Return view for xs when droplevel=False with regular Index (#37832)

Author: phofl

pandas/core/generic.py

@@ -3759,7 +3759,7 @@ class   animal   locomotion
                 dtype=new_values.dtype,
             )
         elif is_scalar(loc):
-            result = self.iloc[:, [loc]]
+            result = self.iloc[:, slice(loc, loc + 1)]
         elif axis == 1:
             result = self.iloc[:, loc]
         else:

pandas/tests/frame/indexing/test_xs.py

@@ -319,3 +319,11 @@ def test_xs_droplevel_false(self):
         result = df.xs("a", axis=1, drop_level=False)
         expected = DataFrame({"a": [1]})
         tm.assert_frame_equal(result, expected)
+
+    def test_xs_droplevel_false_view(self):
+        # GH#37832
+        df = DataFrame([[1, 2, 3]], columns=Index(["a", "b", "c"]))
+        result = df.xs("a", axis=1, drop_level=False)
+        df.values[0, 0] = 2
+        expected = DataFrame({"a": [2]})
+        tm.assert_frame_equal(result, expected)