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tf_privacy.TreeRangeSumQuery

Implements dp_query for accurate range queries using tree aggregation.

Inherits From: SumAggregationDPQuery, DPQuery

Implements a variant of the tree aggregation protocol from. "Is interaction necessary for distributed private learning?. Adam Smith, Abhradeep Thakurta, Jalaj Upadhyay." Builds a tree on top of the input record and adds noise to the tree for differential privacy. Any range query can be decomposed into the sum of O(log(n)) nodes in the tree compared to O(n) when using a histogram. Improves efficiency and reduces noise scale.

inner_query The inner DPQuery that adds noise to the tree.
arity The branching factor of the tree (i.e. the number of children each internal node has). Defaults to 2.

Child Classes

class GlobalState

Methods

accumulate_preprocessed_record

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Implements tensorflow_privacy.DPQuery.accumulate_preprocessed_record.

accumulate_record

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Accumulates a single record into the sample state.

This is a helper method that simply delegates to preprocess_record and accumulate_preprocessed_record for the common case when both of those functions run on a single device. Typically this will be a simple sum.

Args
params The parameters for the sample. In standard DP-SGD training, the clipping norm for the sample's microbatch gradients (i.e., a maximum norm magnitude to which each gradient is clipped)
sample_state The current sample state. In standard DP-SGD training, the accumulated sum of previous clipped microbatch gradients.
record The record to accumulate. In standard DP-SGD training, the gradient computed for the examples in one microbatch, which may be the gradient for just one example (for size 1 microbatches).

Returns
The updated sample state. In standard DP-SGD training, the set of previous microbatch gradients with the addition of the record argument.

build_central_gaussian_query

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Returns TreeRangeSumQuery with central Gaussian noise.

Args
l2_norm_clip Each record should be clipped so that it has L2 norm at most l2_norm_clip.
stddev Stddev of the central Gaussian noise.
arity The branching factor of the tree (i.e. the number of children each internal node has). Defaults to 2.

build_distributed_discrete_gaussian_query

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Returns TreeRangeSumQuery with central Gaussian noise.

Args
l2_norm_bound Each record should be clipped so that it has L2 norm at most l2_norm_bound.
local_stddev Scale/stddev of the local discrete Gaussian noise.
arity The branching factor of the tree (i.e. the number of children each internal node has). Defaults to 2.

derive_metrics

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Derives metric information from the current global state.

Any metrics returned should be derived only from privatized quantities.

Args
global_state The global state from which to derive metrics.

Returns
A collections.OrderedDict mapping string metric names to tensor values.

derive_sample_params

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Implements tensorflow_privacy.DPQuery.derive_sample_params.

get_noised_result

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Implements tensorflow_privacy.DPQuery.get_noised_result.

This function re-constructs the tf.RaggedTensor from the flattened tree output by preprocess_records.

Args
sample_state A tf.Tensor for the flattened tree.
global_state The global state of the protocol.

Returns
A tf.RaggedTensor representing the tree.

initial_global_state

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Implements tensorflow_privacy.DPQuery.initial_global_state.

initial_sample_state

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Implements tensorflow_privacy.DPQuery.initial_sample_state.

merge_sample_states

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Implements tensorflow_privacy.DPQuery.merge_sample_states.

preprocess_record

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Implements tensorflow_privacy.DPQuery.preprocess_record.

This method builds the tree, flattens it and applies inner_query.preprocess_record to the flattened tree.

Args
params Hyper-parameters for preprocessing record.
record A histogram representing the leaf nodes of the tree.

Returns
A tf.Tensor representing the flattened version of the preprocessed tree.