❖ SelfReferentialHierarchy

❖ SDV Enterprise Bundle. This feature is available as part of the CAG Bundle, an optional add-on to SDV Enterprise. For more information, please visit the CAG Bundle page.

Use the SelfReferentialHierarchy constraint when you have a column in the table that references the primary key column of the same table (aka a self-reference); and the self-references are not allowed to have any cycles.

In this example, the "Manger ID" column references the primary key, "Employee ID" that is in the same table. This self-reference is not allowed to have cycles, meaning that the manager/employee relationships forms a strict reporting chain all the way up to the CEO. (If person A manages person B, then B cannot manage person A.)

Constraint API

This functionality is in Beta. At this time, select SDV Enterprise users have been invited to use this feature.

Create a SelfReferentialHierarchy constraint.

Parameters:

• (required) table_name: A string with the name of the table that contains the self-reference

• (required) primary_key: A string with the name of the primary key column in the table

• (required) foreign_key: A string with the name of the foreign key column in the same table that references the primary key

• scaling_method: A string with the name of the method, used when scaling up the synthetic data

  • (default) 'branch': Keep the original depth of the hierarchy but add more branches to it. In our example above, this would add more reports for a given manager.

  • 'depth': Add to the depth of the self-references. In our example above, this would create new levels of managers, increasing the length of the reporting chain to the CEO.

from sdv.cag import SelfReferentialHierarchy

my_constraint = SelfReferentialHierarchy(
    table_name='Employees',
    primary_key='Employee ID',
    foreign_key='Manager ID')

Make sure that all the table and columns in you provide are in your Metadata, and have a primary key associated with them. Note that you cannot supply a self-reference relationship in the metadata right now, so the relationships section of your Metadata can be blank.

Usage

Apply the constraint to any SDV synthesizer. Then fit and sample as usual.

synthesizer = HSASynthesizer(metadata)
synthesizer.add_cag([my_constraint])

synthesizer.fit(data)
synthetic_data = synthesizer.sample()