/statistics/distribution/TestUtils.java
@@ -230,14 +230,10 @@
      * @param quartiles Quartiles.
      */
     public static void updateCounts(double value, long[] counts, double[] quartiles) {
-        if (value < quartiles[0]) {
-            counts[0]++;
-        } else if (value > quartiles[2]) {
-            counts[3]++;
-        } else if (value > quartiles[1]) {
-            counts[2]++;
+        if (value > quartiles[1]) {
+            counts[value <= quartiles[2] ? 2 : 3]++;
         } else {
-            counts[1]++;
+            counts[value <= quartiles[0] ? 0 : 1]++;
         }
     }