BUG: pivot_table with margins and numeric columns (pandas-dev#55933)

* fix and add test

* add whatsnew

* rm comment

Author: quangngd

doc/source/whatsnew/v2.2.0.rst

@@ -466,6 +466,7 @@ Reshaping
 - Bug in :func:`merge` returning columns in incorrect order when left and/or right is empty (:issue:`51929`)
 - Bug in :meth:`pandas.DataFrame.melt` where an exception was raised if ``var_name`` was not a string (:issue:`55948`)
 - Bug in :meth:`pandas.DataFrame.melt` where it would not preserve the datetime (:issue:`55254`)
+- Bug in :meth:`pandas.DataFrame.pivot_table` where the row margin is incorrect when the columns have numeric names (:issue:`26568`)
 
 Sparse
 ^^^^^^

pandas/core/reshape/pivot.py

@@ -421,9 +421,10 @@ def _all_key(key):
         row_margin = data[cols + values].groupby(cols, observed=observed).agg(aggfunc)
         row_margin = row_margin.stack(future_stack=True)
 
-        # slight hack
-        new_order = [len(cols)] + list(range(len(cols)))
-        row_margin.index = row_margin.index.reorder_levels(new_order)
+        # GH#26568. Use names instead of indices in case of numeric names
+        new_order_indices = [len(cols)] + list(range(len(cols)))
+        new_order_names = [row_margin.index.names[i] for i in new_order_indices]
+        row_margin.index = row_margin.index.reorder_levels(new_order_names)
     else:
         row_margin = data._constructor_sliced(np.nan, index=result.columns)
 

pandas/tests/reshape/test_pivot.py

@@ -2666,3 +2666,18 @@ def test_pivot_table_handles_explicit_datetime_types(self):
             names=["a", "date"],
         )
         tm.assert_index_equal(pivot.index, expected)
+
+    def test_pivot_table_with_margins_and_numeric_column_names(self):
+        # GH#26568
+        df = DataFrame([["a", "x", 1], ["a", "y", 2], ["b", "y", 3], ["b", "z", 4]])
+
+        result = df.pivot_table(
+            index=0, columns=1, values=2, aggfunc="sum", fill_value=0, margins=True
+        )
+
+        expected = DataFrame(
+            [[1, 2, 0, 3], [0, 3, 4, 7], [1, 5, 4, 10]],
+            columns=Index(["x", "y", "z", "All"], name=1),
+            index=Index(["a", "b", "All"], name=0),
+        )
+        tm.assert_frame_equal(result, expected)