def remove_epsilon(fsa: Fsa) -> Fsa:
'''Remove epsilons (symbol zero) in the input Fsa.
Caution:
It only works on for CPU and doesn't support autograd.
Args:
fsa:
The input FSA. It can be either a single FSA or an FsaVec.
Must be top-sorted.
Returns:
The result Fsa, it's equivalent to the input ``fsa`` under
tropical semiring but will be epsilon-free.
It will be the same as the input ``fsa`` if the input
``fsa`` is epsilon-free. Otherwise, a new epsilon-free fsa
is returned and the input ``fsa`` is NOT modified.
'''
properties = getattr(fsa, 'properties', None)
if properties is not None and properties & fsa_properties.EPSILON_FREE != 0:
return fsa
ragged_arc, arc_derivs = _k2.remove_epsilon(fsa.arcs)
aux_labels = None
if hasattr(fsa, 'aux_labels'):
aux_labels = _k2.simple_ragged_index_select(fsa.aux_labels, arc_derivs)
out_fsa = Fsa(ragged_arc, aux_labels)
for name, value in fsa.named_non_tensor_attr():
setattr(out_fsa, name, value)
return out_fsa
def determinize(fsa: Fsa) -> Fsa:
'''Determinize the input Fsa.
Caution:
It only works on for CPU and doesn't support autograd.
Args:
fsa:
The input FSA. It can be either a single FSA or an FsaVec.
Must be connected. It's also expected to be epsilon-free,
but this is not checked; in any case,
epsilon will be treated as a normal symbol.
Returns:
The result Fsa, it's equivalent to the input ``fsa`` under
tropical semiring but will be deterministic.
It will be the same as the input ``fsa`` if the input
``fsa`` has property kFsaPropertiesArcSortedAndDeterministic.
Otherwise, a new deterministic fsa is returned and the
input ``fsa`` is NOT modified.
'''
properties = getattr(fsa, 'properties', None)
if properties is not None \
and properties & fsa_properties.ARC_SORTED_AND_DETERMINISTIC != 0: # noqa
return fsa
ragged_arc, arc_derivs = _k2.determinize(fsa.arcs)
aux_labels = None
if hasattr(fsa, 'aux_labels'):
aux_labels = _k2.simple_ragged_index_select(fsa.aux_labels, arc_derivs)
out_fsa = Fsa(ragged_arc, aux_labels)
for name, value in fsa.named_non_tensor_attr():
setattr(out_fsa, name, value)
return out_fsa