PYTHON 正则表达示入门

确实是实践出真知，自己手打代码之后，以前停在理论上的东东，慢慢可以进入实战了。

比如，MATCH和SEARCH之间的区别。

#encoding: UTF-8
import re

pattern = re.compile(r'hello')
match = pattern.match('hello world!')
if match:
    print match.group()

pattern2 = re.compile(r'world')
match2 = pattern2.search('hello world.')
if match2:
    print match2.group()

pattern3 = re.compile(r'\d+')
re_string = 'one1two2three3four4'
print pattern3.split(re_string)
print pattern3.findall(re_string)
for i in pattern3.finditer(re_string):
    print i.group(),
print

m = re.match(r'(\w+) (\w+)(?P<sign>.*)','hello world!!')
print "m.string:",m.string
print "m.re:",m.re
print "m.pos:",m.pos
print "m.endpos:",m.endpos
print "m.lastindex:",m.lastindex
print "m.lastgroup:",m.lastgroup

print "m.group(1,2):",m.group(1,2)
print "m.groups():",m.groups()
print "m.groupdict():",m.groupdict()
print "m.start(2):",m.start(2)
print "m.end(2):",m.end(2)
print "m.span(2):",m.span(2)
print r"m.expand(r'\2 \1 \3'):",m.expand(r'\2 \1\3')

p = re.compile(r'(\w+) (\w+)(?P<sign>.*)', re.DOTALL)

print "p.pattern:", p.pattern
print "p.flags:", p.flags
print "p.groups:", p.groups
print "p.groupindex:", p.groupindex

p2 = re.compile(r'(\w+) (\w+)')
s2 = 'i say, hello world!'

print p2.sub(r'\2 \1', s2)
print p2.subn(r'\2 \1', s2)

def func(m):
    return m.group(1).title() + ' ' + m.group(2).title()

print p2.sub(func, s2)
print p2.subn(func, s2)

>>> ================================ RESTART ================================
>>>
hello
world
['one', 'two', 'three', 'four', '']
['1', '2', '3', '4']
1 2 3 4
m.string: hello world!!
m.re: <_sre.SRE_Pattern object at 0x00000000029F9A70>
m.pos: 0
m.endpos: 13
m.lastindex: 3
m.lastgroup: sign
m.group(1,2): ('hello', 'world')
m.groups(): ('hello', 'world', '!!')
m.groupdict(): {'sign': '!!'}
m.start(2): 6
m.end(2): 11
m.span(2): (6, 11)
m.expand(r'\2 \1 \3'): world hello!!
p.pattern: (\w+) (\w+)(?P<sign>.*)
p.flags: 16
p.groups: 3
p.groupindex: {'sign': 3}
say i, world hello!
('say i, world hello!', 2)
I Say, Hello World!
('I Say, Hello World!', 2)
>>>