在python环境下进行,编写出实验代码,编写一个基于HMM的词性标注程序。任务:利用结巴对CDIAL-BIAS-race文件进行分词与词性标注,将语料分成测试集与训练集(一般为1:4的比例)。在训练集上统计HMM中初始概率、发射概率、转移概率估算所需的参数,利用Viterbi算法,实现基于HMM的词性标注程序。 编写评价程序,计算HMM在测试集上的词性标注准确率。
时间: 2024-03-20 19:42:48 浏览: 85
HMM模型+维特比算法实现分词词性标注.py
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好的,请先确保已经安装好结巴分词库。
以下是基于HMM的词性标注程序的实现:
```python
import jieba.posseg as pseg
import random
# 加载语料库
corpus_file = 'CDIAL-BIAS-race.txt'
corpus = []
with open(corpus_file, 'r', encoding='utf-8') as f:
for line in f.readlines():
corpus.append(line.strip())
# 划分训练集和测试集
random.shuffle(corpus)
train_size = int(len(corpus) * 0.8)
train_corpus = corpus[:train_size]
test_corpus = corpus[train_size:]
# 统计HMM所需的参数
states = set()
observations = set()
start_prob = {}
emit_prob = {}
trans_prob = {}
for sentence in train_corpus:
words = pseg.cut(sentence)
prev_state = None
for w, s in words:
states.add(s)
observations.add(w)
if prev_state is None:
start_prob[s] = start_prob.get(s, 0) + 1
else:
trans_prob[(prev_state, s)] = trans_prob.get((prev_state, s), 0) + 1
emit_prob[(s, w)] = emit_prob.get((s, w), 0) + 1
prev_state = s
# 计算概率
for s in states:
start_prob[s] = start_prob.get(s, 0) / len(train_corpus)
for o in observations:
emit_prob[(s, o)] = emit_prob.get((s, o), 0) / sum([emit_prob.get((s, w), 0) for w in observations])
for s2 in states:
trans_prob[(s, s2)] = trans_prob.get((s, s2), 0) / sum([trans_prob.get((s, s3), 0) for s3 in states])
# Viterbi算法
def viterbi(obs, states, start_p, trans_p, emit_p):
V = [{}]
path = {}
for y in states:
V[0][y] = start_p.get(y, 0) * emit_p.get((y, obs[0]), 0)
path[y] = [y]
for t in range(1, len(obs)):
V.append({})
newpath = {}
for y in states:
(prob, state) = max([(V[t-1][y0] * trans_p.get((y0, y), 0) * emit_p.get((y, obs[t]), 0), y0) for y0 in states])
V[t][y] = prob
newpath[y] = path[state] + [y]
path = newpath
(prob, state) = max([(V[len(obs)-1][y], y) for y in states])
return (prob, path[state])
# 评价程序
def evaluate(test_corpus, states, start_prob, trans_prob, emit_prob):
total = 0
correct = 0
for sentence in test_corpus:
words = pseg.cut(sentence)
obs = [w for w, s in words]
tags = [s for w, s in words]
_, pred_tags = viterbi(obs, states, start_prob, trans_prob, emit_prob)
total += len(tags)
correct += sum([1 for i in range(len(tags)) if tags[i] == pred_tags[i]])
return correct / total
# 计算词性标注准确率
accuracy = evaluate(test_corpus, states, start_prob, trans_prob, emit_prob)
print('词性标注准确率:', accuracy)
```
这个程序首先加载CDIAL-BIAS-race语料库,然后按照1:4的比例划分训练集和测试集。接着统计HMM所需的参数:初始概率、发射概率和转移概率,并计算它们的概率。最后,使用Viterbi算法对测试集进行词性标注,并使用评价程序计算HMM在测试集上的词性标注准确率。
注意,这个程序需要一些时间才能完成运行,因为要处理的语料库比较大。在运行期间,请耐心等待。
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