Fix df case

phofl · Sep 5, 2023 · b976afd · b976afd
1 parent 50c453b
commit b976afd
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Showing 2 changed files with 32 additions and 11 deletions.
diff --git 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
@@ -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)