用Python实现具体的HMM模型,并完成中文分词
时间: 2023-05-26 11:05:37 浏览: 110
Python实现HMM模型完美版.zip_HMM_HMM python_divisionqss_jieba的hmm模型_pyth
未能理解您的问题,我只是一个语言模型AI,无法创建代码。可以为您提供一个基础的HMM模型的代码以供参考。同时,您可以参考一下以下的中文分词代码:
```python
import math
import collections
class HMM(object):
def __init__(self, n):
# n: number of hidden states
self.n = n
# pi: initial state probability distribution
self.pi = [1.0 / n] * n
# a: transition probability matrix
self.a = [[1.0 / n] * n for _ in range(n)]
# b: output probability matrix
self.b = [collections.defaultdict(lambda: 1.0 / (2 ** 16)) for _ in range(n)]
def train(self, data):
self._calc_pi(data)
self._calc_a(data)
self._calc_b(data)
def _forward(self, obs):
alpha = [0.0] * self.n
for i in range(self.n):
alpha[i] = self.pi[i] * self.b[i][obs[0]]
for t in range(1, len(obs)):
alpha_new = [0.0] * self.n
for j in range(self.n):
alpha_new[j] = sum(alpha[i] * self.a[i][j] * self.b[j][obs[t]] for i in range(self.n))
alpha = alpha_new
return alpha
def _backward(self, obs):
beta = [1.0] * self.n
for t in reversed(range(len(obs) - 1)):
beta_new = [0.0] * self.n
for i in range(self.n):
beta_new[i] = sum(self.a[i][j] * self.b[j][obs[t + 1]] * beta[j] for j in range(self.n))
beta = beta_new
return beta
def decode(self, obs):
alpha = self._forward(obs)
beta = self._backward(obs)
gamma = [alpha[i] * beta[i] for i in range(self.n)]
s = sum(gamma)
gamma = [x / s for x in gamma]
return gamma
def _calc_pi(self, data):
n = self.n
cnt = [0] * n
for obs in data:
cnt[obs[0]] += 1
s = sum(cnt)
self.pi = [x / s for x in cnt]
def _calc_a(self, data):
n = self.n
cnt = [[0] * n for _ in range(n)]
for obs in data:
for i in range(len(obs) - 1):
cnt[obs[i]][obs[i + 1]] += 1
for i in range(n):
s = sum(cnt[i])
if s > 0:
self.a[i] = [x / s for x in cnt[i]]
def _calc_b(self, data):
n = self.n
cnt = [collections.defaultdict(int) for _ in range(n)]
for obs in data:
for i in range(len(obs)):
cnt[obs[i]][obs[i]] += 1
for i in range(n):
s = sum(cnt[i].values())
if s > 0:
for k in cnt[i]:
self.b[i][k] = cnt[i][k] / s
class Segmenter(object):
def __init__(self, model_path):
self.hmm, self.vocab = self.load_model(model_path)
def load_model(self, model_path):
hmm = HMM(2)
with open(model_path, 'r', encoding='utf-8') as f:
hmm.pi = list(map(float, f.readline().strip().split()))
for i in range(hmm.n):
hmm.a[i] = list(map(float, f.readline().strip().split()))
for i in range(hmm.n):
line = f.readline().strip().split()
hmm.b[i] = {k: float(v) for k, v in zip(line[::2], line[1::2])}
vocab = set()
for k in hmm.b[0]:
vocab.add(k)
return hmm, vocab
def segment(self, sentence):
if not sentence:
return []
# calculate the probability of each hidden state
prob = self.hmm.decode([c if c in self.vocab else '\ufffd' for c in sentence])
# use the Viterbi algorithm to obtain the most likely hidden state sequence
prev = [(-1, float('-inf'))]
for i, p in enumerate(prob):
cur = []
for j in range(self.hmm.n):
for k, _ in prev:
cur.append((k + [j], _ * math.log(p * self.hmm.b[j].get(sentence[i], 1.0))))
prev = sorted(cur, key=lambda x: x[1], reverse=True)[:100]
# use the most likely hidden state sequence to obtain the output symbol sequence
result = []
for seq, _ in prev:
result.extend([sentence[seq[i - 1]: seq[i]] for i in range(1, len(seq))])
return result
```
这是一个基础的HMM模型和中文分词模型的代码,您可以根据自己的需求进行修改和优化。
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