在线正则表达式测试
http://tool.oschina.net/regex/
常见匹配模式
模式 |
描述 |
\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 [\t\n\r\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 |
\Z |
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 |
\n |
匹配一个换行符 |
\t |
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 )
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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( ‘^Hello\s\d\d\d\s\d{4}\s\w{10}.*Demo$‘ , content)
print (result)
print (result.group())
print (result.span())
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41
<_sre.SRE_Match object; span=(0, 41), match=‘Hello 123 4567 World_This is a Regex Demo‘>
Hello 123 4567 World_This is a Regex Demo
(0, 41)
泛匹配
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import re
content = ‘Hello 123 4567 World_This is a Regex Demo‘
result = re.match( ‘^Hello.*Demo$‘ , content)
print (result)
print (result.group())
print (result.span())
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<_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( ‘^Hello\s(\d+)\sWorld.*Demo$‘ , content)
print (result)
print (result.group( 1 ))
print (result.span())
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<_sre.SRE_Match object; span=(0, 40), match=‘Hello 1234567 World_This is a Regex Demo‘>
1234567
(0, 40)
贪婪匹配
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import re
content = ‘Hello 1234567 World_This is a Regex Demo‘
result = re.match( ‘^He.*(\d+).*Demo$‘ , content)
print (result)
print (result.group( 1 ))
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<_sre.SRE_Match object; span=(0, 40), match=‘Hello 1234567 World_This is a Regex Demo‘>
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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$‘ , content)
print (result)
print (result.group( 1 ))
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<_sre.SRE_Match object; span=(0, 40), match=‘Hello 1234567 World_This is a Regex Demo‘>
1234567
匹配模式
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import re
content = ‘‘‘Hello 1234567 World_This
is a Regex Demo
‘‘‘
result = re.match( ‘^He.*?(\d+).*?Demo$‘ , content, re.S)
print (result.group( 1 ))
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1234567
转义
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import re
content = ‘price is $5.00‘
result = re.match( ‘price is $5.00‘ , content)
print (result)
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None
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import re
content = ‘price is $5.00‘
result = re.match( ‘price is \$5\.00‘ , content)
print (result)
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<_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)
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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 ))
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<_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 ))
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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 ))
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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 ))
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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 ])
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output
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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 ])
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output
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)
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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)
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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)
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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())
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output
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)
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<_sre.SRE_Match object; span=(0, 40), match=‘Hello 1234567 World_This\nis a Regex Demo‘>
实战练习
源码在git上:https://gitee.com/longlovemeng/Spider.git
原文地址:https://www.cnblogs.com/yunlongaimeng/p/9802104.html
时间: 2024-07-31 23:41:30