Fix pandas-dev#60766:.map,.apply would convert element type for extension array.

Author: pedromfdiogo

pandas/core/arrays/masked.py

@@ -1325,7 +1325,7 @@ def max(self, *, skipna: bool = True, axis: AxisInt | None = 0, **kwargs):
         return self._wrap_reduction_result("max", result, skipna=skipna, axis=axis)
 
     def map(self, mapper, na_action: Literal["ignore"] | None = None):
-        return map_array(self.to_numpy(), mapper, na_action=na_action)
+        return map_array(self, mapper, na_action=na_action)
 
     @overload
     def any(

pandas/tests/arrays/masked/test_basemaskedarray_map.py

@@ -0,0 +1,18 @@
+import pandas as pd
+
+def test_basemaskedarray_map():
+    for dtype, data, expected_data in [
+        ("Int32", [1, 2, None, 4], [2, 3, pd.NA, 5]),  
+          
+    ]:
+        s = pd.Series(data, dtype=dtype)
+
+        def transform(x):
+            if x is None:  
+                return x
+            return x + 1
+
+        result = s.map(transform)
+        expected = pd.Series(expected_data, dtype=result.dtype) 
+
+        assert result.tolist() == expected.tolist()