9.python3实用编程技巧进阶（四）

概述4.1.如何读写csv数据  爬取豆瓣top250书籍 import requestsimport jsonimport csvfrom bs4 import BeautifulSoupbooks = [] def book_name(url): res = requests.get(url) html = res.text soup = Be 4.1.如何读写csv数据

 爬取豆瓣top250书籍

import requestsimport Jsonimport csvfrom bs4 import BeautifulSoupbooks = []
def book_name(url):    res = requests.get(url)    HTML = res.text    soup = BeautifulSoup(HTML,‘HTML.parser‘)    items = soup.find(class_="grID-16-8 clearfix").find(class_="indent").find_all(‘@R_419_5991@‘)    for i in items:        book = []        Title = i.find(class_="pl2").find(‘a‘)        book.append(‘《‘ + Title.text.replace(‘ ‘,‘‘).replace(‘\n‘,‘‘) + ‘》‘)        star = i.find(class_="star clearfix").find(class_="rating_nums")        book.append(star.text + ‘分‘)        try:            brIEf = i.find(class_="quote").find(class_="inq")        except AttributeError:            book.append(‘”暂无简介“‘)        else:            book.append(brIEf.text)        link = i.find(class_="pl2").find(‘a‘)[‘href‘]        book.append(link)        global books        books.append(book)        print(book)    try:        next = soup.find(class_="paginator").find(class_="next").find(‘a‘)[‘href‘]    # 翻到最后一页    except TypeError:        return 0    else:        return nextnext = ‘https://book.douban.com/top250?start=0&filter=‘count = 0while next != 0:    count += 1    next = book_name(next)    print(‘-----------以上是第‘ + str(count) + ‘页的内容-----------‘)csv_file = open(‘D:/top250_books.csv‘,‘w‘,newline=‘‘,enCoding=‘utf-8‘)w = csv.writer(csv_file)w.writerow([‘书名‘,‘评分‘,‘简介‘,‘链接‘])for b in books:    w.writerow(b)

结果

把评分为9.0的书籍保存到book_out.csv文件中

‘‘‘1.爬取豆瓣评分排行前250本书,保存为top250.csv2.读取top250.csv文件，把评分为9.0以上的书籍保存到另外一个csv文件中‘‘‘import csv#打开的时候必须用enCoding=‘utf-8‘，否则报错with open(‘top250_books.csv‘,enCoding=‘utf-8‘) as rf:    reader = csv.reader(rf)    #读取头部    headers = next(reader)    with open(‘books_out.csv‘,enCoding=‘utf-8‘) as wf:        writer = csv.writer(wf)        #把头部信息写进去        writer.writerow(headers)        for book in reader:            #获取评分            score = book[1]            #把评分大于9.0的过滤出来            if score and float(score) >= 9.0:                writer.writerow(book)

 4.2.如何读写excel

 安装两个库

pip install xlrd xlwt

读取excel

#4.2.如何读取excelimport xlrdbook = xlrd.open_workbook(‘demo.xlsx‘)sheet = book.sheet_by_index(0)#获取有多少行多少列print(sheet.nrows)   #4print(sheet.ncols)   #4print(sheet.cell(0,0))          #text:‘姓名‘print(sheet.cell_value(0,0))    #姓名print(sheet.row_values(0))      #[‘姓名‘,‘语文‘,‘数学‘,‘外语‘]print(sheet.row_values(1,1))    #[95.0,99.0,96.0]

求分数的总和

#4.2.如何读写excelimport xlrd,xlwtrbook = xlrd.open_workbook(‘demo.xlsx‘)rsheet = rbook.sheet_by_index(0)k = rsheet.ncols#在最后添加一列 ‘总分’rsheet.put_cell(0,k,xlrd.XL_CELL_TEXT,‘总分‘,None)for i in range(1,rsheet.nrows):    #求分数总和    t = sum(rsheet.row_values(i,1))    rsheet.put_cell(i,xlrd.XL_CELL_NUMBER,t,None)wbook = xlwt.Workbook()wsheet = wbook.add_sheet(rsheet.name)for i in range(rsheet.nrows):    for j in range(rsheet.ncols):        wsheet.write(i,j,rsheet.cell_value(i,j))wbook.save(‘out.xlsx‘)

 结果

总结

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