BUG: Multiindex.equals not commutative for ea dtype

Author: phofl

doc/source/whatsnew/v1.5.0.rst

@@ -347,7 +347,7 @@ Missing
 
 MultiIndex
 ^^^^^^^^^^
--
+- Bug in :class:`MultiIndex.equals` not commutative when only one side has extension array dtype (:issue:`46026`)
 -
 
 I/O

pandas/core/indexes/multi.py

@@ -3224,8 +3224,8 @@ def convert_indexer(start, stop, step, indexer=indexer, codes=level_codes):
                 return convert_indexer(start, stop + 1, step)
             else:
                 # sorted, so can return slice object -> view
-                i = algos.searchsorted(level_codes, start, side="left")
-                j = algos.searchsorted(level_codes, stop, side="right")
+                i = level_codes.searchsorted(start, side="left")
+                j = level_codes.searchsorted(stop, side="right")
                 return slice(i, j, step)
 
         else:
@@ -3248,12 +3248,12 @@ def convert_indexer(start, stop, step, indexer=indexer, codes=level_codes):
 
             if isinstance(idx, slice):
                 # e.g. test_partial_string_timestamp_multiindex
-                start = algos.searchsorted(level_codes, idx.start, side="left")
+                start = level_codes.searchsorted(idx.start, side="left")
                 # NB: "left" here bc of slice semantics
-                end = algos.searchsorted(level_codes, idx.stop, side="left")
+                end = level_codes.searchsorted(idx.stop, side="left")
             else:
-                start = algos.searchsorted(level_codes, idx, side="left")
-                end = algos.searchsorted(level_codes, idx, side="right")
+                start = level_codes.searchsorted(idx, side="left")
+                end = level_codes.searchsorted(idx, side="right")
 
             if start == end:
                 # The label is present in self.levels[level] but unused:
@@ -3304,10 +3304,10 @@ def get_locs(self, seq):
             )
 
         n = len(self)
-        # indexer is the list of all positions that we want to take; it
-        #  is created on the first entry in seq and narrowed down as we
-        #  look at remaining entries
-        indexer = None
+        # indexer is the list of all positions that we want to take; we
+        #  start with it being everything and narrow it down as we look at each
+        #  entry in `seq`
+        indexer = Index(np.arange(n))
 
         if any(x is Ellipsis for x in seq):
             raise NotImplementedError(
@@ -3330,9 +3330,7 @@ def _convert_to_indexer(r) -> Int64Index:
                 r = r.nonzero()[0]
             return Int64Index(r)
 
-        def _update_indexer(idxr: Index, indexer: Index | None) -> Index:
-            if indexer is None:
-                return idxr
+        def _update_indexer(idxr: Index, indexer: Index) -> Index:
             indexer_intersection = indexer.intersection(idxr)
             if indexer_intersection.empty and not idxr.empty and not indexer.empty:
                 raise KeyError(seq)
@@ -3417,8 +3415,7 @@ def _update_indexer(idxr: Index, indexer: Index | None) -> Index:
 
             elif com.is_null_slice(k):
                 # empty slice
-                if indexer is None:
-                    indexer = Index(np.arange(n))
+                pass
 
             elif isinstance(k, slice):
 
@@ -3611,6 +3608,10 @@ def equals(self, other: object) -> bool:
                 # i.e. ExtensionArray
                 if not self_values.equals(other_values):
                     return False
+            elif not isinstance(other_values, np.ndarray):
+                # i.e. other is ExtensionArray
+                if not other_values.equals(self_values):
+                    return False
             else:
                 if not array_equivalent(self_values, other_values):
                     return False

pandas/tests/indexes/multi/test_equivalence.py

@@ -288,3 +288,11 @@ def test_multiindex_compare():
     expected = Series([False, False])
     result = Series(midx > midx)
     tm.assert_series_equal(result, expected)
+
+
+def test_equals_ea_int_regular_int():
+    # GH#46026
+    mi1 = MultiIndex.from_arrays([Index([1, 2], dtype="Int64"), [3, 4]])
+    mi2 = MultiIndex.from_arrays([[1, 2], [3, 4]])
+    assert not mi1.equals(mi2)
+    assert not mi2.equals(mi1)