Extra anonymized columns are created during reverse_transform_subset

[npatki]

Environment Details

• RDT version: 1.2.0

Error Description

The reverse_transform_subset method is meant to only reverse transform the columns that are inputted. However, it appears to be creating additional columns from AnonymizedFaker and RegexGenerator transformers.

This is likely happening because these two transformers drop columns on the forward transform.

Steps to reproduce

from rdt import get_demo
from rdt import HyperTransformer

from rdt.transformers.pii import AnonymizedFaker
from rdt.transformers.text import RegexGenerator

# create some data
customers = get_demo()
customers['id'] = ['ID_a', 'ID_b', 'ID_c', 'ID_d', 'ID_e']

# create a config
ht = HyperTransformer()
ht.detect_initial_config(customers)

# credit_card and id are pii and text columns
ht.update_sdtypes({
    'credit_card': 'pii',
    'id': 'text'
})

ht.update_transformers({
    'credit_card': AnonymizedFaker(),
    'id': RegexGenerator(regex_format='id_[a-z]')
})

# transform the data
# this will drop the credit card and id columns
ht.fit(customers)
transformed = ht.transform(customers)

# try to reverse transform only the login column
ht.reverse_transform_subset(transformed[['last_login.value']])

Output

The credit_card and id columns are recreated during reverse_transform_subset even though I only asked to reverse transform the last_login column.

I expect that only the last_login column will be created.

[npatki]

For more info about how to create only anonymized columns, see issue #546