贝叶斯-实现新闻数据分类

用贝叶斯实现新闻分类

• 重点，停用词的去除，词向量的构建， TF-IDF原理
• 停用词可以通过停用词表进行去除
• 词向量构建，本文是通过简单的词频模型，来构建词向量
• IF-IDF 通过词频和关键词提取，来判断一个单词出现的重要性

import pandas as pd
import jieba


pd.set_option('display.max_columns', None)   #显示完整的列
df_news = pd.read_table('./data/val.txt', names=['category', 'theme', 'URL','content'], encoding='utf-8')
df_news = df_news.dropna()
# print(df_news.head())


print(df_news.shape)

# 分词，使用结巴分词
content = df_news.content.values.tolist()
# print(content[1000])

content_S = []
for line in content:
    current_segment = jieba.lcut(line)
    if len(current_segment) > 1 and current_segment != '
':
        content_S.append(current_segment)


# print(content_S[1000])

df_content = pd.DataFrame({'content_S': content_S})
# print(df_content.head())

stopwords = pd.read_csv('stopwords.txt', index_col=False, sep='	', quoting=3, names=['stopwords'], encoding='utf-8')
# print(stopwords.head())

def drop_stopwords(contents, stopwords):
    contents_clean = []
    all_words = []
    for line in contents:
        line_clean = []
        for word in line:
            if word in stopwords:
                continue
            line_clean.append(word)
            all_words.append(str(word))
        contents_clean.append(line_clean)
    return contents_clean, all_words

contents = df_content.content_S.values.tolist()
stopwords = stopwords.stopwords.values.tolist()
contents_clean, all_wrods  = drop_stopwords(contents, stopwords)

df_content = pd.DataFrame({'contents_clean': contents_clean})
# print(df_content.head())

df_all_words = pd.DataFrame({'all_words': all_wrods})
# print(df_all_words.head())
import numpy
words_count = df_all_words.groupby(by=['all_words'])['all_words'].agg({'count': numpy.size})
words_count = words_count.reset_index().sort_values(by=['count'], ascending=False)
# print(words_count.head())


# from wordcloud import WordCloud
# import matplotlib.pyplot as plt
# import matplotlib
# matplotlib.rcParams['figure.figsize'] = (10.0, 5.0)
#
# wordcloud = WordCloud(font_path='./simhei.ttf', background_color='white', max_font_size=80)
# word_frequence = {x[0]: x[1] for x in words_count.head(100).values}
# wordcloud = wordcloud.fit_words(word_frequence)
# plt.imshow(wordcloud)
# plt.show()


# TF-IDF 提取关键词
# import jieba.analyse
# index = 2000
# print(df_news['content'][index])
# content_S_str = "".join(content_S[index])
# print(content_S_str)
# print(" ".join(jieba.analyse.extract_tags(content_S_str, topK=5, withWeight=False)))

# LDA:主题模型
# 格式要求：list of list 形式，分词好的整个语料
from gensim import corpora, models, similarities
import gensim

# 做映射，相当于词袋
dictionary = corpora.Dictionary(contents_clean)
corpus = [dictionary.doc2bow(sentence) for sentence in contents_clean]

lda = gensim.models.ldamodel.LdaModel(corpus=corpus, id2word=dictionary, num_topics=20) # 类始于K-means 自己指定K值

# 一号分类结果
print(lda.print_topic(1, topn=5))

# for topic in lda.print_topics(num_topics=20, num_words=5):
#     print(topic[1])


df_train = pd.DataFrame({"contents_clean": contents_clean, 'label': df_news['category']})
print(df_train.tail())

print(df_train.label.unique())


label_mapping = {'汽车':1, '财经':2, '科技':3, '健康':4, '体育':5, '教育':6, '文化':7, '军事':8, '娱乐':9, '时尚':10}
df_train['label'] = df_train['label'].map(label_mapping)

print(df_train.head())

from sklearn.model_selection import train_test_split

x_train, x_test, y_train, y_test = train_test_split(df_train['contents_clean'].values, df_train['label'].values, random_state=0)

print(x_test[0][1])

# 统计
words = []

for line_index in range(len(x_train)):
    try:
        words.append(' '.join(x_train[line_index]))
    except:
        print(line_index)
print(words[0])
print(len(words))

from sklearn.feature_extraction.text import CountVectorizer

vec = CountVectorizer(analyzer='word', max_features=4000, lowercase=False)
vec.fit(words)

from sklearn.naive_bayes import MultinomialNB
classifier = MultinomialNB()
classifier.fit(vec.transform(words), y_train)

test_words = []

for line_index in range(len(x_test)):
    try:
       test_words.append(' '.join(x_test[line_index]))
    except:
        print(line_index)

print(type(test_words[0]))

print('---------------------')

print(classifier.score(vec.transform(test_words), y_test))

文本向量的测试

from sklearn.feature_extraction.text import CountVectorizer

texts = ['dog cat fish', 'dog cat cat', 'fish bird', 'bird']
cv = CountVectorizer()
cv_fit = cv.fit_transform(texts)
print(cv.get_feature_names())
print(cv_fit.toarray())

print(cv_fit.toarray().sum(axis=0))