Tuple Policy

A Tuple Policy is needed when using a tuple_sketch in order to specify how the summary values should be created, updated, combined, or intersected. A summary can consist of any python object.

Each implementation must extend the abstract base class TuplePolicy.

class TuplePolicy

An abstract base class for Tuple Policy objects. All custom policies must extend this class.

create_summary(self) → object

Creates a new Summary object

Returns:: a Summary object
Return type:: object

update_summary(self, summary: object, update: object) → object

Applies the relevant policy to update the provided summary with the data in update.

Parameters:

summary (object) – An existing Summary
update (object) – An update to apply to the Summary

Returns:

The updated Summary

Return type:

object

__call__(self, summary: object, update: object) → object

Similar to update_summary but allows a different implementation for set operations (union and intersection)

Parameters:

summary (object) – An existing Summary
update (object) – An update to apply to the Summary

Returns:

The updated Summary

Return type:

object

class AccumulatorPolicy

Bases: TuplePolicy

Implements an accumulatory summary policy, where new values are added to the existing value.

class MinIntPolicy

Bases: TuplePolicy

Implements a MIN rule, where the smallest integer value is always kept.

class MaxIntPolicy

Bases: TuplePolicy

Implements a MAX rule, where the largest integer value is always kept.