From 38a347e5f08349c636010b177e6e12a97ace0c25 Mon Sep 17 00:00:00 2001
From: Mikko Kouhia <mikko.kouhia@iki.fi>
Date: Sun, 1 May 2022 12:38:02 +0300
Subject: [PATCH] Return indices also if population is empty

---
 pymoo/core/duplicate.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pymoo/core/duplicate.py b/pymoo/core/duplicate.py
index 0606e91db..172f66195 100644
--- a/pymoo/core/duplicate.py
+++ b/pymoo/core/duplicate.py
@@ -20,7 +20,7 @@ def do(self, pop, *args, return_indices=False, to_itself=True):
         original = pop
 
         if len(pop) == 0:
-            return pop
+            return (pop, [], []) if return_indices else pop
 
         if to_itself:
             pop = pop[~self._do(pop, None, np.full(len(pop), False))]