APPFL Aggregator

Functionalities

The APPFL Aggregator is used for aggregating one or more client local model(s) to update the global model. Depending on the synchroneity of the FL algorithm, the aggregator can take

• only one client model to update the global model (for asynchronous FL)

• a list of client models to update the global model (for synchronous FL)

• one or a list of client models to update the global model (for asynchronous FL)

The aggregator has the following three main functionalities.

class BaseAggregator:

    @abc.abstractmethod
    def aggregate(self, *args, **kwargs) -> Union[Dict, OrderedDict, Tuple[Union[Dict, OrderedDict], Dict]]:
        """
        Aggregate local model(s) from clients and return the global model
        """
        pass

    @abc.abstractmethod
    def get_parameters(self, **kwargs) -> Union[Dict, OrderedDict, Tuple[Union[Dict, OrderedDict], Dict]]:
        """
        Return global model parameters
        """
        pass

    def set_client_sample_size(self, client_id: Union[str, int], sample_size: int):
        """
        Set the sample size of a client
        """
        if not hasattr(self, "client_sample_size"):
            self.client_sample_size = {}
        self.client_sample_size[client_id] = sample_size

To define a new aggregate, you need to inherit the BaseAggregator class and implement the aggregate and get_parameters methods. You can also define additional methods as needed.

Available Aggregators

All available aggregators are defined in the appfl.algorithm.aggregator module, including:

• FedAvgAggregator: [Synchronous] Federated Averaging (FedAvg) aggregator

• FedAvgMAggregator: [Synchronous] Federated Averaging with Momentum (FedAvgM) aggregator

• FedYogiAggregator: [Synchronous] Federated Yogi (FedYogi) aggregator

• FedAdamAggregator: [Synchronous] Federated Adam (FedAdam) aggregator

• FedAdagradAggregator: [Synchronous] Federated Adagrad (FedAdagrad) aggregator

• FedAsyncAggregator: [Asynchronous] Federated Asynchronous (FedAsync) aggregator

• FedBuffAggregator: [Asynchronous] Federated Buffered (FedBuff) aggregator

• FedCompassAggregator: [Asynchronous] FedCompass aggregator

• ICEADMMAggregator: [Synchronous] ICEADMM aggregator

• IIADMMAggregator: [Synchronous] IIADMM aggregator