Bug in the inverse preprocessing of the Adult dataset

[stighellemans]

Describe the bug
When inverse preprocessing, there exists a bug where only the continuous columns will be kept. All the categorical columns will be thrown away.

To Reproduce
adult = Adult(test_path="local_path_to_test_adult.csv",
train_path="local_path_to_train_adult.csv",
preprocess=True,
)

adult_test_data = adult.inverse_preprocess(adult.test_data)

--> This will give only the continuous columns.

Expected behavior
Normally, all columns, including the categorical ones, should be available after inverse preprocessing.

Environment

• Python version: 3.8
• OS: MacOS