From 50c453b30e2cd094010380d63816775ae7db7a2a Mon Sep 17 00:00:00 2001
From: Patrick Hoefler <61934744+phofl@users.noreply.github.com>
Date: Sun, 3 Sep 2023 16:57:05 +0200
Subject: [PATCH 1/3] BUG: pct_change showing unnecessary FutureWarning

---
 doc/source/whatsnew/v2.1.1.rst                 | 1 +
 pandas/core/generic.py                         | 4 +++-
 pandas/tests/series/methods/test_pct_change.py | 8 ++++++++
 3 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/doc/source/whatsnew/v2.1.1.rst b/doc/source/whatsnew/v2.1.1.rst
index a6848dad6e3cd..3534a275122c0 100644
--- a/doc/source/whatsnew/v2.1.1.rst
+++ b/doc/source/whatsnew/v2.1.1.rst
@@ -29,6 +29,7 @@ Fixed regressions
 Bug fixes
 ~~~~~~~~~
 - Fixed bug in :meth:`DataFrame.stack` with ``future_stack=True`` and columns a non-:class:`MultiIndex` consisting of tuples (:issue:`54948`)
+- Fixed bug in :meth:`Series.pct_change` and :meth:`DataFrame.pct_change` showing unnecessary ``FutureWarning`` (:issue:`54981`)
 
 .. ---------------------------------------------------------------------------
 .. _whatsnew_211.other:
diff --git a/pandas/core/generic.py b/pandas/core/generic.py
index b9407ebe6624a..83f3ac3ed042e 100644
--- a/pandas/core/generic.py
+++ b/pandas/core/generic.py
@@ -11709,7 +11709,9 @@ def pct_change(
                 stacklevel=find_stack_level(),
             )
         if fill_method is lib.no_default:
-            if self.isna().values.any():
+            mask = self.isna().values
+            mask = mask[np.argmax(~mask) :]
+            if mask.any():
                 warnings.warn(
                     "The default fill_method='pad' in "
                     f"{type(self).__name__}.pct_change is deprecated and will be "
diff --git a/pandas/tests/series/methods/test_pct_change.py b/pandas/tests/series/methods/test_pct_change.py
index 4dabf7b87e2cd..6740b8756853e 100644
--- a/pandas/tests/series/methods/test_pct_change.py
+++ b/pandas/tests/series/methods/test_pct_change.py
@@ -107,3 +107,11 @@ def test_pct_change_with_duplicated_indices(fill_method):
 
     expected = Series([np.nan, np.nan, 1.0, 0.5, 2.0, 1.0], index=["a", "b"] * 3)
     tm.assert_series_equal(result, expected)
+
+
+def test_pct_change_no_warning_na_beginning():
+    # GH#54981
+    ser = Series([None, None, 1, 2, 3])
+    result = ser.pct_change()
+    expected = Series([np.nan, np.nan, np.nan, 1, 0.5])
+    tm.assert_series_equal(result, expected)

From b976afdcae4acedc92dcbd9f566859d3f2ec9aa4 Mon Sep 17 00:00:00 2001
From: Patrick Hoefler <patrick_hoefler@gmx.net>
Date: Tue, 5 Sep 2023 14:30:33 +0200
Subject: [PATCH 2/3] Fix df case

---
 pandas/core/generic.py                        | 25 +++++++++++--------
 pandas/tests/frame/methods/test_pct_change.py | 18 +++++++++++++
 2 files changed, 32 insertions(+), 11 deletions(-)

diff --git a/pandas/core/generic.py b/pandas/core/generic.py
index 83f3ac3ed042e..0bf925ceee2d1 100644
--- a/pandas/core/generic.py
+++ b/pandas/core/generic.py
@@ -11709,17 +11709,20 @@ def pct_change(
                 stacklevel=find_stack_level(),
             )
         if fill_method is lib.no_default:
-            mask = self.isna().values
-            mask = mask[np.argmax(~mask) :]
-            if mask.any():
-                warnings.warn(
-                    "The default fill_method='pad' in "
-                    f"{type(self).__name__}.pct_change is deprecated and will be "
-                    "removed in a future version. Call ffill before calling "
-                    "pct_change to retain current behavior and silence this warning.",
-                    FutureWarning,
-                    stacklevel=find_stack_level(),
-                )
+            for _, col in self.items():
+                mask = col.isna().values
+                mask = mask[np.argmax(~mask) :]
+                if mask.any():
+                    warnings.warn(
+                        "The default fill_method='pad' in "
+                        f"{type(self).__name__}.pct_change is deprecated and will be "
+                        "removed in a future version. Call ffill before calling "
+                        "pct_change to retain current behavior and silence this "
+                        "warning.",
+                        FutureWarning,
+                        stacklevel=find_stack_level(),
+                    )
+                    break
             fill_method = "pad"
         if limit is lib.no_default:
             limit = None
diff --git a/pandas/tests/frame/methods/test_pct_change.py b/pandas/tests/frame/methods/test_pct_change.py
index d0153da038a75..ede212ae18ae9 100644
--- a/pandas/tests/frame/methods/test_pct_change.py
+++ b/pandas/tests/frame/methods/test_pct_change.py
@@ -160,3 +160,21 @@ def test_pct_change_with_duplicated_indices(fill_method):
         index=["a", "b"] * 3,
     )
     tm.assert_frame_equal(result, expected)
+
+
+def test_pct_change_none_beginning_no_warning():
+    # GH#54481
+    df = DataFrame(
+        [
+            [1, None],
+            [2, 1],
+            [3, 2],
+            [4, 3],
+            [5, 4],
+        ]
+    )
+    result = df.pct_change()
+    expected = DataFrame(
+        {0: [np.nan, 1, 0.5, 1 / 3, 0.25], 1: [np.nan, np.nan, 1, 0.5, 1 / 3]}
+    )
+    tm.assert_frame_equal(result, expected)

From e353fc98ea0cc8323d6ce9775dfd7325cffa4e56 Mon Sep 17 00:00:00 2001
From: Patrick Hoefler <patrick_hoefler@gmx.net>
Date: Wed, 6 Sep 2023 22:12:40 +0200
Subject: [PATCH 3/3] Fix

---
 pandas/core/generic.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/pandas/core/generic.py b/pandas/core/generic.py
index 52a6f243609a5..fb3549be96ec1 100644
--- a/pandas/core/generic.py
+++ b/pandas/core/generic.py
@@ -11793,7 +11793,8 @@ def pct_change(
                 stacklevel=find_stack_level(),
             )
         if fill_method is lib.no_default:
-            for _, col in self.items():
+            cols = self.items() if self.ndim == 2 else [(None, self)]
+            for _, col in cols:
                 mask = col.isna().values
                 mask = mask[np.argmax(~mask) :]
                 if mask.any():