move NaN values to the end of the list when sorting

core/src/processing/data/FloatDict.java

@@ -668,7 +668,22 @@ public class FloatDict {
     Sort s = new Sort() {
       @Override
       public int size() {
-        return count;
+        if (useKeys) {
+          return count;  // don't worry about NaN values
+
+        } else {  // first move NaN values to the end of the list
+          int right = count - 1;
+          while (values[right] != values[right]) {
+            right--;
+          }
+          for (int i = right; i >= 0; --i) {
+            if (Float.isNaN(values[i])) {
+              swap(i, right);
+              --right;
+            }
+          }
+          return right + 1;
+        }
       }
 
       @Override

core/src/processing/data/FloatList.java

@@ -566,7 +566,20 @@ public class FloatList implements Iterable<Float> {
     new Sort() {
       @Override
       public int size() {
-        return count;
+        // move NaN values to the end of the list and don't sort them
+        int right = count - 1;
+        while (data[right] != data[right]) {
+          right--;
+        }
+        for (int i = right; i >= 0; --i) {
+          float v = data[i];
+          if (v != v) {
+            data[i] = data[right];
+            data[right] = v;
+            --right;
+          }
+        }
+        return right + 1;
       }
 
       @Override

core/src/processing/data/Sort.java

@@ -31,8 +31,8 @@ public abstract class Sort implements Runnable {
   protected int partition(int left, int right) {
     int pivot = right;
     do {
-      while (compare(++left, pivot) < 0) ;
-      while ((right != 0) && (compare(--right, pivot) > 0)) ;
+      while (compare(++left, pivot) < 0) { }
+      while ((right != 0) && (compare(--right, pivot) > 0)) { }
       swap(left, right);
     } while (left < right);
     swap(left, right);