Add IndexedFrame class and move SingleColumnFrame to a separate module

python/.flake8

@@ -4,14 +4,19 @@
 exclude = __init__.py
 ignore =
     # line break before binary operator
-    W503
+    W503,
     # whitespace before :
     E203
 
 [pydocstyle]
-match = ^(.*abc\.py|types\.py)$
-#match = ^(types\.py)$
+match = ^(.*abc\.py|.*api/types\.py|.*single_column_frame\.py|.*indexed_frame\.py)$
 # Due to https://github.com/PyCQA/pydocstyle/issues/363, we must exclude rather than include using match-dir.
 match-dir = ^(?!ci|cpp|python/dask_cudf|python/cudf_kafka|python/custreamz).*$
-# In addition to numpy style, we additionally ignore magic methods (D105) and newlines before docstrings (D204).
-add-ignore = D105, D204
+# In addition to numpy style, we additionally ignore:
+add-ignore =
+    # magic methods
+    D105,
+    # no docstring in __init__
+    D107,
+    # newlines before docstrings
+    D204

python/cudf/cudf/core/_internals/where.py

@@ -10,9 +10,10 @@
 from cudf._typing import ColumnLike, ScalarLike
 from cudf.core.column import ColumnBase
 from cudf.core.dataframe import DataFrame
-from cudf.core.frame import Frame, SingleColumnFrame
+from cudf.core.frame import Frame
 from cudf.core.index import Index
 from cudf.core.series import Series
+from cudf.core.single_column_frame import SingleColumnFrame
 
 
 def _normalize_scalars(col: ColumnBase, other: ScalarLike) -> ScalarLike:

python/cudf/cudf/core/column/column.py

@@ -81,7 +81,9 @@ def as_frame(self) -> "cudf.core.frame.Frame":
         """
         Converts a Column to Frame
         """
-        return cudf.core.frame.SingleColumnFrame({None: self.copy(deep=False)})
+        return cudf.core.single_column_frame.SingleColumnFrame(
+            {None: self.copy(deep=False)}
+        )
 
     @property
     def data_array_view(self) -> "cuda.devicearray.DeviceNDArray":