get_transformer_tree_yaml fails

[amontanez24]

Environment Details

Please indicate the following details about the environment in which you found the bug:

• RDT version: Any
• Python version: Any
• Operating System: Any

Error Description

The get_transformer_tree_yaml method raises the following error:

RepresenterError: ('cannot represent an object', defaultdict(<class 'dict'>, {'0_int': {'transformer': 'NumericalTransformer', 'outputs': ['0_int.value', '0_int.is_null']}, '1_float': {'transformer': 'NumericalTransformer', 'outputs': ['1_float.value', '1_float.is_null']}, '2_str': {'transformer': 'CategoricalTransformer', 'outputs': ['2_str.value']}, '3_datetime': {'transformer': 'DatetimeTransformer', 'outputs': ['3_datetime.value', '3_datetime.is_null']}}))

Also consider adding a NotFittedError to this method as well.

Steps to reproduce

from rdt import HyperTransformer
from rdt import get_demo

data = get_demo()
ht = HyperTransformer()
ht.fit_transform(data)
ht.get_transformer_tree_yaml()