TYP: require Index objects earlier in internals

pandas/core/internals/__init__.py

@@ -18,8 +18,6 @@
     BlockManager,
     SingleBlockManager,
     concatenate_block_managers,
-    create_block_manager_from_arrays,
-    create_block_manager_from_blocks,
 )
 
 __all__ = [
@@ -40,6 +38,4 @@
     "BlockManager",
     "SingleBlockManager",
     "concatenate_block_managers",
-    "create_block_manager_from_arrays",
-    "create_block_manager_from_blocks",
 ]

pandas/core/internals/construction.py

@@ -29,7 +29,6 @@
     ABCDataFrame,
     ABCDatetimeIndex,
     ABCIndexClass,
-    ABCPeriodIndex,
     ABCSeries,
     ABCTimedeltaIndex,
 )
@@ -44,7 +43,7 @@
     get_objs_combined_axis,
     union_indexes,
 )
-from pandas.core.internals import (
+from pandas.core.internals.managers import (
     create_block_manager_from_arrays,
     create_block_manager_from_blocks,
 )
@@ -53,12 +52,16 @@
 # BlockManager Interface
 
 
-def arrays_to_mgr(arrays, arr_names, index, columns, dtype=None, verify_integrity=True):
+def arrays_to_mgr(
+    arrays, arr_names, index, columns, dtype=None, verify_integrity: bool = True
+):
     """
     Segregate Series based on type and coerce into matrices.
 
     Needs to handle a lot of exceptional cases.
     """
+    arr_names = ensure_index(arr_names)
+
     if verify_integrity:
         # figure out the index, if necessary
         if index is None:
@@ -74,6 +77,8 @@ def arrays_to_mgr(arrays, arr_names, index, columns, dtype=None, verify_integrit
     # from BlockManager perspective
     axes = [columns, index]
 
+    assert isinstance(columns, Index), type(columns)
+    assert isinstance(index, Index), type(index)
     return create_block_manager_from_arrays(arrays, arr_names, axes)
 
 
@@ -163,7 +168,8 @@ def init_ndarray(values, index, columns, dtype=None, copy=False):
             values = [values]
 
         if columns is None:
-            columns = list(range(len(values)))
+            columns = Index(range(len(values)))
+
         return arrays_to_mgr(values, columns, index, columns, dtype=dtype)
 
     # by definition an array here
@@ -209,6 +215,8 @@ def init_ndarray(values, index, columns, dtype=None, copy=False):
     else:
         block_values = [values]
 
+    assert isinstance(columns, Index), type(columns)
+    assert isinstance(index, Index), type(index)
     return create_block_manager_from_blocks(block_values, [columns, index])
 
 
@@ -635,12 +643,7 @@ def sanitize_index(data, index: Index):
     if len(data) != len(index):
         raise ValueError("Length of values does not match length of index")
 
-    if isinstance(data, ABCIndexClass):
-        pass
-    elif isinstance(data, (ABCPeriodIndex, ABCDatetimeIndex)):
-        data = data._values
-
-    elif isinstance(data, np.ndarray):
+    if isinstance(data, np.ndarray):
 
         # coerce datetimelike types
         if data.dtype.kind in ["M", "m"]:

pandas/core/internals/managers.py

@@ -342,7 +342,7 @@ def _verify_integrity(self) -> None:
         tot_items = sum(len(x.mgr_locs) for x in self.blocks)
         for block in self.blocks:
             if block._verify_integrity and block.shape[1:] != mgr_shape[1:]:
-                construction_error(tot_items, block.shape[1:], self.axes)
+                raise construction_error(tot_items, block.shape[1:], self.axes)
         if len(self.items) != tot_items:
             raise AssertionError(
                 "Number of manager items must equal union of "
@@ -1657,7 +1657,7 @@ def concat(self, to_concat, new_axis: Index) -> "SingleBlockManager":
 # Constructor Helpers
 
 
-def create_block_manager_from_blocks(blocks, axes):
+def create_block_manager_from_blocks(blocks, axes: List[Index]) -> BlockManager:
     try:
         if len(blocks) == 1 and not isinstance(blocks[0], Block):
             # if blocks[0] is of length 0, return empty blocks
@@ -1678,18 +1678,23 @@ def create_block_manager_from_blocks(blocks, axes):
     except ValueError as e:
         blocks = [getattr(b, "values", b) for b in blocks]
         tot_items = sum(b.shape[0] for b in blocks)
-        construction_error(tot_items, blocks[0].shape[1:], axes, e)
+        raise construction_error(tot_items, blocks[0].shape[1:], axes, e)
 
 
-def create_block_manager_from_arrays(arrays, names, axes):
+def create_block_manager_from_arrays(
+    arrays, names: Index, axes: List[Index]
+) -> BlockManager:
+    assert isinstance(names, Index)
+    assert isinstance(axes, list)
+    assert all(isinstance(x, Index) for x in axes)
 
     try:
         blocks = form_blocks(arrays, names, axes)
         mgr = BlockManager(blocks, axes)
         mgr._consolidate_inplace()
         return mgr
     except ValueError as e:
-        construction_error(len(arrays), arrays[0].shape, axes, e)
+        raise construction_error(len(arrays), arrays[0].shape, axes, e)
 
 
 def construction_error(tot_items, block_shape, axes, e=None):
@@ -1704,23 +1709,25 @@ def construction_error(tot_items, block_shape, axes, e=None):
     if len(implied) <= 2:
         implied = implied[::-1]
 
+    # We return the exception object instead of raising it so that we
+    #  can raise it in the caller; mypy plays better with that
     if passed == implied and e is not None:
-        raise e
+        return e
     if block_shape[0] == 0:
-        raise ValueError("Empty data passed with indices specified.")
-    raise ValueError(f"Shape of passed values is {passed}, indices imply {implied}")
+        return ValueError("Empty data passed with indices specified.")
+    return ValueError(f"Shape of passed values is {passed}, indices imply {implied}")
 
 
 # -----------------------------------------------------------------------
 
 
-def form_blocks(arrays, names, axes):
+def form_blocks(arrays, names: Index, axes) -> List[Block]:
     # put "leftover" items in float bucket, where else?
     # generalize?
-    items_dict = defaultdict(list)
+    items_dict: Dict[str, List] = defaultdict(list)
     extra_locs = []
 
-    names_idx = ensure_index(names)
+    names_idx = names
     if names_idx.equals(axes[0]):
         names_indexer = np.arange(len(names_idx))
     else:
@@ -1738,7 +1745,7 @@ def form_blocks(arrays, names, axes):
         block_type = get_block_type(v)
         items_dict[block_type.__name__].append((i, k, v))
 
-    blocks = []
+    blocks: List[Block] = []
     if len(items_dict["FloatBlock"]):
         float_blocks = _multi_blockify(items_dict["FloatBlock"])
         blocks.extend(float_blocks)