Hi trying to separate each of the expressions from the colon. So want to obtain 'ss_vv', 'kk' and 'pp'. But the two print expressions below give me 'v' and 'k', so getting parts only of each string. Can anyone see what wrong here?
m0 = re.compile(r'([a-z]|_)+:([a-z]|_)+:([a-z]|_)+')
m1 = m0.search('ss_vv:kk:pp')
print m1.group(1)
print m1.group(2)
In [52]: m0 = re.compile(r'([a-z|_]+):([a-z|_]+):([a-z|_]+)')
In [53]: m1 = m0.search('ss_vv:kk:pp')
In [54]: print m1.group(1)
ss_vv
In [55]: print m1.group(2)
kk
In [56]: print m1.group(3)
pp
What my regex does:
([a-z|_]+):([a-z|_]+):([a-z|_]+)
What your regex does:
([a-z]|_)+:([a-z]|_)+:([a-z]|_)+
No need to use regex for your case. You can just split on basis of ':' and get required output..
>>> a = 'ss_vv:kk:pp'
>>> b_list = a.split(':')
>>> b_list
['ss_vv', 'kk', 'pp']
>>>
What are the other rules for the regular expression? based on your question, this regex would do:
m0 = re.compile(r'(.*):(.*):(.*)')
m1 = m0.search('ss_vv:kk:pp')
print m1.group(1)
print m1.group(2)
UPDATE: as mentioned by @Jan in the comments, for efficient and better use of regex, you can modify it as
regex = r'([^:]+):([^:]+):([^:]+)'
m0 = re.compile(regex)
output:
ss_vv
kk
or by just splitting the string:
string = 'ss_vv:kk:pp'
parts = string.split(':')
print parts
outputs: ['ss_vv', 'kk', 'pp']
[^:]*:[^:]*:[^:\n]* and (.*):(.*):(.*) - do you see the significant reduction in steps? The former needs 36, while the latter needs 284 (9 times!). My point is: the dot-star (.*) brings you down the line and then* backtracks* - which can be very ineffective sometimes. As a general rule of thumb I would say, try to be more specific and try to come to an end faster with regular expressions. Nevertheless, +1 for the splitting option here :)
:?