WARN: sort_values for midx warns unnecessarily if nan is in level (#5…

…5386)
pandas-dev · Oct 4, 2023 · 6a8055d · 6a8055d
1 parent eb6317a
commit 6a8055d
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diff --git a/pandas/core/indexes/multi.py b/pandas/core/indexes/multi.py
@@ -1948,7 +1948,7 @@ def _sort_levels_monotonic(self, raise_if_incomparable: bool = False) -> MultiIn
                     # indexer to reorder the level codes
                     indexer = ensure_platform_int(indexer)
                     ri = lib.get_reverse_indexer(indexer, len(indexer))
-                    level_codes = algos.take_nd(ri, level_codes)
+                    level_codes = algos.take_nd(ri, level_codes, fill_value=-1)
 
             new_levels.append(lev)
             new_codes.append(level_codes)

diff --git a/pandas/tests/indexes/multi/test_sorting.py b/pandas/tests/indexes/multi/test_sorting.py
@@ -338,3 +338,12 @@ def test_sort_values_with_na_na_position(dtype, na_position):
         ]
     expected = MultiIndex.from_arrays(arrays)
     tm.assert_index_equal(result, expected)
+
+
+def test_sort_unnecessary_warning():
+    # GH#55386
+    midx = MultiIndex.from_tuples([(1.5, 2), (3.5, 3), (0, 1)])
+    midx = midx.set_levels([2.5, np.nan, 1], level=0)
+    result = midx.sort_values()
+    expected = MultiIndex.from_tuples([(1, 3), (2.5, 1), (np.nan, 2)])
+    tm.assert_index_equal(result, expected)