FIX: Cleanup messed up files for PR

doc/source/whatsnew/v0.23.0.txt

@@ -353,7 +353,7 @@ Reshaping
 - Bug in :func:`Series.rank` where ``Series`` containing ``NaT`` modifies the ``Series`` inplace (:issue:`18521`)
 - Bug in :func:`cut` which fails when using readonly arrays (:issue:`18773`)
 - Bug in :func:`Dataframe.pivot_table` which fails when the ``aggfunc`` arg is of type string.  The behavior is now consistent with other methods like ``agg`` and ``apply`` (:issue:`18713`)
-- Bug in :func:`get_dummies` which doesn't cast all columns as sparse which causes reindex to fail. (:issue:`18914`)
+- Bug in :func:`pandas.core.dtypes.concat._get_series_result_type` which returns SparseDataFrame even if not all contained in Frame are sparse. (:issue:`18914`)
 
 
 Numeric

pandas/core/internals.py

@@ -2756,11 +2756,6 @@ class SparseBlock(NonConsolidatableMixIn, Block):
     _holder = SparseArray
     _concatenator = staticmethod(_concat._concat_sparse)
 
-    def __init__(self, values, placement, ndim=None, fastpath=False, **kwargs):
-        super(SparseBlock, self).__init__(self._holder(values),
-                                            placement, ndim=ndim,
-                                                fastpath=fastpath, **kwargs)
-
     @property
     def shape(self):
         return (len(self.mgr_locs), self.sp_index.length)

pandas/core/sparse/frame.py

@@ -14,7 +14,7 @@
 from pandas.core.dtypes.cast import maybe_upcast, find_common_type
 from pandas.core.dtypes.common import _ensure_platform_int, is_scipy_sparse
 
-from pandas.core.common import _try_sort, is_sparse
+from pandas.core.common import _try_sort
 from pandas.compat.numpy import function as nv
 from pandas.core.index import Index, MultiIndex, _ensure_index
 from pandas.core.series import Series

pandas/tests/reshape/test_reshape.py

@@ -454,7 +454,7 @@ def test_dataframe_dummies_preserve_categorical_dtype(self, dtype):
 
             tm.assert_frame_equal(result, expected)
 
-    def test_get_dummies_sparsify_all_columns(self):
+    def test_get_dummies_dont_sparsify_all_columns(self):
         # GH18914
         df = DataFrame.from_items([('GDP', [1, 2]), ('Nation', ['AB', 'CD'])])
         df = get_dummies(df, columns=['Nation'], sparse=True)

pandas/tests/sparse/test_array.py

@@ -465,7 +465,7 @@ def test_to_dense(self):
         with tm.assert_produces_warning(FutureWarning,
                                         check_stacklevel=False):
             SparseArray(vals).to_dense(fill=2)
-    
+
     def test_getitem(self):
         def _checkit(i):
             assert_almost_equal(self.arr[i], self.arr.values[i])

pandas/tests/sparse/test_frame.py

@@ -322,6 +322,9 @@ def test_density(self):
 
         assert df.density == 0.75
 
+    def test_sparse_to_dense(self):
+        pass
+
     def test_sparse_series_ops(self):
         self._check_frame_ops(self.frame)