From b04980a0ce08d09da31415f34e8520209ba0d9c9 Mon Sep 17 00:00:00 2001
From: Matthew Roeschke <10647082+mroeschke@users.noreply.github.com>
Date: Tue, 20 Jun 2023 13:50:02 -0700
Subject: [PATCH 1/2] Backport PR #53651: BUG:
 convert_dtype(dtype_backend=nullable_numpy) with ArrowDtype

---
 doc/source/whatsnew/v2.0.3.rst                     |  1 +
 pandas/core/dtypes/cast.py                         |  5 +++++
 pandas/tests/frame/methods/test_convert_dtypes.py  | 10 +++++++++-
 pandas/tests/series/methods/test_convert_dtypes.py |  8 ++++++++
 4 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/doc/source/whatsnew/v2.0.3.rst b/doc/source/whatsnew/v2.0.3.rst
index 7b6363a094d00..bba149c2b778b 100644
--- a/doc/source/whatsnew/v2.0.3.rst
+++ b/doc/source/whatsnew/v2.0.3.rst
@@ -21,6 +21,7 @@ Fixed regressions
 
 Bug fixes
 ~~~~~~~~~
+- Bug in :func:`DataFrame.convert_dtype` and :func:`Series.convert_dtype` when trying to convert :class:`ArrowDtype` with ``dtype_backend="nullable_numpy"`` (:issue:`53648`)
 - Bug in :func:`RangeIndex.union` when using ``sort=True`` with another :class:`RangeIndex` (:issue:`53490`)
 - Bug in :func:`read_csv` when defining ``dtype`` with ``bool[pyarrow]`` for the ``"c"`` and ``"python"`` engines (:issue:`53390`)
 - Bug in :meth:`Series.str.split` and :meth:`Series.str.rsplit` with ``expand=True`` for :class:`ArrowDtype` with ``pyarrow.string`` (:issue:`53532`)
diff --git a/pandas/core/dtypes/cast.py b/pandas/core/dtypes/cast.py
index 2dbd9465be3c6..9b1aa1a708764 100644
--- a/pandas/core/dtypes/cast.py
+++ b/pandas/core/dtypes/cast.py
@@ -96,6 +96,8 @@
     notna,
 )
 
+from pandas.io._util import _arrow_dtype_mapping
+
 if TYPE_CHECKING:
     from pandas import Index
     from pandas.core.arrays import (
@@ -1147,6 +1149,9 @@ def convert_dtypes(
             pa_type = to_pyarrow_type(base_dtype)
             if pa_type is not None:
                 inferred_dtype = ArrowDtype(pa_type)
+    elif dtype_backend == "numpy_nullable" and isinstance(inferred_dtype, ArrowDtype):
+        # GH 53648
+        inferred_dtype = _arrow_dtype_mapping()[inferred_dtype.pyarrow_dtype]
 
     # error: Incompatible return value type (got "Union[str, Union[dtype[Any],
     # ExtensionDtype]]", expected "Union[dtype[Any], ExtensionDtype]")
diff --git a/pandas/tests/frame/methods/test_convert_dtypes.py b/pandas/tests/frame/methods/test_convert_dtypes.py
index 2adee158379bb..082ef025992dd 100644
--- a/pandas/tests/frame/methods/test_convert_dtypes.py
+++ b/pandas/tests/frame/methods/test_convert_dtypes.py
@@ -146,7 +146,7 @@ def test_pyarrow_engine_lines_false(self):
         with pytest.raises(ValueError, match=msg):
             df.convert_dtypes(dtype_backend="numpy")
 
-    def test_pyarrow_backend_no_convesion(self):
+    def test_pyarrow_backend_no_conversion(self):
         # GH#52872
         pytest.importorskip("pyarrow")
         df = pd.DataFrame({"a": [1, 2], "b": 1.5, "c": True, "d": "x"})
@@ -159,3 +159,11 @@ def test_pyarrow_backend_no_convesion(self):
             dtype_backend="pyarrow",
         )
         tm.assert_frame_equal(result, expected)
+
+    def test_convert_dtypes_pyarrow_to_np_nullable(self):
+        # GH 53648
+        pytest.importorskip("pyarrow")
+        ser = pd.DataFrame(range(2), dtype="int32[pyarrow]")
+        result = ser.convert_dtypes(dtype_backend="numpy_nullable")
+        expected = pd.DataFrame(range(2), dtype="Int32")
+        tm.assert_frame_equal(result, expected)
diff --git a/pandas/tests/series/methods/test_convert_dtypes.py b/pandas/tests/series/methods/test_convert_dtypes.py
index d91cd6a43daea..b0f5093e4951d 100644
--- a/pandas/tests/series/methods/test_convert_dtypes.py
+++ b/pandas/tests/series/methods/test_convert_dtypes.py
@@ -240,3 +240,11 @@ def test_convert_dtype_object_with_na_float(self, infer_objects, dtype):
         result = ser.convert_dtypes(infer_objects=infer_objects)
         expected = pd.Series([1.5, pd.NA], dtype=dtype)
         tm.assert_series_equal(result, expected)
+
+    def test_convert_dtypes_pyarrow_to_np_nullable(self):
+        # GH 53648
+        pytest.importorskip("pyarrow")
+        ser = pd.Series(range(2), dtype="int32[pyarrow]")
+        result = ser.convert_dtypes(dtype_backend="numpy_nullable")
+        expected = pd.Series(range(2), dtype="Int32")
+        tm.assert_series_equal(result, expected)

From 8a868599f5461a5fdc62e9ccad753d0c7d9233c9 Mon Sep 17 00:00:00 2001
From: Matthew Roeschke <10647082+mroeschke@users.noreply.github.com>
Date: Tue, 20 Jun 2023 15:16:44 -0700
Subject: [PATCH 2/2] Move import

---
 pandas/core/dtypes/cast.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/pandas/core/dtypes/cast.py b/pandas/core/dtypes/cast.py
index 9b1aa1a708764..aef8d483a902f 100644
--- a/pandas/core/dtypes/cast.py
+++ b/pandas/core/dtypes/cast.py
@@ -1039,6 +1039,8 @@ def convert_dtypes(
     """
     inferred_dtype: str | DtypeObj
 
+    from pandas.core.arrays.arrow.dtype import ArrowDtype
+
     if (
         convert_string or convert_integer or convert_boolean or convert_floating
     ) and isinstance(input_array, np.ndarray):
@@ -1121,7 +1123,6 @@ def convert_dtypes(
 
     if dtype_backend == "pyarrow":
         from pandas.core.arrays.arrow.array import to_pyarrow_type
-        from pandas.core.arrays.arrow.dtype import ArrowDtype
         from pandas.core.arrays.string_ import StringDtype
 
         assert not isinstance(inferred_dtype, str)