根据tf/idf构建的词向量空间和输出的高频特征词以及分好类、具有类标号的文件夹下的中文文本,使用朴素贝叶斯算法训练分类模型,并返回分类模型的准确性、精准度、召回率
时间: 2024-05-13 15:16:48 浏览: 13
好的,下面是具体步骤:
1. 构建词向量空间:
使用中文分词工具(如jieba)对文本进行分词,并过滤停用词等无意义的词语,得到文本中的关键词。然后使用tf/idf算法计算每个关键词在整个文本集合中的重要性,得到每个文本的词向量。
2. 特征选择:
根据tf/idf算法计算每个文本中词语的重要性,选择出高频特征词,作为朴素贝叶斯算法的特征。
3. 训练模型:
将具有类标号的文件夹下的中文文本分为训练集和测试集,使用朴素贝叶斯算法进行训练。训练过程中,将训练集中的每个文本的词向量和对应的类别传入算法中进行训练。
4. 评估模型:
用测试集中的每个文本的词向量作为输入,预测其所属类别,然后将预测结果与真实结果进行比较,计算模型的准确性、精准度和召回率。
代码实现如下:
```
import jieba
import os
import math
import random
# 读取文件夹中的文本,返回文本内容
def read_file(path):
with open(path, 'r', encoding='utf-8') as f:
content = f.read()
return content
# 分词并返回词语列表
def cut_words(content):
words = jieba.cut(content)
return [word for word in words if word.strip()]
# 计算tf值
def calc_tf(word, words):
return words.count(word) / len(words)
# 计算idf值
def calc_idf(word, texts):
return math.log(len(texts) / (sum(1 for text in texts if word in text)))
# 计算tf-idf值
def calc_tf_idf(word, words, texts):
return calc_tf(word, words) * calc_idf(word, texts)
# 构建词向量空间
def build_word_vector_space(texts):
words_list = set()
for text in texts:
words_list.update(text)
words_list = list(words_list)
words_list.sort()
vectors = []
for text in texts:
vector = [calc_tf_idf(word, text, texts) for word in words_list]
vectors.append(vector)
return vectors
# 特征选择,选择高频特征词作为朴素贝叶斯算法的特征
def feature_selection(vectors, labels, k):
feature_words = []
feature_values = []
for i in range(len(vectors[0])):
values = [vector[i] for vector in vectors]
if sum(values) > k:
feature_words.append(i)
feature_values.append(values)
feature_values = list(zip(*feature_values))
labels = list(zip(labels, vectors))
return feature_words, feature_values, labels
# 计算条件概率
def calc_conditional_prob(word_index, feature_values, labels):
probs = {}
for label, vector in labels:
if label not in probs:
probs[label] = []
value = feature_values[word_index][labels.index((label, vector))]
probs[label].append(value)
return probs
# 计算先验概率
def calc_prior_prob(labels):
n = len(labels)
prior_probs = {}
for label in labels:
if label not in prior_probs:
prior_probs[label] = 0
prior_probs[label] += 1
for label in prior_probs:
prior_probs[label] /= n
return prior_probs
# 训练模型
def train(feature_words, feature_values, labels):
conditional_probs = {}
for word_index in feature_words:
probs = calc_conditional_prob(word_index, feature_values, labels)
for label in probs:
probs[label] = sum(probs[label]) / len(probs[label])
conditional_probs[word_index] = probs
prior_probs = calc_prior_prob([label for label, vector in labels])
return prior_probs, conditional_probs
# 预测
def predict(vector, prior_probs, conditional_probs):
probs = dict(prior_probs)
for i in range(len(vector)):
if i not in conditional_probs:
continue
for label in probs:
probs[label] *= conditional_probs[i][label] ** vector[i]
return max(probs, key=probs.get)
# 计算准确性、精准度和召回率
def evaluate(test_vectors, test_labels, prior_probs, conditional_probs):
correct_count = 0
positive_count = 0
true_positive_count = 0
for vector, label in zip(test_vectors, test_labels):
predict_label = predict(vector, prior_probs, conditional_probs)
if predict_label == label:
correct_count += 1
if predict_label == '1':
positive_count += 1
if label == '1' and predict_label == '1':
true_positive_count += 1
accuracy = correct_count / len(test_vectors)
precision = true_positive_count / positive_count if positive_count > 0 else 0
recall = true_positive_count / sum(1 for label in test_labels if label == '1')
return accuracy, precision, recall
# 加载数据集
def load_dataset(path):
texts = []
labels = []
for label in os.listdir(path):
label_path = os.path.join(path, label)
for filename in os.listdir(label_path):
file_path = os.path.join(label_path, filename)
content = read_file(file_path)
words = cut_words(content)
texts.append(words)
labels.append(label)
return texts, labels
# 随机划分训练集和测试集
def split_dataset(texts, labels, ratio=0.8):
dataset = list(zip(texts, labels))
random.shuffle(dataset)
n = int(len(dataset) * ratio)
train_dataset = dataset[:n]
test_dataset = dataset[n:]
train_texts, train_labels = zip(*train_dataset)
test_texts, test_labels = zip(*test_dataset)
return train_texts, train_labels, test_texts, test_labels
if __name__ == '__main__':
# 加载数据集
texts, labels = load_dataset('corpus')
# 随机划分训练集和测试集
train_texts, train_labels, test_texts, test_labels = split_dataset(texts, labels)
# 构建词向量空间
vectors = build_word_vector_space(train_texts + test_texts)
# 特征选择
feature_words, feature_values, labels = feature_selection(vectors, train_labels + test_labels, 10)
# 训练模型
prior_probs, conditional_probs = train(feature_words, feature_values, labels)
# 评估模型
accuracy, precision, recall = evaluate(vectors[len(train_texts):], test_labels, prior_probs, conditional_probs)
print('Accuracy:', accuracy)
print('Precision:', precision)
print('Recall:', recall)
```
需要注意的是,上面的代码只是一个简单的示例,对于实际应用中的数据集和问题,需要根据具体情况进行调整和优化。