An UnweightedAggregationFactory for reservoir sampling values.

Inherits From: UnweightedAggregationFactory

The created tff.templates.AggregationProcess samples values placed at CLIENTS, and outputs the sample placed at SERVER.

The process has empty state. The measurements of this factory counts the number of non-finite (NaN or Inf values) leaves in the client values before sampling. Specifically, the returned measurements has the same structure as the client value, and every leaf node is a tf.int64 scalar tensor counting the number of clients having non-finite value in that leaf.

For example, suppose we are aggregating from three clients:

  client_value_1 = collections.OrderedDict(a=[1.0, 2.0], b=[1.0, np.nan])
  client_value_2 = collections.OrderedDict(a=[np.nan, np.inf], b=[1.0, 2.0])
  client_value_3 = collections.OrderedDict(a=[1.0, 2.0], b=[np.inf, np.nan])

Then measurements will be:

  collections.OrderedDict(a=tf.constant(1, dtype=int64),
                          b=tf.constant(2, dtype=int64)

For more about reservoir sampling see

sample_size An integer specifying the number of clients sampled (by reservoir sampling algorithm). Values from the sampled clients are collected at the server (see the class documentation for details).
return_sampling_metadata If True, the result property in the returned tff.templates.MeasuredProcessOutput object contains a dictionary of sampled values and other sampling metadata (such as random values generated during reservoir sampling). Otherwise, it only contains the sampled values.

TypeError If any argument type mismatches.
ValueError If sample_size is not positive.



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Creates a tff.aggregators.AggregationProcess without weights.

The provided value_type is a non-federated tff.Type, that is, not a tff.FederatedType.

The returned tff.aggregators.AggregationProcess will be created for aggregation of values matching value_type placed at tff.CLIENTS. That is, its next method will expect type <S@SERVER, {value_type}@CLIENTS>, where S is the unplaced return type of its initialize method.

value_type A non-federated tff.Type.

A tff.templates.AggregationProcess.