DEPR: maybe_infer_ndim (#61901)

Author: jbrockmendel

doc/source/whatsnew/v3.0.0.rst

@@ -457,6 +457,7 @@ Other Deprecations
 - Deprecated :meth:`.DataFrameGroupby.corrwith` (:issue:`57158`)
 - Deprecated :meth:`Timestamp.utcfromtimestamp`, use ``Timestamp.fromtimestamp(ts, "UTC")`` instead (:issue:`56680`)
 - Deprecated :meth:`Timestamp.utcnow`, use ``Timestamp.now("UTC")`` instead (:issue:`56680`)
+- Deprecated ``pd.core.internals.api.maybe_infer_ndim`` (:issue:`40226`)
 - Deprecated allowing non-keyword arguments in :meth:`DataFrame.all`, :meth:`DataFrame.min`, :meth:`DataFrame.max`, :meth:`DataFrame.sum`, :meth:`DataFrame.prod`, :meth:`DataFrame.mean`, :meth:`DataFrame.median`, :meth:`DataFrame.sem`, :meth:`DataFrame.var`, :meth:`DataFrame.std`, :meth:`DataFrame.skew`, :meth:`DataFrame.kurt`, :meth:`Series.all`,  :meth:`Series.min`, :meth:`Series.max`, :meth:`Series.sum`, :meth:`Series.prod`, :meth:`Series.mean`, :meth:`Series.median`, :meth:`Series.sem`, :meth:`Series.var`, :meth:`Series.std`, :meth:`Series.skew`, and :meth:`Series.kurt`. (:issue:`57087`)
 - Deprecated allowing non-keyword arguments in :meth:`Series.to_markdown` except ``buf``. (:issue:`57280`)
 - Deprecated allowing non-keyword arguments in :meth:`Series.to_string` except ``buf``. (:issue:`57280`)

pandas/_libs/internals.pyx

@@ -709,9 +709,9 @@ cdef class Block:
             self.ndim = state[2]
         else:
             # older pickle
-            from pandas.core.internals.api import maybe_infer_ndim
+            from pandas.core.internals.api import _maybe_infer_ndim
 
-            ndim = maybe_infer_ndim(self.values, self.mgr_locs)
+            ndim = _maybe_infer_ndim(self.values, self.mgr_locs)
             self.ndim = ndim
 
     cpdef Block slice_block_rows(self, slice slicer):

pandas/core/internals/api.py

@@ -136,7 +136,7 @@ def make_block(
     if not isinstance(placement, BlockPlacement):
         placement = BlockPlacement(placement)
 
-    ndim = maybe_infer_ndim(values, placement, ndim)
+    ndim = _maybe_infer_ndim(values, placement, ndim)
     if isinstance(values.dtype, (PeriodDtype, DatetimeTZDtype)):
         # GH#41168 ensure we can pass 1D dt64tz values
         # More generally, any EA dtype that isn't is_1d_only_ea_dtype
@@ -148,7 +148,7 @@ def make_block(
     return klass(values, ndim=ndim, placement=placement)
 
 
-def maybe_infer_ndim(values, placement: BlockPlacement, ndim: int | None) -> int:
+def _maybe_infer_ndim(values, placement: BlockPlacement, ndim: int | None) -> int:
     """
     If `ndim` is not provided, infer it from placement and values.
     """
@@ -162,3 +162,15 @@ def maybe_infer_ndim(values, placement: BlockPlacement, ndim: int | None) -> int
         else:
             ndim = values.ndim
     return ndim
+
+
+def maybe_infer_ndim(values, placement: BlockPlacement, ndim: int | None) -> int:
+    """
+    If `ndim` is not provided, infer it from placement and values.
+    """
+    warnings.warn(
+        "maybe_infer_ndim is deprecated and will be removed in a future version.",
+        DeprecationWarning,
+        stacklevel=2,
+    )
+    return _maybe_infer_ndim(values, placement, ndim)

pandas/tests/internals/test_api.py

@@ -79,6 +79,15 @@ def test_create_block_manager_from_blocks_deprecated():
         internals.create_block_manager_from_blocks
 
 
+def test_maybe_infer_ndim_deprecated():
+    # GH#40226
+    msg = "maybe_infer_ndim is deprecated and will be removed in a future version."
+    arr = np.arange(5)
+    bp = pd._libs.internals.BlockPlacement([1])
+    with tm.assert_produces_warning(DeprecationWarning, match=msg):
+        internals.api.maybe_infer_ndim(arr, bp, 1)
+
+
 def test_create_dataframe_from_blocks(float_frame):
     block = float_frame._mgr.blocks[0]
     index = float_frame.index.copy()