Source nested Dictionary filtering based on mapping dict whose all keys are present in Source dictionary in the same structure

dict_filter_using_map_dict.py

def filter_dict(src_dict, mapping_dict):
    for k, v in list(src_dict.items()):
        if k not in mapping_dict:
            del src_dict[k]
        elif isinstance(v, dict) and isinstance(mapping_dict[k], dict):
            src_dict[k] = filter_dict(v, mapping_dict[k])
    return src_dict


# ------------------------ TEST ------------------------

source_dict = {
    'a': 1,
    'b': {
        'd': {
            'f': 4,
            'g': 5
        },
        'e': 3
    },
    'c': 2,
    'x': 'hello'
}

mapping_dict = {
    'a': None,
    'b': {
        'd': {
            'g': None
        },
    },
    'x': None
}

filter_dict(source_dict, mapping_dict)
# {'a': 1, 'x': 'hello', 'b': {'d': {'g': 5}}}