def __post_init__(self):
"""Validate inputs."""
assert_(
0 < self.delta < 1.0,
"Delta must be a non-zero probability.",
)
assert_(
((self.dataset is None) != (self.sample_generator is None)),
"Only one between dataset and sample generator must be specified.",
)
def __post_init__(self):
"""Post-initialization checks."""
assert_(self.nb_states > 0,
"Number of states must be greater than zero.")
assert_(self.alphabet_size > 0,
"Alphabet size must be greater than zero.")
_check_transitions_are_legal(self.transition_dict, self.nb_states,
self.alphabet_size)
_check_ergodicity(self.transition_dict, self.nb_states,
self.final_state)
def get_successor(self, state: State, character: Character) -> State:
"""
Get the successor state.
:param state: the starting state.
:param character: the read symbol.
:return: the new state.
"""
_check_is_legal_state(state, self.nb_states)
_check_is_legal_character(character, self.alphabet_size)
next_transitions = self.transition_dict.get(state, {})
assert_(
character in next_transitions,
f"Cannot read character {state} from state {character}.",
)
next_state, _probability = next_transitions[character]
return next_state
def _check_ergodicity(
transitions: TransitionFunctionDict, nb_states: int, final_state: int
):
"""Check ergodicity of a transition function."""
# reachability
current: Set[State] = set()
next_ = {final_state}
while current != next_:
current = copy(next_)
for start, out_transitions in transitions.items():
for _char, (end, probability) in out_transitions.items():
if end in current and probability > 0.0:
next_.add(start)
nonreachability_set = set(range(nb_states)).difference(current)
assert_(
len(nonreachability_set) == 0,
f"The following states cannot reach the final state: {nonreachability_set}",
)
def _check_transitions_are_legal(
transitions: TransitionFunctionDict, nb_states: int, alphabet_size: int
):
"""Check states and characters are legal."""
for state, char2state in transitions.items():
_check_is_legal_state(state, nb_states)
sum_outgoing_probabilities = 0.0
for character, (next_state, probability) in char2state.items():
_check_is_legal_character(character, alphabet_size)
assert_(0.0 <= probability <= 1.0, f"'{probability}' is not a probability.")
sum_outgoing_probabilities += probability
_check_is_legal_character(character, alphabet_size)
_check_is_legal_state_or_final(next_state, nb_states)
_check_final_symbol_and_final_state(character, next_state)
rounded_sum = round(sum_outgoing_probabilities, ROUND_PRECISION)
assert_(
rounded_sum == 1.0,
f"Outgoing probability from state {state} do not sum to 1: {rounded_sum}",
)
def __post_init__(self):
"""Validate inputs."""
assert_(
self.delta_1 + self.delta_2 <= 1.0,
"Sum of two probabilities cannot be greater than 1.",
)
def _check_is_legal_state_or_final(state: State, nb_states: int) -> None:
"""Check that a state is legal, including final states."""
assert_(
0 <= state < nb_states or state == FINAL_STATE,
"Provided state is not in the set of states, nor is a final state.",
)
def _check_is_legal_state(state: State, nb_states: int) -> None:
"""Check that a state is legal."""
assert_(0 <= state < nb_states, "Provided state is not in the set of states.")
def _check_is_legal_word(w: Word, alphabet_size) -> None:
"""Check that a word is consistent with the alphabet."""
assert_(
all(0 <= c < alphabet_size for c in w[:-1]),
"Provided word is not in the alphabet.",
)
def _check_is_legal_character(character: Character, alphabet_size) -> None:
"""Check that a character is in the alphabet."""
assert_(
FINAL_SYMBOL <= character < alphabet_size,
"Provided character is not in the alphabet.",
)
