python爬虫之BeautifulSoup 使用select方法详解

yipeiwu_com6年前Python爬虫

本文介绍了python爬虫之BeautifulSoup 使用select方法详解 ,分享给大家。具体如下:

<html><head><title>The Dormouse's story</title></head>
<body>
<p class="title" name="dromouse"><b>The Dormouse's story</b></p>
<p class="story">Once upon a time there were three little sisters; and their names were
<a href="http://example.com/elsie" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" class="sister" id="link1"><!-- Elsie --></a>,
<a href="http://example.com/lacie" rel="external nofollow" rel="external nofollow" rel="external nofollow" class="sister" id="link2">Lacie</a> and
<a href="http://example.com/tillie" rel="external nofollow" rel="external nofollow" rel="external nofollow" class="sister" id="link3">Tillie</a>;
and they lived at the bottom of a well.</p>
<p class="story">...</p>
"""

我们在写 CSS 时,标签名不加任何修饰,类名前加点,id名前加 #,在这里我们也可以利用类似的方法来筛选元素,用到的方法是 soup.select(),返回类型是 list

(1)通过标签名查找

print soup.select('title') 
#[<title>The Dormouse's story</title>]
 
print soup.select('a')
#[<a class="sister" href="http://example.com/elsie" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" id="link1"><!-- Elsie --></a>, <a class="sister" href="http://example.com/lacie" rel="external nofollow" rel="external nofollow" rel="external nofollow" id="link2">Lacie</a>, <a class="sister" href="http://example.com/tillie" rel="external nofollow" rel="external nofollow" rel="external nofollow" id="link3">Tillie</a>]
 
print soup.select('b')
#[<b>The Dormouse's story</b>]

(2)通过类名查找

print soup.select('.sister')
#[<a class="sister" href="http://example.com/elsie" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" id="link1"><!-- Elsie --></a>, <a class="sister" href="http://example.com/lacie" rel="external nofollow" rel="external nofollow" rel="external nofollow" id="link2">Lacie</a>, <a class="sister" href="http://example.com/tillie" rel="external nofollow" rel="external nofollow" rel="external nofollow" id="link3">Tillie</a>]

(3)通过 id 名查找

print soup.select('#link1')
#[<a class="sister" href="http://example.com/elsie" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" id="link1"><!-- Elsie --></a>]

(4)组合查找

组合查找即和写 class 文件时,标签名与类名、id名进行的组合原理是一样的,例如查找 p 标签中,id 等于 link1的内容,二者需要用空格分开

print soup.select('p #link1')
#[<a class="sister" href="http://example.com/elsie" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" id="link1"><!-- Elsie --></a>]

直接子标签查找

print soup.select("head > title")
#[<title>The Dormouse's story</title>]

(5)属性查找

查找时还可以加入属性元素,属性需要用中括号括起来,注意属性和标签属于同一节点,所以中间不能加空格,否则会无法匹配到。

print soup.select("head > title")
#[<title>The Dormouse's story</title>]
 
print soup.select('a[href="http://example.com/elsie" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" ]')
#[<a class="sister" href="http://example.com/elsie" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" id="link1"><!-- Elsie --></a>]

同样,属性仍然可以与上述查找方式组合,不在同一节点的空格隔开,同一节点的不加空格

print soup.select('p a[href="http://example.com/elsie" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" ]')
#[<a class="sister" href="http://example.com/elsie" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" id="link1"><!-- Elsie --></a>]

以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持【听图阁-专注于Python设计】。

相关文章

Python爬虫使用浏览器cookies:browsercookie过程解析

很多用Python的人可能都写过网络爬虫,自动化获取网络数据确实是一件令人愉悦的事情,而Python很好的帮助我们达到这种愉悦。然而,爬虫经常要碰到各种登录、验证的阻挠,让人灰心丧气(网...

python支持多线程的爬虫实例

python是支持多线程的, 主要是通过thread和threading这两个模块来实现的,本文主要给大家分享python实现多线程网页爬虫 一般来说,使用线程有两种模式, 一种是创建线...

python爬虫实现教程转换成 PDF 电子书

python爬虫实现教程转换成 PDF 电子书

写爬虫似乎没有比用 Python 更合适了,Python 社区提供的爬虫工具多得让你眼花缭乱,各种拿来就可以直接用的 library 分分钟就可以写出一个爬虫出来,今天就琢磨着写一个爬虫...

Python爬虫:将headers请求头字符串转为字典的方法

原生请求头字符串 raw_headers = """Host: open.tool.hexun.com Pragma: no-cache Cache-Control: no-cach...

python3爬取数据至mysql的方法

本文实例为大家分享了python3爬取数据至mysql的具体代码,供大家参考,具体内容如下 直接贴代码 #!/usr/local/bin/python3.5 # -*- codin...