在线正则表达式测试
http://tool.oschina.net/regex/
常见匹配模式
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w | 匹配字母数字及下划线 |
W | 匹配非字母数字下划线 |
s | 匹配任意空白字符,等价于 [ f]. |
S | 匹配任意非空字符 |
d | 匹配任意数字,等价于 [0-9] |
D | 匹配任意非数字 |
A | 匹配字符串开始 |
匹配字符串结束,如果是存在换行,只匹配到换行前的结束字符串 | |
z | 匹配字符串结束 |
G | 匹配最后匹配完成的位置 |
匹配一个换行符 | |
匹配一个制表符 | |
^ | 匹配字符串的开头 |
$ | 匹配字符串的末尾。 |
. | 匹配任意字符,除了换行符,当re.DOTALL标记被指定时,则可以匹配包括换行符的任意字符。 |
[...] | 用来表示一组字符,单独列出:[amk] 匹配 'a','m'或'k' |
[^...] | 不在[]中的字符:[^abc] 匹配除了a,b,c之外的字符。 |
* | 匹配0个或多个的表达式。 |
+ | 匹配1个或多个的表达式。 |
? | 匹配0个或1个由前面的正则表达式定义的片段,非贪婪方式 |
{n} | 精确匹配n个前面表达式。 |
{n, m} | 匹配 n 到 m 次由前面的正则表达式定义的片段,贪婪方式 |
a|b | 匹配a或b |
( ) | 匹配括号内的表达式,也表示一个组 |
re.match
re.match 尝试从字符串的起始位置匹配一个模式,如果不是起始位置匹配成功的话,match()就返回none。
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re.match(pattern, string, flags = 0 ) |
最常规的匹配
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import re content = 'Hello 123 4567 World_This is a Regex Demo' print ( len (content)) result = re.match( '^Hellosdddsd{4}sw{10}.*Demo$' , content) print (result) print (result.group()) print (result.span()) |
41 <_sre.SRE_Match object; span=(0, 41), match='Hello 123 4567 World_This is a Regex Demo'> Hello 123 4567 World_This is a Regex Demo (0, 41)
泛匹配
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import re content = 'Hello 123 4567 World_This is a Regex Demo' result = re.match( '^Hello.*Demo$' , content) print (result) print (result.group()) print (result.span()) |
<_sre.SRE_Match object; span=(0, 41), match='Hello 123 4567 World_This is a Regex Demo'> Hello 123 4567 World_This is a Regex Demo (0, 41)
匹配目标
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import re content = 'Hello 1234567 World_This is a Regex Demo' result = re.match( '^Hellos(d+)sWorld.*Demo$' , content) print (result) print (result.group( 1 )) print (result.span()) |
<_sre.SRE_Match object; span=(0, 40), match='Hello 1234567 World_This is a Regex Demo'> 1234567 (0, 40)
贪婪匹配
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import re content = 'Hello 1234567 World_This is a Regex Demo' result = re.match( '^He.*(d+).*Demo$' , content) print (result) print (result.group( 1 )) |
<_sre.SRE_Match object; span=(0, 40), match='Hello 1234567 World_This is a Regex Demo'> 7
非贪婪匹配
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import re content = 'Hello 1234567 World_This is a Regex Demo' result = re.match( '^He.*?(d+).*Demo$' , content) print (result) print (result.group( 1 )) |
<_sre.SRE_Match object; span=(0, 40), match='Hello 1234567 World_This is a Regex Demo'> 1234567
匹配模式
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import re content = '''Hello 1234567 World_This is a Regex Demo ''' result = re.match( '^He.*?(d+).*?Demo$' , content, re.S) print (result.group( 1 )) |
1234567
转义
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import re content = 'price is $5.00' result = re.match( 'price is $5.00' , content) print (result) |
None
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import re content = 'price is $5.00' result = re.match( 'price is $5.00' , content) print (result) |
<_sre.SRE_Match object; span=(0, 14), match='price is $5.00'>
总结:尽量使用泛匹配、使用括号得到匹配目标、尽量使用非贪婪模式、有换行符就用re.S
re.search
re.search 扫描整个字符串并返回第一个成功的匹配。
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import re content = 'Extra stings Hello 1234567 World_This is a Regex Demo Extra stings' result = re.match( 'Hello.*?(d+).*?Demo' , content) print (result) |
None
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import re content = 'Extra stings Hello 1234567 World_This is a Regex Demo Extra stings' result = re.search( 'Hello.*?(d+).*?Demo' , content) print (result) print (result.group( 1 )) |
<_sre.SRE_Match object; span=(13, 53), match='Hello 1234567 World_This is a Regex Demo'> 1234567
总结:为匹配方便,能用search就不用match
匹配演练
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import re html = '''<div id="songs-list"> <h2 class="title">经典老歌</h2> <p class="introduction"> 经典老歌列表 </p> <ul id="list" class="list-group"> <li data-view="2">一路上有你</li> <li data-view="7"> <a href="/2.mp3" singer="任贤齐">沧海一声笑</a> </li> <li data-view="4" class="active"> <a href="/3.mp3" singer="齐秦">往事随风</a> </li> <li data-view="6"><a href="/4.mp3" singer="beyond">光辉岁月</a></li> <li data-view="5"><a href="/5.mp3" singer="陈慧琳">记事本</a></li> <li data-view="5"> <a href="/6.mp3" singer="邓丽君"><i class="fa fa-user"></i>但愿人长久</a> </li> </ul> </div>''' result = re.search( '<li.*?active.*?singer="(.*?)">(.*?)</a>' , html, re.S) if result: print (result.group( 1 ), result.group( 2 )) |
齐秦 往事随风
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import re html = '''<div id="songs-list"> <h2 class="title">经典老歌</h2> <p class="introduction"> 经典老歌列表 </p> <ul id="list" class="list-group"> <li data-view="2">一路上有你</li> <li data-view="7"> <a href="/2.mp3" singer="任贤齐">沧海一声笑</a> </li> <li data-view="4" class="active"> <a href="/3.mp3" singer="齐秦">往事随风</a> </li> <li data-view="6"><a href="/4.mp3" singer="beyond">光辉岁月</a></li> <li data-view="5"><a href="/5.mp3" singer="陈慧琳">记事本</a></li> <li data-view="5"> <a href="/6.mp3" singer="邓丽君">但愿人长久</a> </li> </ul> </div>''' result = re.search( '<li.*?singer="(.*?)">(.*?)</a>' , html, re.S) if result: print (result.group( 1 ), result.group( 2 )) |
任贤齐 沧海一声笑
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import re html = '''<div id="songs-list"> <h2 class="title">经典老歌</h2> <p class="introduction"> 经典老歌列表 </p> <ul id="list" class="list-group"> <li data-view="2">一路上有你</li> <li data-view="7"> <a href="/2.mp3" singer="任贤齐">沧海一声笑</a> </li> <li data-view="4" class="active"> <a href="/3.mp3" singer="齐秦">往事随风</a> </li> <li data-view="6"><a href="/4.mp3" singer="beyond">光辉岁月</a></li> <li data-view="5"><a href="/5.mp3" singer="陈慧琳">记事本</a></li> <li data-view="5"> <a href="/6.mp3" singer="邓丽君">但愿人长久</a> </li> </ul> </div>''' result = re.search( '<li.*?singer="(.*?)">(.*?)</a>' , html) if result: print (result.group( 1 ), result.group( 2 )) |
beyond 光辉岁月
re.findall
搜索字符串,以列表形式返回全部能匹配的子串。
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import re html = '''<div id="songs-list"> <h2 class="title">经典老歌</h2> <p class="introduction"> 经典老歌列表 </p> <ul id="list" class="list-group"> <li data-view="2">一路上有你</li> <li data-view="7"> <a href="/2.mp3" singer="任贤齐">沧海一声笑</a> </li> <li data-view="4" class="active"> <a href="/3.mp3" singer="齐秦">往事随风</a> </li> <li data-view="6"><a href="/4.mp3" singer="beyond">光辉岁月</a></li> <li data-view="5"><a href="/5.mp3" singer="陈慧琳">记事本</a></li> <li data-view="5"> <a href="/6.mp3" singer="邓丽君">但愿人长久</a> </li> </ul> </div>''' results = re.findall( '<li.*?href="(.*?)".*?singer="(.*?)">(.*?)</a>' , html, re.S) print (results) print ( type (results)) for result in results: print (result) print (result[ 0 ], result[ 1 ], result[ 2 ]) |
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
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import re html = '''<div id="songs-list"> <h2 class="title">经典老歌</h2> <p class="introduction"> 经典老歌列表 </p> <ul id="list" class="list-group"> <li data-view="2">一路上有你</li> <li data-view="7"> <a href="/2.mp3" singer="任贤齐">沧海一声笑</a> </li> <li data-view="4" class="active"> <a href="/3.mp3" singer="齐秦">往事随风</a> </li> <li data-view="6"><a href="/4.mp3" singer="beyond">光辉岁月</a></li> <li data-view="5"><a href="/5.mp3" singer="陈慧琳">记事本</a></li> <li data-view="5"> <a href="/6.mp3" singer="邓丽君">但愿人长久</a> </li> </ul> </div>''' results = re.findall( '<li.*?>s*?(<a.*?>)?(w+)(</a>)?s*?</li>' , html, re.S) print (results) for result in results: print (result[ 1 ]) |
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
re.sub
替换字符串中每一个匹配的子串后返回替换后的字符串。
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import re content = 'Extra stings Hello 1234567 World_This is a Regex Demo Extra stings' content = re.sub( 'd+' , '', content) print (content) |
Extra stings Hello World_This is a Regex Demo Extra stings
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import re content = 'Extra stings Hello 1234567 World_This is a Regex Demo Extra stings' content = re.sub( 'd+' , 'Replacement' , content) print (content) |
Extra stings Hello Replacement World_This is a Regex Demo Extra stings
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import re content = 'Extra stings Hello 1234567 World_This is a Regex Demo Extra stings' content = re.sub( '(d+)' , r '1 8910' , content) print (content) |
Extra stings Hello 1234567 8910 World_This is a Regex Demo Extra stings
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import re html = '''<div id="songs-list"> <h2 class="title">经典老歌</h2> <p class="introduction"> 经典老歌列表 </p> <ul id="list" class="list-group"> <li data-view="2">一路上有你</li> <li data-view="7"> <a href="/2.mp3" singer="任贤齐">沧海一声笑</a> </li> <li data-view="4" class="active"> <a href="/3.mp3" singer="齐秦">往事随风</a> </li> <li data-view="6"><a href="/4.mp3" singer="beyond">光辉岁月</a></li> <li data-view="5"><a href="/5.mp3" singer="陈慧琳">记事本</a></li> <li data-view="5"> <a href="/6.mp3" singer="邓丽君">但愿人长久</a> </li> </ul> </div>''' html = re.sub( '<a.*?>|</a>' , '', html) print (html) results = re.findall( '<li.*?>(.*?)</li>' , html, re.S) print (results) for result in results: print (result.strip()) |
![](https://images.cnblogs.com/OutliningIndicators/ContractedBlock.gif)
re.compile
将正则字符串编译成正则表达式对象
将一个正则表达式串编译成正则对象,以便于复用该匹配模式:
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import re content = '''Hello 1234567 World_This is a Regex Demo''' pattern = re. compile ( 'Hello.*Demo' , re.S) result = re.match(pattern, content) #result = re.match('Hello.*Demo', content, re.S) print (result) |
<_sre.SRE_Match object; span=(0, 40), match='Hello 1234567 World_This is a Regex Demo'>
实战练习
源码在git上:https://gitee.com/longlovemeng/Spider.git