python中分组

注：一个()代表一个分组

https://segmentfault.com/q/1010000000094918

http://www.tutorialspoint.com/python/python_reg_expressions.htm

http://www.cnblogs.com/huxi/archive/2010/07/04/1771073.html    python正则表达式指南

The match Function

This function attempts to match RE pattern to string with optional flags.

Here is the syntax for this function −

re.match(pattern, string, flags=0)

Here is the description of the parameters:

Parameter	Description
pattern	This is the regular expression to be matched.
string	This is the string, which would be searched to match the pattern at the beginning of string.
flags	You can specify different flags using bitwise OR (|). These are modifiers, which are listed in the table below.

The re.match function returns a match object on success, None on failure. We usegroup(num) or groups() function of match object to get matched expression.

Match Object Methods	Description
group(num=0)	This method returns entire match (or specific subgroup num)
groups()	This method returns all matching subgroups in a tuple (empty if there weren't any)

Example

#!/usr/bin/python
import re

line = "Cats are smarter than dogs"

matchObj = re.match( r'(.*) are (.*?) .*', line, re.M|re.I)

if matchObj:
   print "matchObj.group() : ", matchObj.group()
   print "matchObj.group(1) : ", matchObj.group(1)
   print "matchObj.group(2) : ", matchObj.group(2)
else:
   print "No match!!"

When the above code is executed, it produces following result −

matchObj.group() :  Cats are smarter than dogs
matchObj.group(1) :  Cats
matchObj.group(2) :  smarter

matchObj.groups()
('Cats', 'smarter')