PyQuery库也是一个非常强大又灵活的网页解析库，如果你有前端开发经验的，都应该接触过jQuery,那么PyQuery就是你非常绝佳的选择，PyQuery 是 Python 仿照 jQuery 的严格实现。语法与 jQuery 几乎完全相同，所以不用再去费心去记一些奇怪的方法了。

官网地址：http://pyquery.readthedocs.io/en/latest/
jQuery参考文档： http://jquery.cuishifeng.cn/

初始化

初始化的时候一般有三种传入方式：传入字符串，传入url,传入文件

字符串初始化

html = '''
<div>
    <ul>
         <li class="item-0">first item</li>
         <li class="item-1"><a href="link2.html">second item</a></li>
         <li class="item-0 active"><a href="link3.html"><span class="bold">third item</span></a></li>
         <li class="item-1 active"><a href="link4.html">fourth item</a></li>
         <li class="item-0"><a href="link5.html">fifth item</a></li>
     </ul>
</div>
'''
from pyquery import PyQuery as pq
doc = pq(html) #主要是理解这步即可
print(type(doc))
print(doc('li'))

输出如下：

<class 'pyquery.pyquery.PyQuery'>
<li class="item-0">first item</li>
         <li class="item-1"><a href="link2.html">second item</a></li>
         <li class="item-0 active"><a href="link3.html"><span class="bold">third item</span></a></li>
         <li class="item-1 active"><a href="link4.html">fourth item</a></li>
         <li class="item-0"><a href="link5.html">fifth item</a></li>

由于PyQuery写起来比较麻烦，所以我们导入的时候都会添加别名：
from pyquery import PyQuery as pq
这里我们可以知道上述代码中的doc其实就是一个pyquery对象，我们可以通过doc可以进行元素的选择，其实这里就是一个css选择器，所以CSS选择器的规则都可以用，直接doc(标签名)就可以获取所有的该标签的内容，如果想要获取class 则doc('.class_name'),如果是id则doc('#id_name')....
URL初始化

from pyquery import PyQuery as pq
"https://www.baidu.com"
doc = pq(url="https://www.baidu.com" ,encoding="utf-8")
print(type(doc))
print(doc('div'))

在传URL的时候可以选择输出的编码，比如我上面这个例子，如果不加encoding容易出现乱码。
输出如下：

文件初始化
我们先将html以记事本的形式存入文档

from pyquery import PyQuery as pq

doc = pq(filename=r'C:\Users\董贺贺\Desktop\测试.txt')
print(type(doc))
print(doc('li')) 

输出结果如下：

<class 'pyquery.pyquery.PyQuery'>
<li class="item-0">first item</li>
         <li class="item-1"><a href="link2.html">second item</a></li>
         <li class="item-0 active"><a href="link3.html"><span class="bold">third item</span></a></li>
         <li class="item-1 active"><a href="link4.html">fourth item</a></li>
         <li class="item-0"><a href="link5.html">fifth item</a></li>
     

基本的CSS选择器

html = '''
<div id="container">
    <ul class="list">
         <li class="item-0">first item</li>
         <li class="item-1"><a href="link2.html">second item</a></li>
         <li class="item-0 active"><a href="link3.html"><span class="bold">third item</span></a></li>
         <li class="item-1 active"><a href="link4.html">fourth item</a></li>
         <li class="item-0"><a href="link5.html">fifth item</a></li>
     </ul>
 </div>
'''
from pyquery import PyQuery as pq
doc = pq(html)
print(type(doc))
print(doc('#container .list li'))

输出结果如下：

<class 'pyquery.pyquery.PyQuery'>
<li class="item-0">first item</li>
         <li class="item-1"><a href="link2.html">second item</a></li>
         <li class="item-0 active"><a href="link3.html"><span class="bold">third item</span></a></li>
         <li class="item-1 active"><a href="link4.html">fourth item</a></li>
         <li class="item-0"><a href="link5.html">fifth item</a></li>    

这里我们需要注意的一个地方是doc('#container .list li')，这里的三者之间的并不是必须要挨着，只要是层级关系就可以,下面是常用的CSS选择器方法：

查找元素

子元素
children,find
代码例子：

html = '''
<div id="container">
    <ul class="list">
         <li class="item-0">first item</li>
         <li class="item-1"><a href="link2.html">second item</a></li>
         <li class="item-0 active"><a href="link3.html"><span class="bold">third item</span></a></li>
         <li class="item-1 active"><a href="link4.html">fourth item</a></li>
         <li class="item-0"><a href="link5.html">fifth item</a></li>
     </ul>
 </div>
'''
from pyquery import PyQuery as pq
doc = pq(html)
print(type(doc))
item = doc('.list')
print(type(item))
print(type(item.find('li')))
print(item.find('li'))

输出如下：

<class 'pyquery.pyquery.PyQuery'>
<class 'pyquery.pyquery.PyQuery'>
<class 'pyquery.pyquery.PyQuery'>
<li class="item-0">first item</li>
         <li class="item-1"><a href="link2.html">second item</a></li>
         <li class="item-0 active"><a href="link3.html"><span class="bold">third item</span></a></li>
         <li class="item-1 active"><a href="link4.html">fourth item</a></li>
         <li class="item-0"><a href="link5.html">fifth item</a></li>

从结果里我们也可以看出通过pyquery找到结果其实还是一个pyquery对象，可以继续查找，上述中的代码中的items.find('li') 则表示查找ul里的所有的li标签
当然这里通过children可以实现同样的效果,并且通过.children方法得到的结果也是一个pyquery对象

html = '''
<div id="container">
    <ul class="list">
         <li class="item-0">first item</li>
         <li class="item-1"><a href="link2.html">second item</a></li>
         <li class="item-0 active"><a href="link3.html"><span class="bold">third item</span></a></li>
         <li class="item-1 active"><a href="link4.html">fourth item</a></li>
         <li class="item-0"><a href="link5.html">fifth item</a></li>
     </ul>
 </div>
'''
from pyquery import PyQuery as pq
doc = pq(html)
print(type(doc))
item = doc('.list')
li = item.children()
print(li)

输出结果：

<class 'pyquery.pyquery.PyQuery'>
<li class="item-0">first item</li>
         <li class="item-1"><a href="link2.html">second item</a></li>
         <li class="item-0 active"><a href="link3.html"><span class="bold">third item</span></a></li>
         <li class="item-1 active"><a href="link4.html">fourth item</a></li>
         <li class="item-0"><a href="link5.html">fifth item</a></li>

同时在children中还可以用CSS方法

html = '''
<div id="container">
    <ul class="list">
         <li class="item-0">first item</li>
         <li class="item-1"><a href="link2.html">second item</a></li>
         <li class="item-0 active"><a href="link3.html"><span class="bold">third item</span></a></li>
         <li class="item-1 active"><a href="link4.html">fourth item</a></li>
         <li class="item-0"><a href="link5.html">fifth item</a></li>
     </ul>
 </div>
'''
from pyquery import PyQuery as pq
doc = pq(html)
print(type(doc))
items = doc('.list')
li = items.children('.active')
print(li)

输出如下：

<class 'pyquery.pyquery.PyQuery'>
<li class="item-0 active"><a href="link3.html"><span class="bold">third item</span></a></li>
         <li class="item-1 active"><a href="link4.html">fourth item</a></li>

父元素
parent,parents方法
通过.parent就可以找到父元素的内容，例子如下：

html = '''
<div id="container">
    <ul class="list">
         <li class="item-0">first item</li>
         <li class="item-1"><a href="link2.html">second item</a></li>
         <li class="item-0 active"><a href="link3.html"><span class="bold">third item</span></a></li>
         <li class="item-1 active"><a href="link4.html">fourth item</a></li>
         <li class="item-0"><a href="link5.html">fifth item</a></li>
     </ul>
 </div>
'''
from pyquery import PyQuery as pq
doc = pq(html)
items = doc('.list')
container = items.parent()
print(container)

输出如下：

<div id="container">
    <ul class="list">
         <li class="item-0">first item</li>
         <li class="item-1"><a href="link2.html">second item</a></li>
         <li class="item-0 active"><a href="link3.html"><span class="bold">third item</span></a></li>
         <li class="item-1 active"><a href="link4.html">fourth item</a></li>
         <li class="item-0"><a href="link5.html">fifth item</a></li>
     </ul>
 </div>

.parent()方法是查找的父元素，通过.parents()就可以找到祖先节点的内容，例子如下：

html = '''
<div class="wrap">
    <div id="container">
        <ul class="list">
             <li class="item-0">first item</li>
             <li class="item-1"><a href="link2.html">second item</a></li>
             <li class="item-0 active"><a href="link3.html"><span class="bold">third item</span></a></li>
             <li class="item-1 active"><a href="link4.html">fourth item</a></li>
             <li class="item-0"><a href="link5.html">fifth item</a></li>
         </ul>
     </div>
 </div>
'''
from pyquery import PyQuery as pq
doc = pq(html)
items = doc('.list')
container = items.parents()
print(container)

输出如下：

<div class="wrap">
    <div id="container">
        <ul class="list">
             <li class="item-0">first item</li>
             <li class="item-1"><a href="link2.html">second item</a></li>
             <li class="item-0 active"><a href="link3.html"><span class="bold">third item</span></a></li>
             <li class="item-1 active"><a href="link4.html">fourth item</a></li>
             <li class="item-0"><a href="link5.html">fifth item</a></li>
         </ul>
     </div>
 </div><div id="container">
        <ul class="list">
             <li class="item-0">first item</li>
             <li class="item-1"><a href="link2.html">second item</a></li>
             <li class="item-0 active"><a href="link3.html"><span class="bold">third item</span></a></li>
             <li class="item-1 active"><a href="link4.html">fourth item</a></li>
             <li class="item-0"><a href="link5.html">fifth item</a></li>
         </ul>
     </div>
 

同样我们通过.parents查找的时候也可以添加css选择器来进行内容的筛选

html = '''
<div class="wrap">
    <div id="container">
        <ul class="list">
             <li class="item-0">first item</li>
             <li class="item-1"><a href="link2.html">second item</a></li>
             <li class="item-0 active"><a href="link3.html"><span class="bold">third item</span></a></li>
             <li class="item-1 active"><a href="link4.html">fourth item</a></li>
             <li class="item-0"><a href="link5.html">fifth item</a></li>
         </ul>
     </div>
 </div>
'''
from pyquery import PyQuery as pq
doc = pq(html)
items = doc('.list')
container = items.parents('.wrap')
print(container)

输出如下：

<div class="wrap">
    <div id="container">
        <ul class="list">
             <li class="item-0">first item</li>
             <li class="item-1"><a href="link2.html">second item</a></li>
             <li class="item-0 active"><a href="link3.html"><span class="bold">third item</span></a></li>
             <li class="item-1 active"><a href="link4.html">fourth item</a></li>
             <li class="item-0"><a href="link5.html">fifth item</a></li>
         </ul>
     </div>
 </div>

兄弟元素
siblings

html = '''
<div class="wrap">
    <div id="container">
        <ul class="list">
             <li class="item-0">first item</li>
             <li class="item-1"><a href="link2.html">second item</a></li>
             <li class="item-0 active"><a href="link3.html"><span class="bold">third item</span></a></li>
             <li class="item-1 active"><a href="link4.html">fourth item</a></li>
             <li class="item-0"><a href="link5.html">fifth item</a></li>
         </ul>
     </div>
 </div>
'''
from pyquery import PyQuery as pq
doc = pq(html)
li = doc('.list .item-0.active')
lis = li.siblings()
print(lis)

输出如下：

<li class="item-1"><a href="link2.html">second item</a></li>
             <li class="item-0">first item</li>
             <li class="item-1 active"><a href="link4.html">fourth item</a></li>
             <li class="item-0"><a href="link5.html">fifth item</a></li>

代码中doc('.list .item-0.active') 中的.tem-0和.active是紧挨着的，所以表示是并的关系，这样满足条件的就剩下一个了：thired item的那个标签了
这样在通过.siblings就可以获取所有的兄弟标签，当然这里是不包括自己的
同样的在.siblings()里也是可以通过CSS选择器进行筛选

html = '''
<div class="wrap">
    <div id="container">
        <ul class="list">
             <li class="item-0">first item</li>
             <li class="item-1"><a href="link2.html">second item</a></li>
             <li class="item-0 active"><a href="link3.html"><span class="bold">third item</span></a></li>
             <li class="item-1 active"><a href="link4.html">fourth item</a></li>
             <li class="item-0"><a href="link5.html">fifth item</a></li>
         </ul>
     </div>
 </div>
'''
from pyquery import PyQuery as pq
doc = pq(html)
li = doc('.list .item-0.active')
lis = li.siblings('.item-0')
print(lis)

输出如下:

<li class="item-0">first item</li>
             <li class="item-0"><a href="link5.html">fifth item</a></li>

遍历
单个元素

html = '''
<div class="wrap">
    <div id="container">
        <ul class="list">
             <li class="item-0">first item</li>
             <li class="item-1"><a href="link2.html">second item</a></li>
             <li class="item-0 active"><a href="link3.html"><span class="bold">third item</span></a></li>
             <li class="item-1 active"><a href="link4.html">fourth item</a></li>
             <li class="item-0"><a href="link5.html">fifth item</a></li>
         </ul>
     </div>
 </div>
'''
from pyquery import PyQuery as pq
doc = pq(html)
li = doc('.item-0.active')
print(li)

lis = doc('li').items()
for li in lis:
    print(type(li))
    print(li)

运行结果如下：从结果中我们可以看出通过items()可以得到一个生成器，并且我们通过for循环得到的每个元素依然是一个pyquery对象。
输出如下:

<li class="item-0 active"><a href="link3.html"><span class="bold">third item</span></a></li>
             
<class 'pyquery.pyquery.PyQuery'>
<li class="item-0">first item</li>
             
<class 'pyquery.pyquery.PyQuery'>
<li class="item-1"><a href="link2.html">second item</a></li>
             
<class 'pyquery.pyquery.PyQuery'>
<li class="item-0 active"><a href="link3.html"><span class="bold">third item</span></a></li>
             
<class 'pyquery.pyquery.PyQuery'>
<li class="item-1 active"><a href="link4.html">fourth item</a></li>
             
<class 'pyquery.pyquery.PyQuery'>
<li class="item-0"><a href="link5.html">fifth item</a></li>

获取信息

获取属性
pyquery对象.attr(属性名)
pyquery对象.attr.属性名

html = '''
<div class="wrap">
    <div id="container">
        <ul class="list">
             <li class="item-0">first item</li>
             <li class="item-1"><a href="link2.html">second item</a></li>
             <li class="item-0 active"><a href="link3.html"><span class="bold">third item</span></a></li>
             <li class="item-1 active"><a href="link4.html">fourth item</a></li>
             <li class="item-0"><a href="link5.html">fifth item</a></li>
         </ul>
     </div>
 </div>
'''
from pyquery import PyQuery as pq
doc = pq(html)
a = doc(".item-0.active a")
print(a)

print(a.attr('href'))
print(a.attr.href)

输出如下：

<a href="link3.html"><span class="bold">third item</span></a>
link3.html
link3.html

个人比较喜欢第一种写法
所以这里我们也可以知道获得属性值的时候可以直接a.attr(属性名)或者a.attr.属性名
获取文本
在很多时候我们是需要获取被html标签包含的文本信息,通过.text()就可以获取文本信息

html = '''
<div class="wrap">
    <div id="container">
        <ul class="list">
             <li class="item-0">first item</li>
             <li class="item-1"><a href="link2.html">second item</a></li>
             <li class="item-0 active"><a href="link3.html"><span class="bold">third item</span></a></li>
             <li class="item-1 active"><a href="link4.html">fourth item</a></li>
             <li class="item-0"><a href="link5.html">fifth item</a></li>
         </ul>
     </div>
 </div>
'''
from pyquery import PyQuery as pq
doc = pq(html)
a = doc(".item-0.active a")
print(a)

print(a.text())

输出如下：

<a href="link3.html"><span class="bold">third item</span></a>
third item

获取html
我们通过.html()的方式可以获取当前标签所包含的html信息，例子如下：

html = '''
<div class="wrap">
    <div id="container">
        <ul class="list">
             <li class="item-0">first item</li>
             <li class="item-1"><a href="link2.html">second item</a></li>
             <li class="item-0 active"><a href="link3.html"><span class="bold">third item</span></a></li>
             <li class="item-1 active"><a href="link4.html">fourth item</a></li>
             <li class="item-0"><a href="link5.html">fifth item</a></li>
         </ul>
     </div>
 </div>
'''
from pyquery import PyQuery as pq
doc = pq(html)
lis = doc('#container .list li').items()
print(lis)
for li in lis:
    print(li.html())

输出如下：

first item
<a href="link2.html">second item</a>
<a href="link3.html"><span class="bold">third item</span></a>
<a href="link4.html">fourth item</a>
<a href="link5.html">fifth item</a>

DOM操作

addClass、removeClass
熟悉前端操作的话，通过这两个操作可以添加和删除属性

html = '''
<div class="wrap">
    <div id="container">
        <ul class="list">
             <li class="item-0">first item</li>
             <li class="item-1"><a href="link2.html">second item</a></li>
             <li class="item-0 active"><a href="link3.html"><span class="bold">third item</span></a></li>
             <li class="item-1 active"><a href="link4.html">fourth item</a></li>
             <li class="item-0"><a href="link5.html">fifth item</a></li>
         </ul>
     </div>
 </div>
'''
from pyquery import PyQuery as pq
doc = pq(html)
li = doc('#container .list .item-1.active')
print(li)
li.remove_class('active')
print(li)
li.add_class('active')
print(li)

输出如下：

<li class="item-1 active"><a href="link4.html">fourth item</a></li>
             
<li class="item-1"><a href="link4.html">fourth item</a></li>
             
<li class="item-1 active"><a href="link4.html">fourth item</a></li>

attr,css
同样的我们可以通过attr给标签添加和修改属性，
如果之前没有该属性则是添加，如果有则是修改
我们也可以通过css添加一些css属性，这个时候，标签的属性里会多一个style属性

html = '''
<div class="wrap">
    <div id="container">
        <ul class="list">
             <li class="item-0">first item</li>
             <li class="item-1"><a href="link2.html">second item</a></li>
             <li class="item-0 active"><a href="link3.html"><span class="bold">third item</span></a></li>
             <li class="item-1 active"><a href="link4.html">fourth item</a></li>
             <li class="item-0"><a href="link5.html">fifth item</a></li>
         </ul>
     </div>
 </div>
'''
from pyquery import PyQuery as pq
doc = pq(html)
li = doc('.item-0.active')
print(li)
li.attr('name', 'link')
print(li)
li.css('font-size', '14px')
print(li)

结果如下:

<li class="item-0 active"><a href="link3.html"><span class="bold">third item</span></a></li>
             
<li class="item-0 active" name="link"><a href="link3.html"><span class="bold">third item</span></a></li>
             
<li class="item-0 active" name="link" style="font-size: 14px"><a href="link3.html"><span class="bold">third item</span></a></li>

remove
有时候我们获取文本信息的时候可能并列的会有一些其他标签干扰，这个时候通过remove就可以将无用的或者干扰的标签直接删除，从而方便操作

html = '''
<div class="wrap">
    Hello, World
    <p>This is a paragraph.</p>
 </div>
'''
from pyquery import PyQuery as pq
doc = pq(html)
wrap = doc('.wrap')
print(wrap.text())
wrap.find('p').remove()
print(wrap.text())

输出如下：

Hello, World
This is a paragraph.
Hello, World

pyquery中DOM的其他api操作参考：http://pyquery.readthedocs.io/en/latest/api.html