Fix convert_dtype complex

Author: Ma-gi-cian

pandas/core/dtypes/cast.py

@@ -934,6 +934,10 @@ def convert_dtypes(
     if (
         convert_string or convert_integer or convert_boolean or convert_floating
     ) and isinstance(input_array, np.ndarray):
+
+        if input_array.dtype.kind == 'c':
+            return input_array.dtype
+
         if input_array.dtype == object:
             inferred_dtype = lib.infer_dtype(input_array)
         else:
@@ -954,7 +958,7 @@ def convert_dtypes(
                 inferred_dtype = NUMPY_INT_TO_DTYPE.get(
                     input_array.dtype, target_int_dtype
                 )
-            elif input_array.dtype.kind in "fcb":
+            elif input_array.dtype.kind in "fb":
                 # TODO: de-dup with maybe_cast_to_integer_array?
                 arr = input_array[notna(input_array)]
                 if len(arr) < len(input_array) and not is_nan_na():
@@ -972,7 +976,7 @@ def convert_dtypes(
                 inferred_dtype = target_int_dtype
 
         if convert_floating:
-            if input_array.dtype.kind in "fcb":
+            if input_array.dtype.kind in "fb":
                 # i.e. numeric but not integer
                 from pandas.core.arrays.floating import NUMPY_FLOAT_TO_DTYPE
 
@@ -1028,11 +1032,11 @@ def convert_dtypes(
 
         if (
             (convert_integer and inferred_dtype.kind in "iu")
-            or (convert_floating and inferred_dtype.kind in "fc")
+            or (convert_floating and inferred_dtype.kind in "f")
             or (convert_boolean and inferred_dtype.kind == "b")
             or (convert_string and isinstance(inferred_dtype, StringDtype))
             or (
-                inferred_dtype.kind not in "iufcb"
+                inferred_dtype.kind not in "iufb"
                 and not isinstance(inferred_dtype, StringDtype)
                 and not isinstance(inferred_dtype, CategoricalDtype)
             )

pandas/tests/frame/methods/test_convert_dtypes.py

@@ -228,3 +228,10 @@ def test_convert_dtype_pyarrow_timezone_preserve(self):
         result = df.convert_dtypes(dtype_backend="pyarrow")
         expected = df.copy()
         tm.assert_frame_equal(result, expected)
+
+    def test_convert_dtypes_complex(self):
+        # GH 60129
+        df = pd.DataFrame({'a': [1.0+5.0j, 1.5-3.0j]})
+        result = df.convert_dtypes()
+        tm.assert_frame_equal(result, df)
+        assert result['a'].dtype.kind == 'c'

pandas/tests/series/methods/test_convert_dtypes.py

@@ -332,3 +332,10 @@ def test_convert_dtype_pyarrow_timezone_preserve(self):
         result = ser.convert_dtypes(dtype_backend="pyarrow")
         expected = ser.copy()
         tm.assert_series_equal(result, expected)
+
+    def test_convert_dtypes_complex(self):
+        # GH 60129
+        ser = pd.Series([1.5+3.0j, 1.5-3.0j])
+        result = ser.convert_dtypes()
+        tm.assert_series_equal(result, ser)
+        assert result.dtype.kind == 'c'