Python 模块RE整理

本文主要是介绍Python 模块RE整理，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！

python 模块RE正则表达式模块整理

notice:

python 中的字符串分为两种，一种由8位的ASCALL码字符组成字符串，另一种为Unicode字符串，在匹配的过程中二者不能混用，只能同种类型的情况进行匹配。
正则表达式使用反斜杠” \ “来代表特殊形式或用作转义字符，这里跟Python的语法冲突，因此，Python用” \\ “表示正则表达式中的” \ “，因为正则表达式中如果要匹配” \ “，需要用\来转义，变成” \ “，而Python语法中又需要对字符串中每一个\进行转义，所以就变成了” \\ “。为了使正则表达式具有更好的可读性，Python特别设计了原始字符串(raw string)，raw string就是用’r’作为字符串的前缀，如 r”\n”：表示两个字符”\”和”n”，而不是换行符。Python中写正则表达式时推荐使用这种形式。

Python中re模块中的特殊字符

. 匹配任意字符
[] 用来匹配一个指定的字符类别，所谓的字符类别就是你想匹配的一个字符集，对于字符集中的字符可以理解成或的关系
^ 对于字符串，表示字符串的开头
对于^加上一个其他数字或字符，表示取反。比如，[^5]表示除了5之外的任意字符。[^^]表示除了^字符之外任意字符。
$ 匹配字符串的末尾，或者匹配换行之前的字符串末尾
* 对于前一个字符重复0到无穷次
+ 对于前一个字符重复1到无穷次
? 对于前一个字符重复0到1次
{m,n} 对于前一个字符重复次数在为m到n次。
{0,} == *
{1,} ==
{0,1} == ?
{m} 对于前一个字符重复m次

python中re模块中特殊转义序列（字符）

\A 匹配字符串的开头
\b 匹配一个空字符（仅对一个单词word的开始或结束有效）
\B 与\b含义相反
\d 匹配任何十进制数；它相当于类 [0-9]
\D 匹配任何非数字字符；它相当于类 [^0-9]
\s 匹配任何空白字符；它相当于类 [ \t\n\r\f\v]
\S 匹配任何非空白字符；它相当于类 [^ \t\n\r\f\v]
\w 匹配任何字母数字字符；它相当于类 [a-zA-Z0-9_]
\W 匹配任何非字母数字字符；它相当于类 [^a-zA-Z0-9_]
\Z 匹配字符串的结尾

相关函数

re.match(pattern, string, flags=0)

re.match 尝试从字符串的开始匹配一个模式，也就是从字符串开头开始匹配,Try to apply the pattern at the start of the string, returning a match object, or None if no match was found

re.search(pattern, string, flags=0)

　re.search函数会在字符串内查找模式匹配,只到找到第一个匹配然后返回，如果字符串没有匹配，则返回None。Scan through string looking for a match to the pattern, returning a match object, or None if no match was found.

re.findall(pattern, string, flags=0)

re.findall可以获取字符串中所有匹配的字符串。Return a list of all non-overlapping matches in the string. If one or more capturing groups are present in the pattern, return a list of groups; this will be a list of tuples if the pattern has more than one group,Empty matches are included in the result.

#!/usr/bin/python2.7
# -*- ecoding:utf-8 -*-
# 支持 python3.x， python2.x 去掉print后的括号 
# 演示（）以及 match, search, findall 异同
import retext = "They have coffee 123 handsome , should be almost ... as well"
m = re.match(r"(\w+)", text)
if m:print (m.group(0))
else:print ('not match')m = re.match(r"(\w+)(\W+)(\w+)", text)
if m:print (m.group(0))
else:print ('not match')m = re.search(r"(\d\w+)", text)
if m:print (m.group(0))
else:print ('not match')
m = re.search(r"\d(\w+)(\W+)(\w+)", text)
if m:print (m.group(0))
else:print ('not match')m = re.findall(r'(\d+\s)', text)
print (m)
m = re.findall(r"(\w+)", text)
print (m)
m = re.findall(r"(\w+)(\W+)(\w+)", text)
print (m)
'''
#output:
They
They have
123
123 handsome
['123 ']
['They', 'have', 'coffee', '123', 'handsome', 'should', 'be', 'almost', 'as', 'well']
[('They', ' ', 'have'), ('coffee', ' ', '123'), ('handsome', ' , ', 'should'), ('be', ' ', 'almost'), ('as', ' ', 'well')]
'''

简单的html页面中 url匹配

#!/usr/bin/python2.7
# -*- ecoding:utf-8 -*-
# 支持 python3.x， python2.x 去掉print后的括号 import recontext = '''
<div class="list_item article_item"><div class="article_title"><span class="ico ico_type_Original"></span><h1><span class="link_title"><a href="/u011461385/article/details/52448295">tettt</a></span></h1></div><div class="article_description"> tttttttttt...        </div><div class="article_manage"><span class="link_postdate">2016-09-06 11:21</span><span class="link_view" title="阅读次数"><a href="/u011461385/article/details/52448295" title="阅读次数">阅读</a>(5)</span><span class="link_comments" title="评论次数"><a href="/u011461385/article/details/52448295#comments" title="评论次数" onclick="_gaq.push(['_trackEvent','function', 'onclick', 'blog_articles_pinglun'])">评论</a>(0)</span></div><div class="clear"></div></div>
'''pattern1 = r'<div class="(\S+)"'
listed = re.findall(pattern1, context)
print (listed)pattern2= r'<a href="([\S]*?)"'
listed = re.findall(pattern2, context)
print (listed)
pattern2= r'<a href="(.*?)"'
listed = re.findall(pattern2, context)
print (listed)
pattern2= r'<a href="(\S+)"'
listed = re.findall(pattern2, context)'''
#output:
['article_title', 'article_description', 'article_manage', 'clear']
['/u011461385/article/details/52448295', '/u011461385/article/details/52448295', '/u011461385/article/details/52448295#comments']
['/u011461385/article/details/52448295', '/u011461385/article/details/52448295', '/u011461385/article/details/52448295#comments']
['/u011461385/article/details/52448295', '/u011461385/article/details/52448295', '/u011461385/article/details/52448295#comments']'''