Repository: pandas-dev/pandas (python)

Issue:
DOC: DataFrame.unstack should accept fill_value with more types than just int/str/dict
### Pandas version checks

- [x] I have checked that the issue still exists on the latest versions of the docs on `main` [here](https://pandas.pydata.org/docs/dev/)


### Location of the documentation

https://pandas.pydata.org/docs/dev/reference/api/pandas.DataFrame.unstack.html#pandas.DataFrame.unstack

### Documentation problem

Currently the docs stipulate that only `int`, `str` and `dict` are allowed for the `fill_value`, yet it seems like all the types that could be used when creating a `DataFrame` seem to pass at runtime. I have not tried them all yet but int, float, complex, timestamp are working fine.

### Suggested fix for documentation

Add all allowed types for dataframe elements for the `fill_value` field.
Happy to create the PR if this is agreed by the maintainers. I will raise the issue in the pandas-stubs repo.

Pull request:
DOC: change `pandas.DataFrame.unstack`'s `fill_value` param to scalar
- [x] closes #61445 (Replace xxxx with the GitHub issue number)
- [x] [Tests added and passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#writing-tests) if fixing a bug or adding a new feature
- [x] All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).
- [x] Added [type annotations](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#type-hints) to new arguments/methods/functions.
- [x] Added an entry in the latest `doc/source/whatsnew/vX.X.X.rst` file if fixing a bug or adding a new feature.

<img width="796" alt="image" src="https://github.com/user-attachments/assets/2540c012-dc39-47bd-81f9-263855a2c69d" />


Patch:
diff --git a/doc/source/whatsnew/v2.3.0.rst b/doc/source/whatsnew/v2.3.0.rst
index ac74e6a8e5..65bd941800 100644
--- a/doc/source/whatsnew/v2.3.0.rst
+++ b/doc/source/whatsnew/v2.3.0.rst
@@ -50,10 +50,20 @@ Notable bug fixes
 
 These are bug fixes that might have notable behavior changes.
 
-.. _whatsnew_230.notable_bug_fixes.notable_bug_fix1:
+.. _whatsnew_230.notable_bug_fixes.string_comparisons:
 
-notable_bug_fix1
-^^^^^^^^^^^^^^^^
+Comparisons between different string dtypes
+^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+In previous versions, comparing Series of different string dtypes (e.g. ``pd.StringDtype("pyarrow", na_value=pd.NA)`` against ``pd.StringDtype("python", na_value=np.nan)``) would result in inconsistent resulting dtype or incorrectly raise. pandas will now use the hierarchy
+
+    object < (python, NaN) < (pyarrow, NaN) < (python, NA) < (pyarrow, NA)
+
+in determining the result dtype when there are different string dtypes compared. Some examples:
+
+- When ``pd.StringDtype("pyarrow", na_value=pd.NA)`` is compared against any other string dtype, the result will always be ``boolean[pyarrow]``.
+- When ``pd.StringDtype("python", na_value=pd.NA)`` is compared against ``pd.StringDtype("pyarrow", na_value=np.nan)``, the result will be ``boolean``, the NumPy-backed nullable extension array.
+- When ``pd.StringDtype("python", na_value=pd.NA)`` is compared against ``pd.StringDtype("python", na_value=np.nan)``, the result will be ``boolean``, the NumPy-backed nullable extension array.
 
 .. _whatsnew_230.api_changes:
 
diff --git a/doc/source/whatsnew/v3.0.0.rst b/doc/source/whatsnew/v3.0.0.rst
index 6642f5855f..79b304e797 100644
--- a/doc/source/whatsnew/v3.0.0.rst
+++ b/doc/source/whatsnew/v3.0.0.rst
@@ -904,6 +904,7 @@ Other
 - Bug in ``Series.list`` methods not preserving the original name. (:issue:`60522`)
 - Bug in printing a :class:`DataFrame` with a :class:`DataFrame` stored in :attr:`DataFrame.attrs` raised a ``ValueError`` (:issue:`60455`)
 - Bug in printing a :class:`Series` with a :class:`DataFrame` stored in :attr:`Series.attrs` raised a ``ValueError`` (:issue:`60568`)
+- Fixed bug where the :class:`DataFrame` constructor misclassified array-like objects with a ``.name`` attribute as :class:`Series` or :class:`Index` (:issue:`61443`)
 - Fixed regression in :meth:`DataFrame.from_records` not initializing subclasses properly (:issue:`57008`)
 
 .. ***DO NOT USE THIS SECTION***
diff --git a/pandas/core/arrays/arrow/array.py b/pandas/core/arrays/arrow/array.py
index d7187b57a6..0b90bcea35 100644
--- a/pandas/core/arrays/arrow/array.py
+++ b/pandas/core/arrays/arrow/array.py
@@ -33,7 +33,6 @@ from pandas.core.dtypes.cast import (
     infer_dtype_from_scalar,
 )
 from pandas.core.dtypes.common import (
-    CategoricalDtype,
     is_array_like,
     is_bool_dtype,
     is_float_dtype,
@@ -730,9 +729,7 @@ class ArrowExtensionArray(
 
     def _cmp_method(self, other, op) -> ArrowExtensionArray:
         pc_func = ARROW_CMP_FUNCS[op.__name__]
-        if isinstance(
-            other, (ArrowExtensionArray, np.ndarray, list, BaseMaskedArray)
-        ) or isinstance(getattr(other, "dtype", None), CategoricalDtype):
+        if isinstance(other, (ExtensionArray, np.ndarray, list)):
             try:
                 result = pc_func(self._pa_array, self._box_pa(other))
             except pa.ArrowNotImplementedError:
diff --git a/pandas/core/arrays/string_.py b/pandas/core/arrays/string_.py
index ac758d0ef0..8048306df9 100644
--- a/pandas/core/arrays/string_.py
+++ b/pandas/core/arrays/string_.py
@@ -1015,7 +1015,30 @@ class StringArray(BaseStringArray, NumpyExtensionArray):  # type: ignore[misc]
         return super().searchsorted(value=value, side=side, sorter=sorter)
 
     def _cmp_method(self, other, op):
-        from pandas.arrays import BooleanArray
+        from pandas.arrays import (
+            ArrowExtensionArray,
+            BooleanArray,
+        )
+
+        if (
+            isinstance(other, BaseStringArray)
+            and self.dtype.na_value is not libmissing.NA
+            and other.dtype.na_value is libmissing.NA
+        ):
+            # NA has priority of NaN semantics
+            return NotImplemented
+
+        if isinstance(other, ArrowExtensionArray):
+            if isinstance(other, BaseStringArray):
+                # pyarrow storage has priority over python storage
+                # (except if we have NA semantics and other not)
+                if not (
+                    self.dtype.na_value is libmissing.NA
+                    and other.dtype.na_value is not libmissing.NA
+                ):
+                    return NotImplemented
+            else:
+                return NotImplemented
 
         if isinstance(other, StringArray):
             other = other._ndarray
diff --git a/pandas/core/arrays/string_arrow.py b/pandas/core/arrays/string_arrow.py
index a39d64429d..9668981df8 100644
--- a/pandas/core/arrays/string_arrow.py
+++ b/pandas/core/arrays/string_arrow.py
@@ -473,6 +473,14 @@ class ArrowStringArray(ObjectStringArrayMixin, ArrowExtensionArray, BaseStringAr
         return result
 
     def _cmp_method(self, other, op):
+        if (
+            isinstance(other, (BaseStringArray, ArrowExtensionArray))
+            and self.dtype.na_value is not libmissing.NA
+            and other.dtype.na_value is libmissing.NA
+        ):
+            # NA has priority of NaN semantics
+            return NotImplemented
+
         result = super()._cmp_method(other, op)
         if self.dtype.na_value is np.nan:
             if op == operator.ne:
diff --git a/pandas/core/frame.py b/pandas/core/frame.py
index 6158e19737..ce0776b7ef 100644
--- a/pandas/core/frame.py
+++ b/pandas/core/frame.py
@@ -112,6 +112,10 @@ from pandas.core.dtypes.dtypes import (
     BaseMaskedDtype,
     ExtensionDtype,
 )
+from pandas.core.dtypes.generic import (
+    ABCIndex,
+    ABCSeries,
+)
 from pandas.core.dtypes.missing import (
     isna,
     notna,
@@ -795,12 +799,12 @@ class DataFrame(NDFrame, OpsMixin):
                     dtype,
                     copy,
                 )
-            elif getattr(data, "name", None) is not None:
+            elif isinstance(data, (ABCSeries, ABCIndex)) and data.name is not None:
                 # i.e. Series/Index with non-None name
                 mgr = dict_to_mgr(
                     # error: Item "ndarray" of "Union[ndarray, Series, Index]" has no
                     # attribute "name"
-                    {data.name: data},  # type: ignore[union-attr]
+                    {data.name: data},
                     index,
                     columns,
                     dtype=dtype,
@@ -9854,7 +9858,7 @@ class DataFrame(NDFrame, OpsMixin):
         ----------
         level : int, str, or list of these, default -1 (last level)
             Level(s) of index to unstack, can pass level name.
-        fill_value : int, str or dict
+        fill_value : scalar
             Replace NaN with this value if the unstack produces missing values.
         sort : bool, default True
             Sort the level(s) in the resulting MultiIndex columns.
diff --git a/pandas/core/ops/invalid.py b/pandas/core/ops/invalid.py
index 395db1617c..62aa79a881 100644
--- a/pandas/core/ops/invalid.py
+++ b/pandas/core/ops/invalid.py
@@ -25,7 +25,7 @@ if TYPE_CHECKING:
 
 def invalid_comparison(
     left: ArrayLike,
-    right: ArrayLike | Scalar,
+    right: ArrayLike | list | Scalar,
     op: Callable[[Any, Any], bool],
 ) -> npt.NDArray[np.bool_]:
     """


Test patch:
diff --git a/pandas/tests/arrays/string_/test_string.py b/pandas/tests/arrays/string_/test_string.py
index 5670fad7e2..736c0e1782 100644
--- a/pandas/tests/arrays/string_/test_string.py
+++ b/pandas/tests/arrays/string_/test_string.py
@@ -10,10 +10,12 @@ import pytest
 
 from pandas._config import using_string_dtype
 
+from pandas.compat import HAS_PYARROW
 from pandas.compat.pyarrow import (
     pa_version_under12p0,
     pa_version_under19p0,
 )
+import pandas.util._test_decorators as td
 
 from pandas.core.dtypes.common import is_dtype_equal
 
@@ -45,6 +47,25 @@ def cls(dtype):
     return dtype.construct_array_type()
 
 
+def string_dtype_highest_priority(dtype1, dtype2):
+    if HAS_PYARROW:
+        DTYPE_HIERARCHY = [
+            pd.StringDtype("python", na_value=np.nan),
+            pd.StringDtype("pyarrow", na_value=np.nan),
+            pd.StringDtype("python", na_value=pd.NA),
+            pd.StringDtype("pyarrow", na_value=pd.NA),
+        ]
+    else:
+        DTYPE_HIERARCHY = [
+            pd.StringDtype("python", na_value=np.nan),
+            pd.StringDtype("python", na_value=pd.NA),
+        ]
+
+    h1 = DTYPE_HIERARCHY.index(dtype1)
+    h2 = DTYPE_HIERARCHY.index(dtype2)
+    return DTYPE_HIERARCHY[max(h1, h2)]
+
+
 def test_dtype_constructor():
     pytest.importorskip("pyarrow")
 
@@ -331,13 +352,18 @@ def test_comparison_methods_scalar_not_string(comparison_op, dtype):
         tm.assert_extension_array_equal(result, expected)
 
 
-def test_comparison_methods_array(comparison_op, dtype):
+def test_comparison_methods_array(comparison_op, dtype, dtype2):
     op_name = f"__{comparison_op.__name__}__"
 
     a = pd.array(["a", None, "c"], dtype=dtype)
-    other = [None, None, "c"]
-    result = getattr(a, op_name)(other)
-    if dtype.na_value is np.nan:
+    other = pd.array([None, None, "c"], dtype=dtype2)
+    result = comparison_op(a, other)
+
+    # ensure operation is commutative
+    result2 = comparison_op(other, a)
+    tm.assert_equal(result, result2)
+
+    if dtype.na_value is np.nan and dtype2.na_value is np.nan:
         if operator.ne == comparison_op:
             expected = np.array([True, True, False])
         else:
@@ -345,11 +371,56 @@ def test_comparison_methods_array(comparison_op, dtype):
             expected[-1] = getattr(other[-1], op_name)(a[-1])
         tm.assert_numpy_array_equal(result, expected)
 
-        result = getattr(a, op_name)(pd.NA)
+    else:
+        max_dtype = string_dtype_highest_priority(dtype, dtype2)
+        if max_dtype.storage == "python":
+            expected_dtype = "boolean"
+        else:
+            expected_dtype = "bool[pyarrow]"
+
+        expected = np.full(len(a), fill_value=None, dtype="object")
+        expected[-1] = getattr(other[-1], op_name)(a[-1])
+        expected = pd.array(expected, dtype=expected_dtype)
+        tm.assert_extension_array_equal(result, expected)
+
+
+@td.skip_if_no("pyarrow")
+def test_comparison_methods_array_arrow_extension(comparison_op, dtype2):
+    # Test pd.ArrowDtype(pa.string()) against other string arrays
+    import pyarrow as pa
+
+    op_name = f"__{comparison_op.__name__}__"
+    dtype = pd.ArrowDtype(pa.string())
+    a = pd.array(["a", None, "c"], dtype=dtype)
+    other = pd.array([None, None, "c"], dtype=dtype2)
+    result = comparison_op(a, other)
+
+    # ensure operation is commutative
+    result2 = comparison_op(other, a)
+    tm.assert_equal(result, result2)
+
+    expected = pd.array([None, None, True], dtype="bool[pyarrow]")
+    expected[-1] = getattr(other[-1], op_name)(a[-1])
+    tm.assert_extension_array_equal(result, expected)
+
+
+def test_comparison_methods_list(comparison_op, dtype):
+    op_name = f"__{comparison_op.__name__}__"
+
+    a = pd.array(["a", None, "c"], dtype=dtype)
+    other = [None, None, "c"]
+    result = comparison_op(a, other)
+
+    # ensure operation is commutative
+    result2 = comparison_op(other, a)
+    tm.assert_equal(result, result2)
+
+    if dtype.na_value is np.nan:
         if operator.ne == comparison_op:
-            expected = np.array([True, True, True])
+            expected = np.array([True, True, False])
         else:
             expected = np.array([False, False, False])
+            expected[-1] = getattr(other[-1], op_name)(a[-1])
         tm.assert_numpy_array_equal(result, expected)
 
     else:
@@ -359,10 +430,6 @@ def test_comparison_methods_array(comparison_op, dtype):
         expected = pd.array(expected, dtype=expected_dtype)
         tm.assert_extension_array_equal(result, expected)
 
-        result = getattr(a, op_name)(pd.NA)
-        expected = pd.array([None, None, None], dtype=expected_dtype)
-        tm.assert_extension_array_equal(result, expected)
-
 
 def test_constructor_raises(cls):
     if cls is pd.arrays.StringArray:
diff --git a/pandas/tests/extension/test_string.py b/pandas/tests/extension/test_string.py
index 2512911118..96c014f549 100644
--- a/pandas/tests/extension/test_string.py
+++ b/pandas/tests/extension/test_string.py
@@ -31,6 +31,7 @@ import pandas._testing as tm
 from pandas.api.types import is_string_dtype
 from pandas.core.arrays import ArrowStringArray
 from pandas.core.arrays.string_ import StringDtype
+from pandas.tests.arrays.string_.test_string import string_dtype_highest_priority
 from pandas.tests.extension import base
 
 
@@ -202,10 +203,13 @@ class TestStringArray(base.ExtensionTests):
         dtype = cast(StringDtype, tm.get_dtype(obj))
         if op_name in ["__add__", "__radd__"]:
             cast_to = dtype
+            dtype_other = tm.get_dtype(other) if not isinstance(other, str) else None
+            if isinstance(dtype_other, StringDtype):
+                cast_to = string_dtype_highest_priority(dtype, dtype_other)
         elif dtype.na_value is np.nan:
             cast_to = np.bool_  # type: ignore[assignment]
         elif dtype.storage == "pyarrow":
-            cast_to = "boolean[pyarrow]"  # type: ignore[assignment]
+            cast_to = "bool[pyarrow]"  # type: ignore[assignment]
         else:
             cast_to = "boolean"  # type: ignore[assignment]
         return pointwise_result.astype(cast_to)
@@ -236,10 +240,10 @@ class TestStringArray(base.ExtensionTests):
         if (
             using_infer_string
             and all_arithmetic_operators == "__radd__"
-            and (
-                (dtype.na_value is pd.NA) or (dtype.storage == "python" and HAS_PYARROW)
-            )
+            and dtype.na_value is pd.NA
+            and (HAS_PYARROW or dtype.storage == "pyarrow")
         ):
+            # TODO(infer_string)
             mark = pytest.mark.xfail(
                 reason="The pointwise operation result will be inferred to "
                 "string[nan, pyarrow], which does not match the input dtype"
diff --git a/pandas/tests/frame/test_constructors.py b/pandas/tests/frame/test_constructors.py
index 037a2ae294..2426c89dbc 100644
--- a/pandas/tests/frame/test_constructors.py
+++ b/pandas/tests/frame/test_constructors.py
@@ -2780,6 +2780,19 @@ class TestDataFrameConstructors:
         )
         tm.assert_frame_equal(result, expected)
 
+    def test_dataframe_from_array_like_with_name_attribute(self):
+        # GH#61443
+        class DummyArray(np.ndarray):
+            def __new__(cls, input_array):
+                obj = np.asarray(input_array).view(cls)
+                obj.name = "foo"
+                return obj
+
+        dummy = DummyArray(np.eye(3))
+        df = DataFrame(dummy)
+        expected = DataFrame(np.eye(3))
+        tm.assert_frame_equal(df, expected)
+
 
 class TestDataFrameConstructorIndexInference:
     def test_frame_from_dict_of_series_overlapping_monthly_period_indexes(self):