def update(pi, A, B, alpha, beta, gamma, ksi, o):
print('start updating......')
T = len(o)
for i in range(4):
pi[i] = gamma[0][i]
s1 = [0 for x in range(T - 1)]
s2 = [0 for x in range(T - 1)]
for i in range(4):
for j in range(4):
for t in range(T - 1):
s1[t] = ksi[t][i][j]
s2[t] = gamma[t][i]
A[i][j] = Tool.log_sum(s1) - Tool.log_sum(s2)
s1 = [0 for x in range(T)]
s2 = [0 for x in range(T)]
for i in range(4):
for k in range(65536):
if k % 5000 == 0:
print(i, k)
valid = 0
for t in range(T):
if ord(o[t]) == k:
s1[valid] = gamma[t][i]
valid += 1
s2[t] = gamma[t][i]
if valid == 0:
B[i][k] = -Tool.log_sum(s2)
else:
B[i][k] = Tool.log_sum(s1[:valid]) - Tool.log_sum(s2)
print('baum-welch algorithm have been finished......')
def inite():
pi = [random.random() for x in range(4)]
Tool.log_normalize(pi)
A = [[random.random() for y in range(4)] for x in range(4)]
A[0][0] = A[0][3] = A[1][0] = A[1][3] = A[2][1] = A[2][2] = A[3][1] = A[3][
2] = 0
B = [[random.random() for y in range(65536)] for x in range(4)]
for i in range(4):
A[i] = Tool.log_normalize(A[i])
B[i] = Tool.log_normalize(B[i])
return pi, A, B
def cal_gamma(alpha, beta, gamma):
print('start calculating gamma......')
for t in range(len(alpha)):
for i in range(4):
gamma[t][i] = alpha[t][i] + beta[t][i]
s = Tool.log_sum(gamma[t])
for i in range(4):
gamma[t][i] -= s
print('The calculation of gamma have been finished......')
def baum_welch(pi, A, B, filename):
f = open(filename, encoding='UTF-8')
sentences = f.read()[3:]
f.close()
T = len(sentences) # 观测序列
alpha = [[0 for i in range(4)] for t in range(T)]
beta = [[0 for i in range(4)] for t in range(T)]
gamma = [[0 for i in range(4)] for t in range(T)]
ksi = [[[0 for j in range(4)] for i in range(4)] for t in range(T - 1)]
for time in range(1000):
print('Time : ', time)
sentence = sentences
cal_alpha(pi, A, B, sentence, alpha)
cal_beta(pi, A, B, sentence, beta)
cal_gamma(alpha, beta, gamma)
cal_kesi(alpha, beta, A, B, sentence, ksi)
update(pi, A, B, alpha, beta, gamma, ksi, sentence)
Tool.saveParameter(pi, A, B, 'unsupervisedParam')
print('Save matrix successfully!')
def cal_alpha(pi, A, B, o, alpha):
print('start calculating alpha......')
for i in range(4):
alpha[0][i] = pi[i] + B[i][ord(o[0])]
T = len(o)
temp = [0 for i in range(4)]
del i
for t in range(1, T):
for i in range(4):
for j in range(4):
temp[j] = (alpha[t - 1][j] + A[j][i])
alpha[t][i] = Tool.log_sum(temp)
alpha[t][i] += B[i][ord(o[t])]
print('The calculation of alpha have been finished......')
def cal_beta(pi, A, B, o, beta):
print('start calculating beta......')
T = len(o)
for i in range(4):
beta[T - 1][i] = 1
temp = [0 for i in range(4)]
del i
for t in range(T - 2, -1, -1):
for i in range(4):
beta[t][i] = 0
for j in range(4):
temp[j] = A[i][j] + B[j][ord(o[t + 1])] + beta[t + 1][j]
beta[t][i] += Tool.log_sum(temp)
print('The calculation of beta have been finished......')
def cal_kesi(alpha, beta, A, B, o, ksi):
print('start calculating ksi......')
T = len(o)
temp = [0 for i in range(16)]
for t in range(T - 1):
k = 0
for i in range(4):
for j in range(4):
ksi[t][i][j] = alpha[t][i] + A[i][j] + B[j][ord(
o[t + 1])] + beta[t + 1][j]
temp[k] = ksi[t][i][j]
k += 1
s = Tool.log_sum(temp)
for i in range(4):
for j in range(4):
ksi[t][i][j] -= s
print('The calculation of kesi have been finished......')