DEPR: Remove SparseDataFrame/Series pickle compat (#49316)

* DEPR: Remove SparseDataFrame/Series pickle compat

* Add to whatsnew

doc/source/whatsnew/v2.0.0.rst

@@ -228,7 +228,7 @@ Removal of prior version deprecations/changes
 - Removed ``pandas.util.testing`` in favor of ``pandas.testing`` (:issue:`30745`)
 - Removed :meth:`Series.str.__iter__` (:issue:`28277`)
 - Removed ``pandas.SparseArray`` in favor of :class:`arrays.SparseArray` (:issue:`30642`)
-- Removed ``pandas.SparseSeries`` and ``pandas.SparseDataFrame`` (:issue:`30642`)
+- Removed ``pandas.SparseSeries`` and ``pandas.SparseDataFrame``, including pickle support. (:issue:`30642`)
 - Enforced disallowing a string column label into ``times`` in :meth:`DataFrame.ewm` (:issue:`43265`)
 - Enforced disallowing a tuple of column labels into :meth:`.DataFrameGroupBy.__getitem__` (:issue:`30546`)
 - Removed setting Categorical._codes directly (:issue:`41429`)

pandas/compat/pickle_compat.py

@@ -7,11 +7,7 @@
 import copy
 import io
 import pickle as pkl
-from typing import (
-    TYPE_CHECKING,
-    Generator,
-)
-import warnings
+from typing import Generator
 
 import numpy as np
 
@@ -26,12 +22,6 @@
 )
 from pandas.core.internals import BlockManager
 
-if TYPE_CHECKING:
-    from pandas import (
-        DataFrame,
-        Series,
-    )
-
 
 def load_reduce(self):
     stack = self.stack
@@ -68,49 +58,6 @@ def load_reduce(self):
         raise
 
 
-_sparse_msg = """\
-
-Loading a saved '{cls}' as a {new} with sparse values.
-'{cls}' is now removed. You should re-save this dataset in its new format.
-"""
-
-
-class _LoadSparseSeries:
-    # To load a SparseSeries as a Series[Sparse]
-
-    # https://github.com/python/mypy/issues/1020
-    # error: Incompatible return type for "__new__" (returns "Series", but must return
-    # a subtype of "_LoadSparseSeries")
-    def __new__(cls) -> Series:  # type: ignore[misc]
-        from pandas import Series
-
-        warnings.warn(
-            _sparse_msg.format(cls="SparseSeries", new="Series"),
-            FutureWarning,
-            stacklevel=6,
-        )
-
-        return Series(dtype=object)
-
-
-class _LoadSparseFrame:
-    # To load a SparseDataFrame as a DataFrame[Sparse]
-
-    # https://github.com/python/mypy/issues/1020
-    # error: Incompatible return type for "__new__" (returns "DataFrame", but must
-    # return a subtype of "_LoadSparseFrame")
-    def __new__(cls) -> DataFrame:  # type: ignore[misc]
-        from pandas import DataFrame
-
-        warnings.warn(
-            _sparse_msg.format(cls="SparseDataFrame", new="DataFrame"),
-            FutureWarning,
-            stacklevel=6,
-        )
-
-        return DataFrame()
-
-
 # If classes are moved, provide compat here.
 _class_locations_map = {
     ("pandas.core.sparse.array", "SparseArray"): ("pandas.core.arrays", "SparseArray"),
@@ -144,14 +91,6 @@ def __new__(cls) -> DataFrame:  # type: ignore[misc]
         "pandas.core.arrays.sparse",
         "SparseArray",
     ),
-    ("pandas.sparse.series", "SparseSeries"): (
-        "pandas.compat.pickle_compat",
-        "_LoadSparseSeries",
-    ),
-    ("pandas.sparse.frame", "SparseDataFrame"): (
-        "pandas.core.sparse.frame",
-        "_LoadSparseFrame",
-    ),
     ("pandas.indexes.base", "_new_Index"): ("pandas.core.indexes.base", "_new_Index"),
     ("pandas.indexes.base", "Index"): ("pandas.core.indexes.base", "Index"),
     ("pandas.indexes.numeric", "Int64Index"): (
@@ -183,14 +122,6 @@ def __new__(cls) -> DataFrame:  # type: ignore[misc]
         "pandas.core.indexes.numeric",
         "Float64Index",
     ),
-    ("pandas.core.sparse.series", "SparseSeries"): (
-        "pandas.compat.pickle_compat",
-        "_LoadSparseSeries",
-    ),
-    ("pandas.core.sparse.frame", "SparseDataFrame"): (
-        "pandas.compat.pickle_compat",
-        "_LoadSparseFrame",
-    ),
 }
 
 

pandas/tests/io/test_pickle.py

@@ -254,28 +254,6 @@ def test_pickle_path_localpath():
     tm.assert_frame_equal(df, result)
 
 
-@pytest.mark.parametrize("typ", ["sparseseries", "sparseframe"])
-def test_legacy_sparse_warning(datapath, typ):
-    """
-
-    Generated with
-
-    >>> df = pd.DataFrame({"A": [1, 2, 3, 4], "B": [0, 0, 1, 1]}).to_sparse()
-    >>> df.to_pickle("pandas/tests/io/data/pickle/sparseframe-0.20.3.pickle.gz",
-    ...              compression="gzip")
-
-    >>> s = df['B']
-    >>> s.to_pickle("pandas/tests/io/data/pickle/sparseseries-0.20.3.pickle.gz",
-    ...             compression="gzip")
-    """
-    with tm.assert_produces_warning(FutureWarning):
-        simplefilter("ignore", DeprecationWarning)  # from boto
-        pd.read_pickle(
-            datapath("io", "data", "pickle", f"{typ}-0.20.3.pickle.gz"),
-            compression="gzip",
-        )
-
-
 # ---------------------
 # test pickle compression
 # ---------------------