def score_ll(self, sequences):
r"""log of the likelihood of sequences with respect to the model
Parameters
----------
sequences : list of array-like
List of sequences, or a single sequence. Each sequence should be a
1D iterable of state labels. Labels can be integers, strings, or
other orderable objects.
Returns
-------
loglikelihood : float
The natural log of the likelihood, computed as
:math:`\sum_{ij} C_{ij} \log(P_{ij})`
where C is a matrix of counts computed from the input sequences.
"""
counts, mapping = _transition_counts(sequences)
if not set(self.mapping_.keys()).issuperset(mapping.keys()):
return -np.inf
inverse_mapping = {v: k for k, v in mapping.items()}
# maps indices in counts to indices in transmat
m2 = _dict_compose(inverse_mapping, self.mapping_)
indices = [e[1] for e in sorted(m2.items())]
transmat_slice = self.transmat_[np.ix_(indices, indices)]
return np.nansum(np.log(transmat_slice) * counts)
def fit(self, sequences, y=None):
sequences = list_of_1d(sequences)
raw_counts, mapping = _transition_counts(sequences, self.lag_time)
if self.ergodic_cutoff >= 1:
self.countsmat_, mapping2 = _strongly_connected_subgraph(
raw_counts, self.ergodic_cutoff, self.verbose)
self.mapping_ = _dict_compose(mapping, mapping2)
else:
self.countsmat_ = raw_counts
self.mapping_ = mapping
self.n_states_ = self.countsmat_.shape[0]
fit_method_map = {
True: self._fit_reversible,
False: self._fit_non_reversible}
try:
fit_method = fit_method_map[self.reversible]
self.all_transmats_ = fit_method(self.countsmat_)
except KeyError:
raise ValueError('reversible_type must be one of %s: %s' % (
', '.join(fit_method_map.keys()), self.reversible_type))
return self
def fit(self, sequences, y=None):
"""Estimate model parameters.
Parameters
----------
sequences : list of array-like
List of sequences, or a single sequence. Each sequence should be a
1D iterable of state labels. Labels can be integers, strings, or
other orderable objects.
Returns
-------
self
Notes
-----
`None` and `NaN` are recognized immediately as invalid labels.
Therefore, transition counts from or to a sequence item which is NaN or
None will not be counted. The mapping_ attribute will not include the
NaN or None.
"""
sequences = list_of_1d(sequences)
# step 1. count the number of transitions
raw_counts, mapping = _transition_counts(sequences, self.lag_time)
if self.ergodic_cutoff >= 1:
# step 2. restrict the counts to the maximal strongly ergodic
# subgraph
self.countsmat_, mapping2 = _strongly_connected_subgraph(raw_counts, self.ergodic_cutoff, self.verbose)
self.mapping_ = _dict_compose(mapping, mapping2)
else:
# no ergodic trimming.
self.countsmat_ = raw_counts
self.mapping_ = mapping
self.n_states_ = self.countsmat_.shape[0]
# use a dict like a switch statement: dispatch to different
# transition matrix estimators depending on the value of
# self.reversible_type
fit_method_map = {"mle": self._fit_mle, "transpose": self._fit_transpose, "none": self._fit_asymetric}
try:
# pull out the appropriate method
fit_method = fit_method_map[str(self.reversible_type).lower()]
# step 3. estimate transition matrix
self.transmat_, self.populations_ = fit_method(self.countsmat_)
except KeyError:
raise ValueError(
"reversible_type must be one of %s: %s" % (", ".join(fit_method_map.keys()), self.reversible_type)
)
self._is_dirty = True
return self
