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##################
Privacy Accountant
##################

.. currentmodule:: dp_accounting.privacy_accountant

A `PrivacyAccountant` allows for converting a `DpEvent` or sequence of
`DpEvent`\ s into privacy parameters. One can call `accountant.compose` on each
`DpEvent` we wish to compose, and then use methods like `get_epsilon` and
`get_delta` to get the privacy parameters for the mechanism captured by all
`DpEvent`\ s composed so far.

`dp_accounting` currently supports two types of `PrivacyAccountant`\ s.
:class:`~dp_accounting.pld.PLDAccountant` uses privacy loss distribution (PLD)
accounting, which is generally
tight up to some numerical precision, but can be slow (see the
`supplementary material <https://github.com/google/differential-privacy/blob/main/common_docs/Privacy_Loss_Distributions.pdf>`_
for technical details on PLD accounting). :class:`~dp_accounting.rdp.RdpAccountant` uses
Renyi DP (RDP) accounting, which is faster but not tight in general. Note that not all
`DpEvent`\ s are supported by both accountants, and there may be `DpEvent`\ s
supported by one accountant but not the other.

When initializing a `PrivacyAccountant`, one also specifies the
`NeighboringRelation` which defines how neighboring databases are related.
The default `NeighboringRelation` for both accountants is `ADD_OR_REMOVE_ONE`,
which corresponds to the standard add-or-remove-one definition of DP.

Both accountants have a parameter which allows one to trade off accuracy for
speed. For `RdpAccountant`, this is `orders`, the set of RDP orders which are
tracked and used to compute `epsilon`. For `PLDAccountant`, this is
`value_discretization_interval`, the precision of the discretization of
continuous random variables used in PLD accounting. The default values for these
parameters are fine for most use cases, but one can consider using a denser grid
of `orders` or smaller `value_discretization_interval` if higher accuracy is
needed, or a sparser grid or larger interval if speed is more important.

Classes
-------

.. autoclass:: PrivacyAccountant
   :members:
   :undoc-members:
   :show-inheritance:
   :member-order: bysource

.. autoclass:: NeighboringRelation
   :members:
   :undoc-members:

.. autoclass:: dp_accounting.rdp.RdpAccountant
   :members:
   :undoc-members:
   :show-inheritance:

.. autoclass:: dp_accounting.pld.PLDAccountant
   :members:
   :undoc-members:
   :show-inheritance:

Exceptions
----------

.. autoexception:: UnsupportedEventError
   :members: