探索tf-idf提取文本關鍵詞

TF-IDF（term frequency–inverse document frequency）是一種用於信息檢索與數據挖掘的常用加權技術。TF意思是詞頻(Term Frequency)，IDF意思是逆文本頻率指數(Inverse Document Frequency)。

TF-IDF實際上是：TF * IDF，TF詞頻(Term Frequency)，IDF逆向文件頻率(Inverse Document Frequency)。

TF表示詞條在文檔d中出現的頻率。

IDF的主要思想是：如果包含詞條t的文檔越少，也就是n越小，IDF越大，則說明詞條t具有很好的類別區分能力。

 

注意事項：

userdict.txt  ：是我需要增加專業性的詞彙的詞庫

stop_words.txt：是我的停用詞詞庫

df_data       ：數據庫中100篇文章的text文檔（這裏df_data是一個文檔集，每篇文章佔據一行，100篇文章則是100行顯示。）讀取的時候默認是每一行識別爲一篇文章

完整代碼可以直接複製使用：

#! /usr/bin/python
# -*- coding: utf8 -*-
# @Time    : 2019/3/4 15:40
# @Author  : yukang
# 來源：https://blog.csdn.net/a2099948768/article/details/89189587

import sys,codecs
import pandas as pd
import numpy as np
import jieba.posseg
import jieba.analyse
from pyquery import PyQuery
from sklearn.feature_extraction.text import TfidfTransformer
from sklearn.feature_extraction.text import CountVectorizer
from MysqlDBPool import *
from Kmeans_word import *
"""
TF-IDF權重
    1，CountVectorizer 構建詞頻舉證
    2，TfidfTransformer 構建tfidf權重計算
    3，文本的關鍵詞
    4，對應的tfidf矩陣
"""

jieba.load_userdict('./userdict.txt')  # 加載外部 用戶詞典

# 數據預處理操作： 分詞，去停用詞，詞性篩選
def dataPrepos(text,stopkey):
    l = []
    pos = ['n','nz','v','vd','vn','l','a','d']  # https://blog.csdn.net/a2099948768/article/details/82216906 有註釋
    seg = jieba.posseg.cut(PyQuery(text).text())
    for i in seg:
        if i.word not in stopkey and i.flag in pos:
            l.append(i.word)
    return l

# tf-idf獲取文本top10關鍵詞
def getKeywords_tfidf(data,stopkey,topK):
    idList,titleList,abstractList = data['id'],data['title'],data['abstract']
    corpus = []  #  將所有文檔輸出到一個list中，一行就是一個文檔
    for index in range(len(idList)):
        text = '%s。%s'%(titleList[index],abstractList[index])
        text = dataPrepos(text,stopkey) # 文本預處理
        text = " ".join(text)
        corpus.append(text)
    # 1，構建詞頻矩陣，將文本中的詞語轉換成詞頻矩陣
    vectorizer = CountVectorizer()
    X = vectorizer.fit_transform(corpus) # 詞頻矩陣，a[i][j]:表示j詞在第i個文本中的詞頻
    # 2，統計每個詞的tf-idf權重
    transformer = TfidfTransformer()
    tfidf = transformer.fit_transform(X)
    # 3，獲取詞袋模型中的關鍵詞
    word = vectorizer.get_feature_names()
    # 4，獲取tf-idf矩陣，a[i][j]表示j詞在i篇文本中的tf-idf權重
    weight = tfidf.toarray()
    # 5，打印詞語權重
    ids, titles, keys = [],[],[]
    for i in range(len(weight)):
        # print("----------這裏輸出第",i+1,"篇文本的詞語tf-idf--------")
        ids.append(idList[i])
        titles.append(titleList[i])
        df_word,df_weight = [],[] # 當前文章的所有詞彙列表，詞彙對應的權重列表
        for j in range(len(word)):
            # print(word[j],weight[i][j])
            df_word.append(word[j])
            df_weight.append(weight[i][j])
        df_word = pd.DataFrame(df_word,columns=['word'])
        df_weight = pd.DataFrame(df_weight,columns=['weight'])
        word_weight = pd.concat([df_word,df_weight],axis=1) # 拼接詞彙列表和權重列表
        getkeywords_kmeans(word_weight, 100)  # 對關鍵詞做聚類
        word_weight = word_weight.sort_values(by='weight', ascending=False) # 按照權重值降序排列
        keyword = np.array(word_weight['word']) # 選擇詞彙列並轉成數組格式
        word_split = [keyword[x] for x in range(0,topK)]
        word_split = " ".join(word_split)
        keys.append(word_split.encode("utf-8"))
    result = pd.DataFrame({"id":ids,"title":titles,"key":keys},columns=["id","title","key"])
    return result

def main():
    topK = 150
    select_data = "SELECT ID,TITLE,FACT,RESULT,BASIS FROM `wenshu_detail` WHERE ID>0 AND ID<101"
    all_data = mysql_pool_client.exec_query(select_data)
    df_data = pd.DataFrame([[i[0],i[1],i[2]+i[3]+i[4]] for i in all_data], columns=['id','title','abstract'])
    # # 讀取數據集
    # dataFile = "./text.csv"
    # data = pd.read_csv(dataFile)
    # 停用詞
    stopkey = [w.strip() for w in codecs.open("./stop_words.txt","r",encoding="utf-8").readlines()]
    # tf-idf關鍵詞抽取
    result = getKeywords_tfidf(df_data,stopkey,topK)
    print(result)

if __name__ == '__main__':
    main()