From 10b23630fe341c7b730401e341eb1c8a1f37feff Mon Sep 17 00:00:00 2001
From: janez <janez.demsar@fri.uni-lj.si>
Date: Fri, 4 Oct 2024 15:02:26 +0200
Subject: [PATCH 1/2] BUG: Fix SparseFrameAccessor.to_dense return type

---
 doc/source/whatsnew/v3.0.0.rst              | 1 +
 pandas/core/arrays/sparse/accessor.py       | 5 ++---
 pandas/tests/arrays/sparse/test_accessor.py | 4 ++++
 3 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/doc/source/whatsnew/v3.0.0.rst b/doc/source/whatsnew/v3.0.0.rst
index a5b4560a47bc4..f99b709484df9 100644
--- a/doc/source/whatsnew/v3.0.0.rst
+++ b/doc/source/whatsnew/v3.0.0.rst
@@ -682,6 +682,7 @@ Sparse
 ^^^^^^
 - Bug in :class:`SparseDtype` for equal comparison with na fill value. (:issue:`54770`)
 - Bug in :meth:`DataFrame.sparse.from_spmatrix` which hard coded an invalid ``fill_value`` for certain subtypes. (:issue:`59063`)
+- Bug in :meth:`DataFrame.sparse.to_dense` which ignored subclassing and always returned an instance of :class:`DataFrame` (:issue:`59913`)
 
 ExtensionArray
 ^^^^^^^^^^^^^^
diff --git a/pandas/core/arrays/sparse/accessor.py b/pandas/core/arrays/sparse/accessor.py
index e610e018c5a74..ff0cb9e1df75e 100644
--- a/pandas/core/arrays/sparse/accessor.py
+++ b/pandas/core/arrays/sparse/accessor.py
@@ -369,10 +369,9 @@ def to_dense(self) -> DataFrame:
         1  1
         2  0
         """
-        from pandas import DataFrame
-
         data = {k: v.array.to_dense() for k, v in self._parent.items()}
-        return DataFrame(data, index=self._parent.index, columns=self._parent.columns)
+        return self._parent._constructor(
+            data, index=self._parent.index, columns=self._parent.columns)
 
     def to_coo(self) -> spmatrix:
         """
diff --git a/pandas/tests/arrays/sparse/test_accessor.py b/pandas/tests/arrays/sparse/test_accessor.py
index bd3298940ae3a..08bfd5b69fdd9 100644
--- a/pandas/tests/arrays/sparse/test_accessor.py
+++ b/pandas/tests/arrays/sparse/test_accessor.py
@@ -252,3 +252,7 @@ def test_with_column_named_sparse(self):
         # https://github.com/pandas-dev/pandas/issues/30758
         df = pd.DataFrame({"sparse": pd.arrays.SparseArray([1, 2])})
         assert isinstance(df.sparse, pd.core.arrays.sparse.accessor.SparseFrameAccessor)
+
+    def test_subclassing(self):
+        df = tm.SubclassedDataFrame({"sparse": pd.arrays.SparseArray([1, 2])})
+        assert isinstance(df.sparse.to_dense(), tm.SubclassedDataFrame)

From 12a5c7b58c9cbb363861b6d2aedec7fcf78ad50b Mon Sep 17 00:00:00 2001
From: "pre-commit-ci[bot]"
 <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Date: Fri, 4 Oct 2024 21:22:30 +0000
Subject: [PATCH 2/2] [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci
---
 pandas/core/arrays/sparse/accessor.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/pandas/core/arrays/sparse/accessor.py b/pandas/core/arrays/sparse/accessor.py
index ff0cb9e1df75e..8083371ed171a 100644
--- a/pandas/core/arrays/sparse/accessor.py
+++ b/pandas/core/arrays/sparse/accessor.py
@@ -371,7 +371,8 @@ def to_dense(self) -> DataFrame:
         """
         data = {k: v.array.to_dense() for k, v in self._parent.items()}
         return self._parent._constructor(
-            data, index=self._parent.index, columns=self._parent.columns)
+            data, index=self._parent.index, columns=self._parent.columns
+        )
 
     def to_coo(self) -> spmatrix:
         """