re模块是python 中专门处理正则相关的模块
下面专门介绍一下正则表达式。
相关的正则测试网站推荐一个。 http://tool.oschina.net/regex/
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。
re.match(pattern,string,falg=0)
最常规的匹配
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$', content)
print(result)
print(result.group())
print(result.span())
结果:
41 <_sre.SRE_Match object; span=(0, 41), match='Hello 123 4567 World_This is a Regex Demo'> Hello 123 4567 World_This is a Regex Demo (0, 41)
泛匹配
import re
content = 'Hello 123 4567 World_This is a Regex Demo'
result = re.match('^Hello.*Demo$', content)
print(result)
print(result.group())
print(result.span())
结果:
<_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
import re
content = 'Hello 1234567 World_This is a Regex Demo'
result = re.match('^Hello\s(\d+)\sWorld.*Demo$', content)
print(result)
print(result.group(1))
print(result.span())
结果:
<_sre.SRE_Match object; span=(0, 40), match='Hello 1234567 World_This is a Regex Demo'> 1234567 (0, 40)
贪婪匹配
import re
content = 'Hello 1234567 World_This is a Regex Demo'
result = re.match('^He.*(\d+).*Demo$', content)
print(result)
print(result.group(1))
结果:
<_sre.SRE_Match object; span=(0, 40), match='Hello 1234567 World_This is a Regex Demo'> 7
非贪婪匹配
import re
content = 'Hello 1234567 World_This is a Regex Demo'
result = re.match('^He.*?(\d+).*Demo$', content)
print(result)
print(result.group(1))
结果:
<_sre.SRE_Match object; span=(0, 40), match='Hello 1234567 World_This is a Regex Demo'> 1234567
匹配模式
import re
content = '''Hello 1234567 World_This
is a Regex Demo
'''
result = re.match('^He.*?(\d+).*?Demo$', content, re.S)
print(result.group(1))
结果:
1234567
注意: re.s 可以让.*匹配换行符
转义
import re
content = 'price is $5.00'
result = re.match('price is \$5\.00', content)
print(result)
结果:
<_sre.SRE_Match object; span=(0, 14), match='price is $5.00'>
re.search
re.search 扫描整个字符串并返回第一个成功的匹配。
search 和match很像。但是search不用首字母和尾字母匹配。
匹配演练
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))
结果:
齐秦 往事随风