From d62e1b9b5b4826afdc178c892fb7b31691236874 Mon Sep 17 00:00:00 2001
From: Prabakaran Kumaresshan <k_prabakaran@hotmail.com>
Date: Sat, 5 Jan 2019 09:15:59 +0530
Subject: [PATCH] DOC: update applymap docstring in pandas/core/frame.py
 (#24612)

---
 pandas/core/frame.py | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/pandas/core/frame.py b/pandas/core/frame.py
index a50def7357826..9c9720522189d 100644
--- a/pandas/core/frame.py
+++ b/pandas/core/frame.py
@@ -6501,6 +6501,14 @@ def applymap(self, func):
         --------
         DataFrame.apply : Apply a function along input axis of DataFrame.
 
+        Notes
+        -----
+        In the current implementation applymap calls `func` twice on the
+        first column/row to decide whether it can take a fast or slow
+        code path. This can lead to unexpected behavior if `func` has
+        side-effects, as they will take effect twice for the first
+        column/row.
+
         Examples
         --------
         >>> df = pd.DataFrame([[1, 2.12], [3.356, 4.567]])