Refactor and some fixes

Signed-off-by: Igoshev, Yaroslav <yaroslav.igoshev@intel.com>

modin/core/dataframe/base/dataframe/protocol/test/__init__.py

@@ -10,3 +10,5 @@
 # the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF
 # ANY KIND, either express or implied. See the License for the specific language
 # governing permissions and limitations under the License.
+
+"""Tests for the DataFrame exchange protocol."""

modin/core/dataframe/base/dataframe/protocol/test/test_sanity.py

@@ -11,15 +11,15 @@
 # ANY KIND, either express or implied. See the License for the specific language
 # governing permissions and limitations under the License.
 
-"""Perform basic sanity checks for the DataFrame exchange protocol."""
+"""Basic sanity checks for the DataFrame exchange protocol."""
 
 import pytest
 import modin.pandas as pd
 
 
 def test_sanity():
     """Test that the DataFrame protocol module is valid and could be imported correctly."""
-    from modin.core.dataframe.base.dataframe.protocol.dataframe import (  # noqa
+    from modin.core.dataframe.base.dataframe.protocol import (  # noqa
         ProtocolDataframe,
     )
 
@@ -31,7 +31,7 @@ class TestPassed(BaseException):
         pass
 
     def dummy_io_method(*args, **kwargs):
-        """Dummy method emulating that the code path reached exchange protocol implementation."""
+        """Dummy method emulating that the code path reached the exchange protocol implementation."""
         raise TestPassed
 
     from modin.core.storage_formats.base.query_compiler import BaseQueryCompiler

modin/core/dataframe/base/dataframe/protocol/test/test_utils.py

@@ -11,7 +11,7 @@
 # ANY KIND, either express or implied. See the License for the specific language
 # governing permissions and limitations under the License.
 
-"""Test common utility functions for the DataFrame exchange protocol."""
+"""Tests for common utility functions of the DataFrame exchange protocol."""
 
 import pytest
 import pandas

modin/core/execution/dispatching/factories/factories.py

@@ -189,7 +189,7 @@ def _from_non_pandas(cls, *args, **kwargs):
     @classmethod
     @doc(
         _doc_io_method_template,
-        source="a DataFrame object supporting exchange protocol (__dataframe__())",
+        source="a DataFrame object supporting exchange protocol `__dataframe__()`",
         params=_doc_io_method_all_params,
         method="utils.from_dataframe",
     )

modin/core/io/io.py

@@ -105,12 +105,12 @@ def from_arrow(cls, at):
     @classmethod
     def from_dataframe(cls, df):
         """
-        Create a Modin `query_compiler` from a DataFrame object supporting exchange protocol (__dataframe__()).
+        Create a Modin QueryCompiler from a DataFrame supporting the DataFrame exchange protocol `__dataframe__()`.
 
         Parameters
         ----------
         df : DataFrame
-            The DataFrame object supporting dataframe exchange protocol.
+            The DataFrame object supporting the DataFrame exchange protocol.
 
         Returns
         -------

modin/core/storage_formats/base/query_compiler.py

@@ -363,7 +363,7 @@ def to_numpy(self, **kwargs):  # noqa: PR02
 
     # END To NumPy
 
-    # Exchange protocol
+    # Dataframe exchange protocol
 
     def to_dataframe(self, nan_as_null: bool = False, allow_copy: bool = True) -> dict:
         """
@@ -388,21 +388,21 @@ def to_dataframe(self, nan_as_null: bool = False, allow_copy: bool = True) -> di
         Returns
         -------
         dict
-            A dictionary object following the dataframe protocol specification.
+            A dictionary object following the DataFrame protocol specification.
         """
         raise NotImplementedError(
-            "The selected execution does not implement DataFrame exchange protocol."
+            "The selected execution does not implement the DataFrame exchange protocol."
         )
 
     @classmethod
     def from_dataframe(cls, df, data_cls):
         """
-        Build QueryCompiler from a DataFrame object supporting dataframe exchange protocol (__dataframe__()).
+        Build QueryCompiler from a DataFrame object supporting the dataframe exchange protocol `__dataframe__()`.
 
         Parameters
         ----------
         df : DataFrame
-            The DataFrame object supporting dataframe exchange protocol.
+            The DataFrame object supporting the dataframe exchange protocol.
         data_cls : type
             :py:class:`~modin.core.dataframe.pandas.dataframe.dataframe.PandasDataframe` class
             (or its descendant) to convert to.
@@ -413,10 +413,10 @@ def from_dataframe(cls, df, data_cls):
             QueryCompiler containing data from the DataFrame.
         """
         raise NotImplementedError(
-            "The selected execution does not implement import via dataframe exchange protocol."
+            "The selected execution does not implement import via the DataFrame exchange protocol."
         )
 
-    # END Exchange protocol
+    # END Dataframe exchange protocol
 
     # Abstract inter-data operations (e.g. add, sub)
     # These operations require two DataFrames and will change the shape of the

modin/pandas/base.py

@@ -556,35 +556,6 @@ def __constructor__(self, *args, **kwargs):
         """
         return type(self)(*args, **kwargs)
 
-    def __dataframe__(self, nan_as_null: bool = False, allow_copy: bool = True) -> dict:
-        """
-        Get a DataFrame exchange protocol object representing data of the Modin DataFrame.
-
-        See more about the protocol in https://data-apis.org/dataframe-protocol/latest/index.html.
-
-        Parameters
-        ----------
-        nan_as_null : bool, default: False
-            A keyword intended for the consumer to tell the producer
-            to overwrite null values in the data with ``NaN`` (or ``NaT``).
-            This currently has no effect; once support for nullable extension
-            dtypes is added, this value should be propagated to columns.
-        allow_copy : bool, default: True
-            A keyword that defines whether or not the library is allowed
-            to make a copy of the data. For example, copying data would be necessary
-            if a library supports strided buffers, given that this protocol
-            specifies contiguous buffers. Currently, if the flag is set to ``False``
-            and a copy is needed, a ``RuntimeError`` will be raised.
-
-        Returns
-        -------
-        dict
-            A dictionary object following the dataframe protocol specification.
-        """
-        return self._query_compiler.to_dataframe(
-            nan_as_null=nan_as_null, allow_copy=allow_copy
-        )
-
     def abs(self):
         self._validate_dtypes(numeric_only=True)
         return self.__constructor__(query_compiler=self._query_compiler.abs())

modin/pandas/dataframe.py

@@ -2623,6 +2623,35 @@ def __delitem__(self, key):
     __rmod__ = rmod
     __rdiv__ = rdiv
 
+    def __dataframe__(self, nan_as_null: bool = False, allow_copy: bool = True) -> dict:
+        """
+        Get a Modin DataFrame that implements the dataframe exchange protocol.
+
+        See more about the protocol in https://data-apis.org/dataframe-protocol/latest/index.html.
+
+        Parameters
+        ----------
+        nan_as_null : bool, default: False
+            A keyword intended for the consumer to tell the producer
+            to overwrite null values in the data with ``NaN`` (or ``NaT``).
+            This currently has no effect; once support for nullable extension
+            dtypes is added, this value should be propagated to columns.
+        allow_copy : bool, default: True
+            A keyword that defines whether or not the library is allowed
+            to make a copy of the data. For example, copying data would be necessary
+            if a library supports strided buffers, given that this protocol
+            specifies contiguous buffers. Currently, if the flag is set to ``False``
+            and a copy is needed, a ``RuntimeError`` will be raised.
+
+        Returns
+        -------
+        dict
+            A dictionary object following the dataframe protocol specification.
+        """
+        return self._query_compiler.to_dataframe(
+            nan_as_null=nan_as_null, allow_copy=allow_copy
+        )
+
     @property
     def attrs(self):  # noqa: D200
         """

modin/pandas/utils.py

@@ -89,14 +89,14 @@ def from_arrow(at):
 
 def from_dataframe(df):
     """
-    Convert a DataFrame implementing dataframe exchange protocol to a Modin DataFrame.
+    Convert a DataFrame implementing the dataframe exchange protocol to a Modin DataFrame.
 
     See more about the protocol in https://data-apis.org/dataframe-protocol/latest/index.html.
 
     Parameters
     ----------
     df : DataFrame
-        The DataFrame object supporting dataframe exchange protocol.
+        The DataFrame object supporting the dataframe exchange protocol.
 
     Returns
     -------