import re 
pattern = "this" 
text = "Does this text match the pattern?" 
match = re.search(pattern, text) # 返回一个Match对象 
print match.re.pattern # 要匹配的正则表达式"this"
print match.string   # 匹配的文本"Does this match the pattern?" 
print match.start()   # 匹配的开始位置 5
print match.end()    # 匹配的结束位置 9

import re 
regex = re.compile("this") 
text = "Does this text match the pattern?" 
match = regex.search(text) 
if match: 
  print "match" 
  match.group(0)  #返回匹配的字符串  
else:
  print "not match" 

import re 
pattern = 'ab' 
text = 'abbaaabbbbaaaaaa' 
re.findall(pattern, text)  # 返回['ab', 'ab'] 

import re 
pattern = 'ab' 
text = 'abbaaabbbbaaaaaa' 
match = re.finditer(pattern, text)  
for m in match:
  print m.start() 
  print m.end()

import re 
re.search("^travell?er$", "traveler")  # True 
re.search("^travell?er$", "traveller")  # True  
re.search("^ab\*", "abbbbbbb")      # True,返回"abbbbbbb" 
re.search("^ab\*?", "abbbbbbb")     # True,返回"a" 
re.search("^ab+", "abbbbbbb")      # True,返回"abbbbbbb" 
re.search("^ab+?", "abbbbbbb")      # True,返回"ab" 

import re
the_str = "This is some text -- with punctuation" 
re.search(r'^\w+', the_str).group(0)    # This
re.search(r'\A\w+', the_str).group(0)   # This 
re.search(r'\w+\S*$', the_str).group(0)  # punctuation 
re.search(r'\w+\S*\Z', the_str).group(0)  # punctuation 
re.search(r'\w*t\W*', the_str).group(0)  # text -- 
re.search(r'\bt\w+', the_str).group(0)   # text 
re.search(r'\Bt*\B', the_str).group(0)   # 没有匹配 

import re 
the_str = "--aabb123bbaa" 
pattern = r'(\W+)([a-z]+)(\d+)(\D+)' 
match = re.search(pattern, the_str)  
match.groups()  # ('--', 'aabb', '123', 'bbaa') 
match.group(0)  # '--aabb123bbaa' 
match.group(1)  # '--' 
match.group(2)  # 'aabb' 
match.group(3)  # '123' 
match.group(4)  # 'bbaa'

import re 
the_str = "--aabb123bbaa" 
pattern = r'(?P<not_al_and_num>\W+)(?P<al>[a-z]+)(?P<num>\d+)(?P<not_num>\D+)' 
match = re.search(pattern, the_str)  
match.groups()  # ('--', 'aabb', '123', 'bbaa') 
match.groupdict() # {'not_al_and_num': '--', 'not_num': 'bbaa', 'num': '123', 'al': 'aabb'} 
match.group(0)          # '--aabb123bbaa' 
match.group(1)          # '--' 
match.group(2)          # 'aabb' 
match.group(3)          # '123' 
match.group(4)          # 'bbaa'  
match.group('not_al_and_num')  # '--'
match.group('al')         # 'aabb' 
match.group('num')        # '123' '
match.group('not_num')      # 'bbaa'

import re 
the_str = "this Text" 
re.findall(r'\bt\w+', the_str)  # ['this'] 
re.findall(r'\bt\w+', the_str, re.IGNORECASE) # ['this', 'Text']