From f6275e04bd71d8aad78043b370914ccb7aea11d9 Mon Sep 17 00:00:00 2001
From: Philipp Rudiger <prudiger@anaconda.com>
Date: Mon, 25 May 2020 14:00:19 +0200
Subject: [PATCH] Do not apply empty apply (#465)

---
 hvplot/util.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/hvplot/util.py b/hvplot/util.py
index d83417893..2eef9a1bf 100644
--- a/hvplot/util.py
+++ b/hvplot/util.py
@@ -399,7 +399,8 @@ def process_derived_datetime_pandas(data, not_found, indexes=None):
                 index = data.axes[indexes.index(base_col)]
                 if isdate(index):
                     extra_cols[var] = getattr(index, dt_str)
-    data = data.assign(**extra_cols)
+    if extra_cols:
+        data = data.assign(**extra_cols)
     not_found = [var for var in not_found if var not in extra_cols.keys()]
 
     return not_found, data