Add even vertical partitioner

datasets/flwr_datasets/partitioner/__init__.py

@@ -29,6 +29,7 @@
 from .shard_partitioner import ShardPartitioner
 from .size_partitioner import SizePartitioner
 from .square_partitioner import SquarePartitioner
+from .vertical_even_partitioner import VerticalEvenPartitioner
 
 __all__ = [
     "DirichletPartitioner",
@@ -45,4 +46,5 @@
     "ShardPartitioner",
     "SizePartitioner",
     "SquarePartitioner",
+    "VerticalEvenPartitioner",
 ]

datasets/flwr_datasets/partitioner/vertical_even_partitioner.py

@@ -0,0 +1,226 @@
+# Copyright 2024 Flower Labs GmbH. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under 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.
+# ==============================================================================
+"""VerticalEvenPartitioner class."""
+# flake8: noqa: E501
+from typing import Literal, Optional, Union
+
+import numpy as np
+
+import datasets
+from flwr_datasets.partitioner.partitioner import Partitioner
+from flwr_datasets.partitioner.vertical_partitioner_utils import (
+    _add_active_party_columns,
+    _list_split,
+)
+
+
+class VerticalEvenPartitioner(Partitioner):
+    """Partitioner that splits features (columns) evenly into vertical partitions.
+
+    Enables selection of "active party" column(s) and palcement into
+    a specific partition or creation of a new partition just for it.
+    Also enables droping columns and sharing specified columns across
+    all partitions.
+
+    The number and nature of partitions can be defined in various ways:
+    - By specifying a simple integer for even splitting.
+    - By providing ratios or absolute counts for each partition.
+    - By explicitly listing the columns for each partition.
+    (see `column_distribution` and `mode` parameters for more details)
+
+    Parameters
+    ----------
+    num_partitions : int
+        Number of partitions to create.
+    active_party_columns : Optional[list[str]]
+        Columns associated with the "active party" (which can be the server).
+    active_party_columns_mode : Union[Literal[["add_to_first", "add_to_last", "create_as_first", "create_as_last", "add_to_all"], int]
+        Determines how to assign the active party columns:
+        - "add_to_first": Append active party columns to the first partition.
+        - "add_to_last": Append active party columns to the last partition.
+        - int: Append active party columns to the specified partition index.
+        - "create_as_first": Create a new partition at the start containing only
+            these columns.
+        - "create_as_last": Create a new partition at the end containing only
+            these columns.
+        - "add_to_all": Append active party columns to all partitions.
+    drop_columns : Optional[list[str]]
+        Columns to remove entirely from the dataset before partitioning.
+    shared_columns : Optional[list[str]]
+        Columns to duplicate into every partition after initial partitioning.
+    shuffle : bool
+        Whether to shuffle the order of columns before partitioning.
+    seed : Optional[int]
+        Random seed for shuffling columns. Has no effect if `shuffle=False`.
+
+    Examples
+    --------
+    >>> partitioner = VerticalEvenPartitioner(
+    ...     num_partitions=3,
+    ...     active_party_columns=["income"],
+    ...     active_party_columns_mode="add_to_last",
+    ...     shuffle=True,
+    ...     seed=42
+    ... )
+    >>> fds = FederatedDataset(
+    ...     dataset="scikit-learn/adult-census-income",
+    ...     partitioners={"train": partitioner}
+    ... )
+    >>> partitions = [fds.load_partition(i) for i in range(partitioner.num_partitions)]
+    >>> print([partition.column_names for partition in partitions])
+    """
+
+    def __init__(
+        self,
+        num_partitions: int,
+        active_party_columns: Optional[list[str]] = None,
+        active_party_columns_mode: Union[
+            Literal[
+                "add_to_first",
+                "add_to_last",
+                "create_as_first",
+                "create_as_last",
+                "add_to_all",
+            ],
+            int,
+        ] = "add_to_last",
+        drop_columns: Optional[list[str]] = None,
+        shared_columns: Optional[list[str]] = None,
+        shuffle: bool = True,
+        seed: Optional[int] = 42,
+    ) -> None:
+        super().__init__()
+
+        self._num_partitions = num_partitions
+        self._active_party_columns = active_party_columns or []
+        self._active_party_columns_mode = active_party_columns_mode
+        self._drop_columns = drop_columns or []
+        self._shared_columns = shared_columns or []
+        self._shuffle = shuffle
+        self._seed = seed
+        self._rng = np.random.default_rng(seed=self._seed)
+
+        self._partition_columns: Optional[list[list[str]]] = None
+        self._partitions_determined = False
+
+        self._validate_parameters_in_init()
+
+    def _determine_partitions_if_needed(self) -> None:
+        if self._partitions_determined:
+            return
+
+        if self.dataset is None:
+            raise ValueError("No dataset is set for this partitioner.")
+
+        all_columns = list(self.dataset.column_names)
+        self._validate_parameters_while_partitioning(
+            all_columns, self._shared_columns, self._active_party_columns
+        )
+        columns = [column for column in all_columns if column not in self._drop_columns]
+        columns = [column for column in columns if column not in self._shared_columns]
+        columns = [
+            column for column in columns if column not in self._active_party_columns
+        ]
+
+        if self._shuffle:
+            self._rng.shuffle(columns)
+        partition_columns = _list_split(columns, self._num_partitions)
+        partition_columns = _add_active_party_columns(
+            self._active_party_columns,
+            self._active_party_columns_mode,
+            partition_columns,
+        )
+
+        # Add shared columns to all partitions
+        for partition in partition_columns:
+            for column in self._shared_columns:
+                partition.append(column)
+
+        self._partition_columns = partition_columns
+        self._partitions_determined = True
+
+    def load_partition(self, partition_id: int) -> datasets.Dataset:
+        """Load a partition based on the partition index.
+
+        Parameters
+        ----------
+        partition_id : int
+            The index that corresponds to the requested partition.
+
+        Returns
+        -------
+        dataset_partition : Dataset
+            Single partition of a dataset.
+        """
+        self._determine_partitions_if_needed()
+        assert self._partition_columns is not None
+        if partition_id < 0 or partition_id >= len(self._partition_columns):
+            raise ValueError(f"Invalid partition_id {partition_id}.")
+        columns = self._partition_columns[partition_id]
+        return self.dataset.select_columns(columns)
+
+    @property
+    def num_partitions(self) -> int:
+        """Number of partitions."""
+        self._determine_partitions_if_needed()
+        assert self._partition_columns is not None
+        return len(self._partition_columns)
+
+    def _validate_parameters_in_init(self) -> None:
+        if self._num_partitions < 1:
+            raise ValueError("column_distribution as int must be >= 1.")
+
+        # Validate columns lists
+        for parameter_name, parameter_list in [
+            ("drop_columns", self._drop_columns),
+            ("shared_columns", self._shared_columns),
+            ("active_party_columns", self._active_party_columns),
+        ]:
+            if not all(isinstance(column, str) for column in parameter_list):
+                raise ValueError(f"All entries in {parameter_name} must be strings.")
+
+        valid_modes = {
+            "add_to_first",
+            "add_to_last",
+            "create_as_first",
+            "create_as_last",
+            "add_to_all",
+        }
+        if not (
+            isinstance(self._active_party_columns_mode, int)
+            or self._active_party_columns_mode in valid_modes
+        ):
+            raise ValueError(
+                "active_party_columns_mode must be an int or one of "
+                "'add_to_first', 'add_to_last', 'create_as_first', 'create_as_last', "
+                "'add_to_all'."
+            )
+
+    def _validate_parameters_while_partitioning(
+        self,
+        all_columns: list[str],
+        shared_columns: list[str],
+        active_party_columns: list[str],
+    ) -> None:
+        # Shared columns existance check
+        for column in shared_columns:
+            if column not in all_columns:
+                raise ValueError(f"Shared column '{column}' not found in the dataset.")
+        # Active party columns existence check
+        for column in active_party_columns:
+            if column not in all_columns:
+                raise ValueError(
+                    f"Active party column '{column}' not found in the dataset."
+                )