how to right the regular expression ?
MRAB
python at mrabarnett.plus.com
Thu Feb 14 10:43:42 EST 2013
On 2013-02-14 14:13, python wrote:
> my tv.txt is :
> http://202.177.192.119/radio5 香港电台第五台(可于Totem/VLC/MPlayer播放)
> http://202.177.192.119/radio35 香港电台第五台(DAB版,可于Totem/VLC/MPlayer播放)
> http://202.177.192.119/radiopth 香港电台普通话台(可于Totem/VLC/MPlayer播放)
> http://202.177.192.119/radio31 香港电台普通话台(DAB版,可于Totem/VLC/MPlayer播放)
> octoshape:rthk.ch1 香港电台第一台(粤)
> octoshape:rthk.ch2 香港电台第二台(粤)
> octoshape:rthk.ch6 香港电台普通话台
> octoshape:rthk.ch3 香港电台第三台(英)
>
> what i want to get the result is
> 1group is http://202.177.192.119/radio5 2group is 香港电台第五台 3group is (可于Totem/VLC/MPlayer播放)
> 1group is http://202.177.192.119/radio35 2group is 香港电台第五台 3group is (DAB版,可于Totem/VLC/MPlayer播放)
> 1group is http://202.177.192.119/radiopth 2group is 香港电台普通话台 3group is (可于Totem/VLC/MPlayer播放)
> 1group is http://202.177.192.119/radio31 2group is 香港电台普通话台 3group is (DAB版,可于Totem/VLC/MPlayer播放)
> 1group is octoshape:rthk.ch1 2group is 香港电台第一台 3group is (粤)
> 1group is octoshape:rthk.ch2 2group is 香港电台第二台 3group is (粤)
> 1group is octoshape:rthk.ch6 2group is 香港电台普通话台 3group is none
> 1group is octoshape:rthk.ch3 2group is 香港电台第三台 3group is (英)
>
> here is my code:
> # -*- coding: utf-8 -*-
> import re
> rfile=open("tv.txt","r")
> pat='([a-z].+?\s)(.+)(\(.+\))'
> for line in rfile.readlines():
> Match=re.match(pat,line)
> print "1group is ",Match.group(1),"2group is
> ",Match.group(2),"3group is ",Match.group(3)
> rfile.close()
>
> the output is :
> 1group is http://202.177.192.119/radio5 2group is 香港电台第五台
> 3group is (可于Totem/VLC/MPlayer播放)
> 1group is http://202.177.192.119/radio35 2group is 香港电台第五台
> 3group is (DAB版,可于Totem/VLC/MPlayer播放)
> 1group is http://202.177.192.119/radiopth 2group is 香港电台普通话台
> 3group is (可于Totem/VLC/MPlayer播放)
> 1group is http://202.177.192.119/radio31 2group is 香港电台普通话台
> 3group is (DAB版,可于Totem/VLC/MPlayer播放)
> 1group is octoshape:rthk.ch1 2group is 香港电台第一台 3group is (粤)
> 1group is octoshape:rthk.ch2 2group is 香港电台第二台 3group is (粤)
> 1group is
> Traceback (most recent call last):
> File "tv.py", line 7, in <module>
> print "1group is ",Match.group(1),"2group is ",Match.group(2),"3group is ",Match.group(3)
> AttributeError: 'NoneType' object has no attribute 'group'
>
> how to revise my code to get the output?
>
The problem is that the regex makes '(\(.+\))' mandatory, but example 7
doesn't match it.
You can make it optional by wrapping it in a non-capturing group
(?:...), like this:
pat = r'([a-z].+?\s)(.+)(?:(\(.+\)))?'
Also, it's highly recommended that you use raw string literals
(r'...') when writing regex patterns and replacements.
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