【Python爬虫】Re(正则表达式)库入门

水深无声 2023-02-25 02:10 45阅读 0赞

## 正则表达式的概念 ##

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# 正则表达式的语法 #

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# Re库的基本使用 #

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练习：

>>> import re
    >>> match=re.search(r'[1-9]\d{5}','BIT 100081')
    >>> if match:
        print(match.group(0))
    
        
    100081
    >>>

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练习：

>>> import re
    >>> match=re.match(r'[1-9]\d{5}','BIT 100081')
    >>> if match:
        match.group(0)
    
        
    >>> match.group(0)
    Traceback (most recent call last):
      File "<pyshell#5>", line 1, in <module>
        match.group(0)
    AttributeError: 'NoneType' object has no attribute 'group'
    >>> match=re.match(r'[1-9]\d{5}','100081 BIT')
    >>> if match:
        match.group(0)
    
        
    '100081'
    >>>

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练习：

>>> import re
    >>> ls=re.findall(r'[1-9]\d{5}','BIT 100081 TSU100084')
    >>> ls
    ['100081', '100084']
    >>>

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练习：

>>> import re
    >>> re.split(r'[1-9]\d{5}','BIT100081 TSU100084')
    ['BIT', ' TSU', '']
    >>> re.split(r'[1-9]\d{5}','BIT100081 TSU100084',maxsplit=1)
    ['BIT', ' TSU100084']
    >>>

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练习：

>>> import re
    >>> for m in re.finditer(r'[1-9]\d{5}','BIT100081 TSU100084'):
        if m:
            print(m.group(0))
    
            
    100081
    100084

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练习：

>>> import re
    >>> re.sub(r'[1-9]\d{5}',':zipcode','BIT100081 TSU100084')
    'BIT:zipcode TSU:zipcode'
    >>>

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# Re库的match对象 #

>>> import re
    >>> match=re.search(r'[1-9]\d{5}','BIT 100081')
    >>> if match:
        print(match.group(0))
    
        
    100081
    >>> type(match)
    <class 're.Match'>
    >>>

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练习：

>>> import re
    >>> m=re.search(r'[1-9]\d{5}','BIT 100081 TSU100084')
    >>> m.string
    'BIT 100081 TSU100084'
    >>> m.re
    re.compile('[1-9]\\d{5}')
    >>> m.pos
    0
    >>> m.endpos
    20
    >>> m.group(0)
    '100081'
    >>> m.start()
    4
    >>> m.end()
    10
    >>> m.span()
    (4, 10)
    >>>

# Re库的贪婪匹配和最小匹配 #

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