Source code for flwr_datasets.partitioner.linear_partitioner

# Copyright 2023 Flower Labs GmbH. All Rights Reserved.
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# Licensed under the Apache License, Version 2.0 (the "License");
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#     http://www.apache.org/licenses/LICENSE-2.0
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# ==============================================================================
"""LinearPartitioner class."""


from flwr_datasets.partitioner.id_to_size_fnc_partitioner import IdToSizeFncPartitioner


class LinearPartitioner(IdToSizeFncPartitioner):
    """Partitioner creates partitions of size that are linearly correlated with id.

    The amount of data each client gets is linearly correlated with the partition ID.
    For instance, if the IDs range from 1 to M, client with ID 1 gets 1 unit of data,
    client 2 gets 2 units, and so on, up to client M which gets M units.

    Parameters
    ----------
    num_partitions : int
        The total number of partitions that the data will be divided into.

    Examples
    --------
    >>> from flwr_datasets import FederatedDataset
    >>> from flwr_datasets.partitioner import LinearPartitioner
    >>>
    >>> partitioner = LinearPartitioner(num_partitions=10)
    >>> fds = FederatedDataset(dataset="mnist", partitioners={"train": partitioner})
    >>> partition = fds.load_partition(0)
    """

    def __init__(self, num_partitions: int) -> None:
        super().__init__(
            num_partitions=num_partitions, partition_id_to_size_fn=lambda x: x
        )
        if num_partitions <= 0:
            raise ValueError("The number of partitions must be greater than zero.")