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