forward_viterbi.cpp

来自「The algorm of viterbi. You talk to your 」· C++ 代码 · 共 33 行

def forward_viterbi(y, X, sp, tp, ep):
   T = {}
   for state in X:
       ##          prob.      V. path  V. prob.
       T[state] = (sp[state], [state], sp[state])
   for output in y:
       U = {}
       for next_state in X:
           total = 0
           argmax = None
           valmax = 0
           for source_state in X:
               (prob, v_path, v_prob) = T[source_state]
               p = ep[source_state][output] * tp[source_state][next_state]
               prob *= p
               v_prob *= p
               total += prob
               if v_prob > valmax:
                   argmax = v_path + [next_state]
                   valmax = v_prob
           U[next_state] = (total, argmax, valmax)
       T = U
   ## apply sum/max to the final states:
   total = 0
   argmax = None
   valmax = 0
   for state in X:
       (prob, v_path, v_prob) = T[state]
       total += prob
       if v_prob > valmax:
           argmax = v_path
           valmax = v_prob
   return (total, argmax, valmax)