def from_openfst(cls, s: str, acceptor: bool = True) -> 'Fsa':
'''Create an Fsa from a string in OpenFST format.
The given string `s` consists of lines with the following format:
(1) When it represents an acceptor::
src_state dest_state label score
(2) When it represents a transducer::
src_state dest_state label aux_label score
The line for the final state consists of two fields::
final_state score
Note:
Fields are separated by space(s), tab(s) or both. The `score`
field is a float, while other fields are integers.
There might be multiple final states. Also, OpenFst may omit the score
if it is 0.0.
Args:
s:
The input string. Refer to the above comment for its format.
acceptor:
Optional. If true, interpret the input string as an acceptor;
otherwise, interpret it as a transducer.
'''
arcs, aux_labels = _k2.fsa_from_str(s, acceptor, True)
return Fsa(arcs, aux_labels=aux_labels)
def from_str(cls, s: str) -> 'Fsa':
'''Create an Fsa from a string in the k2 format.
(See also from_openfst).
The given string `s` consists of lines with the following format:
(1) When it represents an acceptor::
src_state dest_state label score
(2) When it represents a transducer::
src_state dest_state label aux_label score
The line for the final state consists of only one field::
final_state
Note:
Fields are separated by space(s), tab(s) or both. The `score`
field is a float, while other fields are integers.
Caution:
The first column has to be non-decreasing.
Caution:
The final state has the largest state number. There is **ONLY**
ONE final state. All arcs that are connected to the final state
have label -1. If there are aux_labels, they are also -1 for
arcs entering the final state.
Args:
s:
The input string. Refer to the above comment for its format.
'''
# Figure out acceptor/transducer for k2 fsa.
acceptor = True
line = s.strip().split('\n', 1)[0]
fields = line.strip().split()
assert len(fields) == 4 or len(fields) == 5
if len(fields) == 5:
acceptor = False
arcs, aux_labels = _k2.fsa_from_str(s, acceptor, False)
ans = Fsa(arcs, aux_labels=aux_labels)
return ans
def from_openfst(cls,
s: str,
acceptor: Optional[bool] = None,
num_aux_labels: Optional[int] = None,
aux_label_names: Optional[List[str]] = None) -> 'Fsa':
'''Create an Fsa from a string in OpenFST format (or a slightly more
general format, if num_aux_labels > 1). See also :func:`from_str`.
The given string `s` consists of lines with the following format::
src_state dest_state label [aux_label1 aux_label2...] [cost]
(the cost defaults to 0.0 if not present).
The line for the final state consists of two fields::
final_state [cost]
Note:
Fields are separated by space(s), tab(s) or both. The `cost`
field is a float, while other fields are integers.
There might be multiple final states. Also, OpenFst may omit the cost
if it is 0.0.
Caution:
We use `cost` here to indicate that its value will be negated so that
we can get `scores`. That is, `score = -1 * cost`.
Note:
At most one of `acceptor`, `num_aux_labels`, and `aux_label_names`
must be supplied; if none are supplied, acceptor format is assumed.
Args:
s:
The input string. Refer to the above comment for its format.
acceptor:
Set to true to denote acceptor format which is num_aux_labels == 0,
or false to denote transducer format (i.e. num_aux_labels == 1
with name 'aux_labels').
num_aux_labels:
The number of auxiliary labels to expect on each line (in addition
to the 'acceptor' label; is 1 for traditional transducers but can be
any non-negative number.
aux_label_names:
If provided, the length of this list dictates the number of
aux_labels. By default the names are 'aux_labels', 'aux_labels2',
'aux_labels3' and so on.
'''
(num_aux_labels, aux_label_names) = \
get_aux_label_info(acceptor, num_aux_labels, aux_label_names)
try:
arcs, aux_labels = _k2.fsa_from_str(s, num_aux_labels, True)
ans = Fsa(arcs)
if num_aux_labels != 0:
for i in range(num_aux_labels):
setattr(ans, aux_label_names[i], aux_labels[i, :])
return ans
except Exception:
raise ValueError(
f'The following is not a valid Fsa in OpenFst format '
f'(with num_aux_labels={num_aux_labels}): {s}')
def from_str(cls,
s: str,
acceptor: Optional[bool] = None,
num_aux_labels: Optional[int] = None,
aux_label_names: Optional[List[str]] = None) -> 'Fsa':
'''Create an Fsa from a string in the k2 or OpenFst format.
(See also :func:`from_openfst`).
The given string `s` consists of lines with the following format::
src_state dest_state label [aux_label1 aux_label2...] [score]
The line for the final state consists of only one field::
final_state
Note:
Fields are separated by space(s), tab(s) or both. The `score`
field is a float, while other fields are integers.
Caution:
The first column has to be non-decreasing.
Caution:
The final state has the largest state number. There is **ONLY**
ONE final state. All arcs that are connected to the final state
have label -1. If there are aux_labels, they are also -1 for
arcs entering the final state.
Note:
At most one of `acceptor`, `num_aux_labels`, and `aux_label_names`
must be supplied; if none are supplied, acceptor format is assumed.
Args:
s:
The input string. Refer to the above comment for its format.
acceptor:
Set to true to denote acceptor format which is num_aux_labels == 0,
or false to denote transducer format (i.e. num_aux_labels == 1
with name 'aux_labels').
num_aux_labels:
The number of auxiliary labels to expect on each line (in addition
to the 'acceptor' label; is 1 for traditional transducers but can be
any non-negative number. The names of the aux_labels default to
'aux_labels' then 'aux_labels2', 'aux_labels3' and so on.
aux_label_names:
If provided, the length of this list dictates the number of
aux_labels and this list dictates their names.
'''
(num_aux_labels, aux_label_names) = \
get_aux_label_info(acceptor, num_aux_labels, aux_label_names)
try:
arcs, aux_labels = _k2.fsa_from_str(s, num_aux_labels, False)
ans = Fsa(arcs)
if aux_labels is not None:
for i in range(aux_labels.shape[0]):
setattr(ans, aux_label_names[i], aux_labels[i, :])
return ans
except Exception:
raise ValueError(f'The following is not a valid Fsa (with '
f'num_aux_labels={num_aux_labels}): {s}')
