Python网络爬虫之中国大学排名爬虫代码实例分析学习笔记手札及代码实战

“中国大学排名定向爬虫”实例介绍

网址：http://www.zuihaodaxue.cn/zuihaodaxuepaiming2016.html

定向爬虫可行性

<tbody class="hidden_zhpm" style="text-align:center;">
                <tr class="alt"><td>1</td>
				<td><div align="left">清华大学</div></td>
				<td>北京市</td><td>95.9</td><td class="hidden-xs need-hidden indicator5">100.0</td><td class="hidden-xs need-hidden indicator6"  style="display:none;">97.90%</td><td class="hidden-xs need-hidden indicator7"  style="display:none;">37342</td><td class="hidden-xs need-hidden indicator8"  style="display:none;">1.298</td><td class="hidden-xs need-hidden indicator9"  style="display:none;">1177</td><td class="hidden-xs need-hidden indicator10"  style="display:none;">109</td><td class="hidden-xs need-hidden indicator11"  style="display:none;">1137711</td><td class="hidden-xs need-hidden indicator12"  style="display:none;">1187</td><td class="hidden-xs need-hidden indicator13"  style="display:none;">593522</td></tr><tr><td>2</td>
				<td><div align="left">北京大学</div></td>
				<td>北京市</td><td>82.6</td><td class="hidden-xs need-hidden indicator5">98.9</td><td class="hidden-xs need-hidden indicator6"  style="display:none;">95.96%</td><td class="hidden-xs need-hidden indicator7"  style="display:none;">36137</td><td class="hidden-xs need-hidden indicator8"  style="display:none;">1.294</td><td class="hidden-xs need-hidden indicator9"  style="display:none;">986</td><td class="hidden-xs need-hidden indicator10"  style="display:none;">87</td><td class="hidden-xs need-hidden indicator11"  style="display:none;">439403</td><td class="hidden-xs need-hidden indicator12"  style="display:none;">799</td><td class="hidden-xs need-hidden indicator13"  style="display:none;">7343</td></tr><tr class="alt"><td>3</td>
				<td><div align="left">浙江大学</div></td>
				<td>浙江省</td><td>80</td><td class="hidden-xs need-hidden indicator5">88.8</td><td class="hidden-xs need-hidden indicator6"  style="display:none;">96.46%</td><td class="hidden-xs need-hidden indicator7"  style="display:none;">41188</td><td class="hidden-xs need-hidden indicator8"  style="display:none;">1.059</td><td class="hidden-xs need-hidden indicator9"  style="display:none;">803</td><td class="hidden-xs need-hidden indicator10"  style="display:none;">86</td><td class="hidden-xs need-hidden indicator11"  style="display:none;">959511</td><td class="hidden-xs need-hidden indicator12"  style="display:none;">833</td><td class="hidden-xs need-hidden indicator13"  style="display:none;">64392</td></tr><tr><td>4</td>

定向爬虫可行性:通过robots协议查看
http://www.zuihaodaxue.cn/robots.txt

程序的结构设计

步骤1：从网络上获取大学排名网页内容
getHTMLText()
步骤2：提取网页内容中信息到合适的数据结构
fillUnivList()
步骤3：利用数据结构展示并输出结果
printUnivList()

"中国大学排名定向爬虫"实例编写

import requests

from bs4 import BeautifulSoup

def getHTMLText(url):
    try:
        r = requests.get(url,timeout=30)
        r.raise_for_status()
        r.encoding = r.apparent_encoding
        return r.text
    except:
        return""
    
import bs4
def fillUnivList(ulist,html):
    soup = BeautifulSoup(html,"html.parser")
    for tr in soup.find('tbody').children:
        if isinstance(tr,bs4.element.Tag):
            tds = tr('td')
            ulist.append([tds[0].string,tds[1].string,tds[3].string])

def printUnivList(ulist,num):
    tplt = "{0:^10}\t{1:{3}^10}\t{2:^10}"
    print("{:^10}\t{:^6}\t{:^10}".format("排名","学校名称","总分",chr(12288)))
    for i in range(num):
        u=ulist[i]
        print(tplt.format(u[0],u[1],u[2],chr(12288)))

def main():
    uinfo = []
    url = 'http://www.zuihaodaxue.cn/zuihaodaxuepaiming2016.html'
    html = getHTMLText(url)
    fillUnivList(uinfo,html)
    printUnivList(uinfo,20) #20 univs
main()