Fixes #24893: added test and run black

Author: mabelvj

pandas/core/reshape/pivot.py

@@ -254,8 +254,9 @@ def _add_margins(
     try:
         for dtype in set(result.dtypes):
             cols = result.select_dtypes([dtype]).columns
-            margin_dummy[cols] = margin_dummy[cols].apply(maybe_downcast_to_dtype,
-                                                          args=(dtype,))
+            margin_dummy[cols] = margin_dummy[cols].apply(
+                maybe_downcast_to_dtype, args=(dtype,)
+            )
         result = result.append(margin_dummy)
     except TypeError:
 

pandas/tests/reshape/test_pivot.py

@@ -1601,7 +1601,6 @@ def test_pivot_table_margins_name_with_aggfunc_list(self):
         expected = pd.DataFrame(table.values, index=ix, columns=cols)
         tm.assert_frame_equal(table, expected)
 
-    @pytest.mark.xfail(reason="GH#17035 (np.mean of ints is casted back to ints)")
     def test_categorical_margins(self, observed):
         # GH 10989
         df = pd.DataFrame(
@@ -1615,6 +1614,24 @@ def test_categorical_margins(self, observed):
         table = df.pivot_table("x", "y", "z", dropna=observed, margins=True)
         tm.assert_frame_equal(table, expected)
 
+    def test_margins_casted_to_float(self):
+        # GH #24893
+        df = pd.DataFrame(
+            {
+                "A": [2, 4, 6, 8],
+                "B": [1, 4, 5, 8],
+                "C": [1, 3, 4, 6],
+                "D": ["X", "X", "Y", "Y"],
+            }
+        )
+
+        result = pd.pivot_table(df, index="D", margins=True)
+        expected = pd.DataFrame(
+            {"A": [3, 7, 5], "B": [2.5, 6.5, 4.5], "C": [2, 5, 3.5]},
+            index=pd.Index(["X", "Y", "All"], name="D"),
+        )
+        tm.assert_frame_equal(result, expected)
+
     @pytest.mark.xfail(reason="GH#17035 (np.mean of ints is casted back to ints)")
     def test_categorical_margins_category(self, observed):
         df = pd.DataFrame(