Python re 正则

python  re　group用法

>>> p=re.compile('(a)b')
>>> m=p.match('ab')
>>> m.group()
'ab'
>>> m.group(0)
'ab'
>>> m.group(1)
'a'
>>> m.group(2)
Traceback (most recent call last):
  File "", line 1, in <module>
IndexError: no such group
>>> p=re.compile('(a(b)c)d')
>>> m=p.match('abcd')
>>> m.group()
'abcd'
>>> m.group(0)
'abcd'
>>> m.group(1)
'abc'
>>> m.group(2)
'b'
>>> m.group(3)
Traceback (most recent call last):
  File "", line 1, in <module>
IndexError: no such group
>>>

Python 2.7.6 (default, Mar 22 2014, 22:59:56)
[GCC 4.8.2] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import re
>>> re.split('\W+','Words, words, words')
['Words', 'words', 'words']
>>> re.split('(\W+)','Words, words, words')
['Words', ', ', 'words', ', ', 'words']
>>> re.split('\W+','Words, words, words',1)
['Words', 'words, words']
>>> re.split('[a-f]+','0a3B9',flags=re.IGNORECASE)
['0', '3', '9']