|---| | [ View source on GitHub](https://github.com/tensorflow/federated/blob/v0.87.0 Version 2.0, January 2004 Licensed under the Apache License, Version 2.0 (the) | Aggregation factory for weighted mean. Inherits From: [`WeightedAggregationFactory`](https://www.tensorflow.org/federated/api_docs/python/tff/aggregators/WeightedAggregationFactory) tff.aggregators.MeanFactory( value_sum_factory: Optional[https://www.tensorflow.org/federated/api_docs/python/tff/aggregators/UnweightedAggregationFactory] = None, weight_sum_factory: Optional[https://www.tensorflow.org/federated/api_docs/python/tff/aggregators/UnweightedAggregationFactory] = None, no_nan_division: bool = False ) ### Used in the notebooks | Used in the tutorials | |---| | - [Tuning recommended aggregations for learning](https://www.tensorflow.org/federated/tutorials/tuning_recommended_aggregators) - [Composing Learning Algorithms](https://www.tensorflow.org/federated/tutorials/composing_learning_algorithms) | The created [`tff.templates.AggregationProcess`](https://www.tensorflow.org/federated/api_docs/python/tff/templates/AggregationProcess) computes the weighted mean of values placed at `CLIENTS`, and outputs the mean placed at `SERVER`. The input arguments of the `next` attribute of the process returned by `create` are ``, where `weight` is a scalar broadcasted to the structure of `value`, and the weighted mean refers to the expression `sum(value * weight) / sum(weight)`. The implementation is parameterized by two inner aggregation factories responsible for the summations above, with the following high-level steps. - Multiplication of `value` and `weight` at `CLIENTS`. - Delegation to inner `value_sum_factory` and `weight_sum_factory` to realize the sum of weighted values and weights. - Division of summed weighted values and summed weights at `SERVER`. Note that the the division at `SERVER` can protect against division by 0, as specified by `no_nan_division` constructor argument. The `state` is the composed `state` of the aggregation processes created by the two inner aggregation factories. The same holds for `measurements`.


| ## Args || |---|---| | `value_sum_factory` | An optional [`tff.aggregators.UnweightedAggregationFactory`](https://www.tensorflow.org/federated/api_docs/python/tff/aggregators/UnweightedAggregationFactory) responsible for summation of weighted values. If not specified, [`tff.aggregators.SumFactory`](https://www.tensorflow.org/federated/api_docs/python/tff/aggregators/SumFactory) is used. | | `weight_sum_factory` | An optional [`tff.aggregators.UnweightedAggregationFactory`](https://www.tensorflow.org/federated/api_docs/python/tff/aggregators/UnweightedAggregationFactory) responsible for summation of weights. If not specified, [`tff.aggregators.SumFactory`](https://www.tensorflow.org/federated/api_docs/python/tff/aggregators/SumFactory) is used. | | `no_nan_division` | A bool. If True, the computed mean is 0 if sum of weights is equal to 0. |



| ## Raises || |---|---| | `TypeError` | If provided `value_sum_factory` or `weight_sum_factory` is not an instance of [`tff.aggregators.UnweightedAggregationFactory`](https://www.tensorflow.org/federated/api_docs/python/tff/aggregators/UnweightedAggregationFactory). |
## Methods ### `create` [View source](https://github.com/tensorflow/federated/blob/v0.87.0 Version 2.0, January 2004 Licensed under the Apache License, Version 2.0 (the) create( value_type: factory.ValueType, weight_type: factory.ValueType ) -> https://www.tensorflow.org/federated/api_docs/python/tff/templates/AggregationProcess Creates a `tff.aggregators.AggregationProcess` with weights. The provided `value_type` and `weight_type` are non-federated [`tff.Type`](https://www.tensorflow.org/federated/api_docs/python/tff/types/Type)s. That is, neither is a [`tff.FederatedType`](https://www.tensorflow.org/federated/api_docs/python/tff/types/FederatedType). The returned `tff.aggregators.AggregationProcess` will be created for aggregation of pairs of values matching `value_type` and `weight_type` placed at [`tff.CLIENTS`](https://www.tensorflow.org/federated/api_docs/python/tff#CLIENTS). That is, its `next` method will expect type ``, where `S` is the unplaced return type of its `initialize` method.


| Args || |---|---| | `value_type` | A non-federated [`tff.Type`](https://www.tensorflow.org/federated/api_docs/python/tff/types/Type). | | `weight_type` | A non-federated [`tff.Type`](https://www.tensorflow.org/federated/api_docs/python/tff/types/Type). |



| Returns || |---|---| | A [`tff.templates.AggregationProcess`](https://www.tensorflow.org/federated/api_docs/python/tff/templates/AggregationProcess). ||