'Return a matrix of transition log probabilities.'

def _transitions_matrix(self):

    trans_iter = (self._transitions[sj].logprob(si) for sj in self._states for si in self._states)
    transitions_logprob = np.fromiter(trans_iter, dtype=np.float64)
    N = len(self._states)
    return transitions_logprob.reshape((N, N)).T
