def voi(cid: CID, decision: str, variable: str) -> float:
# TODO test this method
new = cid.copy()
new.add_edge(variable, decision)
new.impute_optimal_policy()
ev1: float = new.expected_utility({})
new = cid.copy()
new.remove_edge(variable, decision)
new.impute_optimal_policy()
ev2: float = new.expected_utility({})
return ev1 - ev2
def _add_sufficient_recall(cid: CID, dec1: str, dec2: str,
utility_node: str) -> None:
"""Add edges to a cid until `dec2` has sufficient recall of `dec1` (to optimize utility)
this is done by adding edges from non-collider nodes until recall is adequate
"""
if dec2 in cid._get_ancestors_of(dec1):
raise ValueError('{} is an ancestor of {}'.format(dec2, dec1))
cid2 = cid.copy()
cid2.add_edge('pi', dec1)
while cid2.is_active_trail('pi',
utility_node,
observed=cid.get_parents(dec2) + [dec2]):
path = find_active_path(cid2, 'pi', utility_node,
cid.get_parents(dec2) + [dec2])
if path is None:
raise Exception(
"couldn't find path even though there should be an active trail"
)
while True:
i = random.randrange(1, len(path) - 1)
# print('consider {}--{}--{}'.format(path[i-1], path[i], path[i+1]),end='')
collider = ((path[i - 1], path[i]) in cid2.edges) and (
(path[i + 1], path[i]) in cid2.edges)
if not collider:
if dec2 not in cid2._get_ancestors_of(path[i]):
# print('add {}->{}'.format(path[i], dec2), end=' ')
cid.add_edge(path[i], dec2)
cid2.add_edge(path[i], dec2)
break
